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Blind-Assist Labeling Template

Team 3 - A Better Way

Kevin Hackett Darren Quelette

Ryan Risdon Steven Rogers

Dominic Rosselli Robert Sampson Joseph Schultheis

Wednesday, June 10th, 2009 Abstract This report covers the design process of a template used to aid in positioning and placing labels on mail for a bulk mailing operation. The objective is to make this template easily adjustable so that a blind mailroom employee can label different kinds of mail efficiently. By using this template the mailroom employee, would become more proficient at setting up the workspace and thus become more productive.   

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Table of Contents

1. Introduction 3

2. Customer Needs Assessment and Revised Needs Statement 4

3. Benchmarking, Standards, and Target Specifications 8

4. Concept Generation 15

5. Concept Screening and Evaluation 35

6.  Final Design Concept 40

7. Prototype Design, Development and Testing 42

8. Design Refinement for Production 50

9. Final Design for Production 55

10. Conclusions 64

References 71 Appendices 72

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1. Introduction 1.1 SW Resources

The company was founded in 1964 by the Association of Retarded Children and the Junior League of Parkersburg, West Virginia. There are five divisions of SW Resources which include: SW Graphics, Mail Plus, Cardability, SW Industries, and Blennerhassett Rehabilitation Center. The company’s mission statement is “to provide vocational services, employment and other opportunities for individuals who have disabilities enabling them to achieve their full potential” (SW Resources, 2008).

The Mail Plus division provides billing, mailing, and direct imprinting services. They specialize in first class and bulk presort services, inserting and folding, bar coding, collating, dot tabbing, data entry, bulk packaging, mail merge, and binding. They currently process over one million pieces of mail annually (SW Resources, 2008). 1.2 Disabilities A person who is disabled is defined by the Americans with Disabilities Act (ADA) as “…a person who has a physical or mental impairment that substantially limits one or more major life activities, a person who has a history or record of such an impairment, or a person who is perceived by others as having such an impairment” (ADA, 2002). Blindness is a common disability which afflicts 1.3 million people in the United States (CDC, 1994). Approximately 35-40% of this population is of working age (18-69) (CDC, 1994), which equates to 455,000 - 520,000 people. Because of their disability, this blind working age population is significantly underemployed, with only 40-45% of the population employed (CDC, 1994). This amounts to 250,000 – 312,000 blind persons of working age who are unemployed in the United States. Bob is a blind person who works in the Mail Plus division of SW Resources. He labels catalogs, magazines, and other bulk mailings, and he uses a special template to aid him in positioning and placing labels. This template functions somewhat effectively, but he uses a series of cardboard cutouts that he must position correctly on the template to label different sizes of mail in the correct position. 1.3 Project 1.3.1 Current Template The current template is made by taking a flat, square piece of wood and fixing two thin pieces to the edges. The pieces are positioned so that they meet at a right angle on the bottom left corner of the wood square. A specifically sized piece of cardboard is then attached with tape to the bottom of the template. When Bob needs to label a different item, such as when moving from a

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magazine-sized to a letter-sized piece of mail, he uses a different piece of cardboard to adjust the size. 1.3.2 Current Standards Though there are no explicit standards for machinery used by the blind, there are rules governing the working environment of the generalized handicapped person. These are specifically outlined in the Americans with Disabilities Act of 1990 (ADA, 2002). The template that the team would design would be labeled under Assistive Technology. The definition of Assistive Technology is explicitly defined as “…any item, piece of equipment, or product system, whether acquired commercially, modified, or customized, that is used to increase, maintain, or improve functional capabilities of individuals with disabilities.” (Assistive Technology, 2008) 1.4 Needs Statement The purpose of the project is to design a template that will address some of the difficulties Bob has outlined. This means making the template easier to adjust in order to accommodate different types of mail. The design will allow Bob to become more productive and enable other blind workers to label mail more easily. 2. Customer Needs Assessment and Revised Needs Statement The FOCUS process is used to assess the needs of our customer. FOCUS is an acronym for Frame the Project, Organized Resources, Collect Data, Understand the Voices, Select Action. By using this iterative process the customer is fully integrated with the decision process. Within SW Resources, several customer points of view were identified. Our contact via email and phone for the project is the communications customer voice. With this individual we discussed when to set up meetings, interviews, and observations of the other employees. Managerial employees at SW Resources were identified as a source of information about the abilities of the workers and the availability and priorities of various potential projects. The employees involved in the potential projects are the third voice of the customer. The employees are asked: What can be done to help you and what ideas do you have for improvement? The employees are also the object of observation as they perform their current operation. The final voice of the customer is any maintenance, janitorial, and stock room employees that would be involved in the potential project. These people are asked: How can our design make maintenance and repairs easy for you? What parts, hardware, and tools should we use that you have in stock or have access to? By utilizing all employees that may be involved in the project at some time, a larger perspective and diverse set of needs and specifications are achieved. The interview and observation guide used to identify the customer’s needs is given below. Interview and observation guide:

1) With managers, create list of areas to observe 2) Observe the entire process, noting excessive movements/steps/hesitations.

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3) Observe problem areas in which: a) A workers’ handicap affects their performance b) The current process is ineffective

4) As a team, select project, and go back to make in-depth observations and interviews with workers.

In enacting this guide, three items were deemed necessary in order to get accurate and useful information. First, conduct interviews in small groups of two or three. Second, conduct observations with permission. Third, take notes, pictures, and videos to record observations. Fourth, compile information, do time studies, and identify problem areas. These steps are repeated in iteration until the customer’s needs are completely identified. Based on this interaction, a set of needs was identified in order to execute a fully successful project. The list of needs represents the customers and teams goals that are to be used to produce a revised, mutually agreeable needs statement. Figure 2.0.1 shows the needs that are to be addressed.

 #    Need           1  The jig  is durable         2  The jig  is lightweight         3  The jig is adjustable         4  The jig will fit a variety of template shapes   5  The jig is ergonomic         6  The jig poses no danger to the user      7  The jig has easily replaceable components   8  The jig will last a long time       9  The jig is easily maintained        10  The jig is inexpensive         

Figure 2.0.1: Customer Needs and Team Goals

2.1 Evaluation / Weighting of Customer Needs

To fully assess the success of each design concept, a set of criteria must be applied to each design, and those criteria in turn must be effectively weighted. Because each evaluation criterion varies in importance for the final design, the weighting will provide differentiation between them. For concept assessment, more important criteria will be weighted more heavily, and less important criteria will have less weight. This is necessary to ensure that the most important criteria will influence decision-making more than less significant items. From the original list of needs, the needs were divided into groups that generalized the need that they were assessing. Figure 2.1.1 below shows how this division occurred.

1. Usable   1.1 The jig is safe   1.2 The jig is lightweight   1.3 The jig is ergonomic 

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2. Durable   2.1 The jig has high durability   2.2 The jig will last a long time   2.3 The jig is easily maintained  3. Adjustable   3.1 The jig is adjustable in quarter inch increments   3.2 The jig will fit a variety of template shapes 4. Customer Maintenance   4.1 The jig is inexpensive   4.2 The jig has easily replaceable components  

Figure 2.1.1: Division of Needs

Based on conversations with the customer and the group’s general engineering knowledge, these needs were weighted as shown in the following table in Figure 2.1.2.

Usable Adjustable Durable Customer Maintenance Total Weighting

Usable 1.00 0.50 2.00 3.00 6.50 0.30 Adjustable 2.00 1.00 3.00 2.00 8.00 0.37 Durable 0.50 0.33 1.00 3.00 4.83 0.22 Customer Maintenance 0.33 0.50 0.33 1.00 2.17 0.10

Figure 2.1.2: Needs Weighting

The revised needs table accounting for these weightings is shown in Figure 2.1.3:  1. Usable (0.30)   1.1 The jig is safe   1.2 The jig is lightweight   1.3 The jig is ergonomic 2. Durable (0.22)   2.1 The jig has high durability   2.2 The jig will last a long time   2.3 The jig is easily maintained  3. Adjustable (0.37)   3.1 The jig is adjustable in quarter inch increments   3.2 The jig will fit a variety of template shapes 4. Customer Maintenance (0.10)   4.1 The jig is cheap   4.2 The jig has easily replaceable components  

Figure 2.1.3: Revised Needs Division

This further assessment allowed the team to apply a rating to each individual need. This rating between 1 and 5 was used in our concept analysis and feasibility meeting to differentiate the design criteria. Figure 2.1.4 shows the results of this differentiation. The rating is known as an

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importance factor for each of the needs. A rating of 5 indicates that the need is very high in importance, and a rating of 1 indicates that the need listed is not important to the project.

 #    Need          Imp 1  The jig  is durable        4 2  The jig  is lightweight        3 3  The jig is adjustable        5 4  The jig will fit a variety of template shapes  4 5  The jig is ergonomic        3 6  The jig poses no danger to the user     3 7  The jig has easily replaceable components  2 8  The jig will last a long time      3 9  The jig is easily maintained       4 10  The jig is cheap          2  

Figure 2.1.4: Importance Factors of Needs

2.2 Revised Needs Statement There is a need to create a more efficient workspace for a blind mailroom employee by creating a device that improves setup over the current process and provides adjustable labeling and packaging.

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3. Benchmarking, Standards, and Target Specifications 3.1 Benchmarking 3.1.1 Label Peeler A non-electric label peeler is modeled off of the design by Weber, in which the user pulls the paper that the labels are on over a sharp edge. Because of the abrupt change in direction of the paper, the label is peeled off. The current design incorporates an electronic push button that advances the paper a specified distance. The Weber design is shown below in Figure 3.1.1.1.

Figure 3.1.1.1: Weber label peeler (Originals by Weber, 2008) There are other label peelers that are in use that range from complex to simple. One of the simpler ways to peel the label is to use a hand held plastic device as shown below in Figure 3.1.1.2:

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Figure 3.1.1.2: Label peeler from Garvey (Garvey, 2008)

However, the problem with this solution is that the customer is blind and it would be troublesome for him to keep track of a small plastic peeler. Other more advanced peelers are in production like one made by Avery, shown in Figure 3.1.1.3:

Figure 3.1.1.3: Avery label peeler (Avery, 2008)

Unfortunately, this model is roughly $200, and it only works with Avery label products. Also, since the there are moving parts, there is a greater chance that injury could occur. These cost and safety issues affect the usefulness of this product to the design.

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There are several automatic label peelers combined with a label applicator. These usually employ tamping or compressed gas to remove the label and apply it firmly to the object (Allen, 1997). One that incorporates some of these features is shown below in Figure 3.1.1.4:

Figure 3.1.1.4 Allen labeling machine (Allen, 1997) The problem with this kind of machine is that it is complicated and is probably out of the team’s capabilities to produce. Also if it did not replace Bob’s job, it would not be as safe to use as his current jig. From the picture it is obvious that there are many pinch points and safety hazards especially for a blind employee. 3.1.2 Rubber Band Applicator The rubber band applicator works by providing a location for the magazines to placed in order to ease the placement of a rubber band around a complete stack of labeled mail. The rubber bands are stored on the curved section of the applicator shown below in Figure 3.1.2.1. When the user

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has the desired amount of mail in the holder, the user moves a rubber band from the holding area to the pile of mail.

Figure 3.1.2.1: Rubber band applicator

Similar designs are in production. These include one from Assistive Technology solutions as shown below in Figure 3.1.2.2:

Figure 3.1.2.2: Assistive Technology Rubber Band Applicator (2008)

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The applicator is currently designed to apply rubber bands to legal size documents but can be modified to accommodate other sizes. 3.2 Standards The method for determining the possible applicable standards included examining the entire labeling process that Bob needs to go through in order to label the mail. Next we determined the appropriate equipment that was needed to label the mail. From this, we determined our search criteria for possibly applicable standards. The main search criteria were standards for machinery in use by blind employees. More specifically we were looking for any information about pinch points, sharpness of edges, materials, etc. After searching through major legislation like the Americans with Disabilities Act of 1994 and the Assistive Technology Act of 1998, there were not any specific requirements for the search criteria mentioned above. Most of the information involved building codes and requirements for hiring people with disabilities. However, there were some requirements from the sources that should be taken into consideration when designing the workspace. Section 4.2.5 of the ADA deals with the forward reach requirement for people in wheel chairs and states:

“If the clear floor space only allows forward approach to an object, the maximum high forward reach allowed shall be 48 in (1220 mm) (see Fig. 5(a)). The minimum low forward reach is 15 in (380 mm). If the high forward reach is over an obstruction, reach and clearances shall be as shown in Fig. 5(b).”

(See Figure 3.2.1) The reason this applies is that since Bob is a blind employee his work area needs to be as efficient as possible so that he does not lose any items he might need for his labeling job. This means that any item that the team designs would need to meet these requirements and must lie within hand reach. After extensive benchmarking and searching with the aid of an engineering librarian, no applicable standards were found in relation to blind usage of a labeling template. Standards will apply for the project however. There are applicable ASME standards related to various aspects of the project. Foreseeable applicable ASME standards include standards for GD&T, engineering drawings, metal products, screw threads, surface quality, limits and fits, fasteners and possibly others. The application of these standards will be applied when it comes time for their related activities. The lack of a complete concept design however prevents the team from specifically applying these standards.

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Figure 3.2.1: ADA Figure 5 – Maximum Forward Reach over an Obstruction (ADA, 2002)

3.3 Target Specifications, Constraints, and Design Criteria

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3.3.1 Target Specifications The specifications for the jig need to meet certain criteria. These target specifications are a combination of specifications requested by the customer and team determined requirements. After meeting with the customer and discussing a list of criteria that the jig must accomplish, a list of target specifications was complied. The complete list of target specifications can be seen in Figure 3.3.1.

Jig  Value  Units Size  <16  Inches Stop Strip Dimensions  1 x ¼  Inches Adjustability (up and down)  0 – 4  Inches Adjustability (left and right)  16  Inches Increments  (up, down, left, and right) 

¼ Inches 

Corner Stop  90  Degrees Drop Height Durability  4  Feet Expected Lifetime  5 – 10  Years Affordability  < $200  USD Weight  < 10  Pounds Corrosion Resistance  Close materials  Galvanic Scale Template Deflection  ¼  Inches 

Figure 3.3.1: Target Specifications 3.3.2 Constraints The jig and any additional “delighter” features must be able to fit onto the table that the customer currently works on. A drastic increase in the space needed for the label application process can limit the productivity of the customer. Increasing the workspace can also limit the workers in his immediate work area. 3.3.3 Design Criteria Some of the target specifications that were added to the list of customer requested specifications include expected lifetime. The customer made no remarks about an expected lifetime of the jig, but this was a specification that needed addressed. The affordability of the device was also not specified by the customer, as that was a team-based decision that was determined by available budget. The weight of the jig was also not specified by the customer but included as a target specification. 4. Concept Generation 4.1 Patent Searching

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The team found few patents for manual label applicators. However, US Patent 4369582 (Pfeffer, 1983) presented a possible way to provide adjustability for the template. The following graphics show the way in which this label applying template accomplished adjustability. Figure 4.1.1 shows how the piece slides across the template. Figure 4.1.2 shows how the piece is secured once the desired position is accomplished. Because adjustability is a top priority for the concept, this idea could be applied to accomplish this need. Not included in this adjustability idea is the ability for a user to be aware of the features position without the use of sight.

Figure 4.1.1: Thumb screw isometric view (Pfeffer, 1983)

Figure 4.1.2: Thumb screw side view. (Pfeffer, 1983)

US Patent 4626313 (Karp, 1986) was another concept that was researched. This device creates a method to peel labels from a sheet of labels. This concept can be used to ease the removal of the labels from the sheet. Figure 4.1.3 shows the roller used to remove the labels from the sheet.

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Figure 4.1.3: Front view of label roller. (Karp, 1986) Figure 4.1.4 shows the whole device.

Figure 4.1.4: Complete device side view. (Karp, 1986)

A close up view of the actual label removing design is shown in Figure 4.1.5.

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Figure 4.1.5: Label removing device side view. (Karp, 1986)

US Patent 4660885 (Suhr, 1987) is a locking mechanism that is being considered by the team for fixing the template location. This component is designed to lock a seatback into various positions using a stepwise locking mechanism. With spring force and a locking lever, the seatback can be positioned at various heights according the separation of teeth on the guide bar. This motion can be done with one hand due to the lever being pivotally mounted. The design would help in positioning the labeling template and locking it quickly.

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Figure 4.1.6: Isometric view of lever and guide in spring loaded compression. (Suhr, 1987)

US Patent 4221430 is a “low cost, highly convenient, and non-complicated push button adjuster (Frobose, 1980).” A spring loaded push button is used to shift a connected locking pin out of a detent slot in the support bar. The adjustable part is free to move until the button is released and relocked into a different position. A locking mechanism such as this would be extremely beneficial to the team’s design. It would be easy to create and simple to use. Eliminating the use of a thumb screw will decrease setup time and the amount of wear the mechanism will undergo.

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Figures 4.1.7 and 4.1.8: Side and Back view. (Frobose, 1980)

A different approach to the labeling process involved an automatic feed of the pieces of mail to reduce the motion of the customer to take each individual piece of mail and insert it into the labeling template. This idea was based off of the Adjustable Self-Leveling Plate Dispenser (House, 1976), US Patent 3937361. This design, shown below in Figures 4.1.9 and 4.1.10, could be modified to allow mail to be stacked inside of a housing, and as each piece is removed the whole stack would rise to the top until every piece has been labeled.

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Figure 4.1.9: Outside Isometric and Top Views of Patent 3937361 (House, 1976)

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Figure 4.1.10: Cross-Sectional Side Views of Patent 3937361 (House, 1976)

4.2 Concept Generation In generating possible concepts, the group held a meeting to have a brainstorming session. There were no notes; it was a very informal meeting. Members spoke at will to generate individual ideas in response to the problem and target specs at hand. The purpose of this meeting was simply to get the creative ball rolling, and so afterwards there was a cluster of different small ideas in the group. The next step was about a week later when another meeting was held. The group met in the design room in Stocker so ideas and concepts could be written on the dry erase boards. Each member was instructed to come to the meeting prepared with one or two concepts which were developed by the group of ideas already presented in the first meeting, as well as using new breakthroughs and thoughts found individually in the previous week.

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At the meeting, each member drew their concept sketch on one of the dry erase boards. Once all the concepts were up, each design was given a number, and one by one the creating group member described in detail the parts, problems, and operation of their concept. The next step included feedback, advice, and more brainstorming from the entire team directed at each concept. Once the new ideas were applied, and simplifications were considered and implemented, the group looked to combine any concepts that had similar ideas and functions, but that had their own flaws which could be solved by an idea applied in another concept. The main functions that needed to be provided in all concepts can be categorized into a means of securing and a means of adjusting incrementally. Figure 4.2.0 below briefly shows the means for each function that were considered. There are many more ideas for adjustability than security because of its much larger impact on the overall design of the labeling jig.

Function Means Adjustability Security

1 Rack and Pinion Thumb Screws

2 Grooves with Roller Wing nuts

3 Screw Feature (Y-direction only) Peg Hole

4 T-slot or similar Rail Sliders

5 Graduated Spiral Notebook (Y-Direction only)

6 Pegs and Peg Holes

7 Threaded Rod

8 Crank Figure 4.2.0: Morphological Chart

4.2.1: Concept 1 The first conceptual design developed is shown in Figure 4.2.1.1 below. It consists of an 18” by 12” flat backing to which two stainless steel bars are attached on the left and bottom to form a 90° angle in the bottom left corner of the workspace for the customer to use as a square point of reference. Stainless steel was chosen as the material because it will be handled often and needs to be corrosion resistant. The bottom bar has evenly spaced grooves ¼” apart from trough to trough for a roller on the vertical bar to set the horizontal position of the jig. A cutaway side view of these grooves is shown in the sketch. The depth of each groove would have to be calculated to support ease of movement and rigidity for use. The roller is attached by a spring to the vertical bar and will click each time it lowers into the groove. Below the grooved bottom bar is a second bar with a T-slot to support the rigidity of the vertical bar when it is being pressed down by the user. The vertical bar supports a horizontal bar in a similar way with grooves and a roller attached to the horizontal bar. There is also a T-slot in the side of the vertical bar to support

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rigidity of the horizontal bar. It is located on the side to increase the workspace size. A cutaway side view of the vertical bar is also shown in the sketch. There is a ¼” clearance between this bar and the backing, and the horizontal bar and the backing to allow space to slide mail under the bars. The horizontal bar attached to the vertical bar supports the plastic template used to locate the labeling position on each parcel that is squared in the bottom left corner. Plastic was chosen as a material because it is flexible and will bend down to the backing elastically. It is connected to the horizontal bar with four standard screws.

Figure 4.2.1.1: Conceptual Design #1

This design meets all of the customer requirements: (1) it is square, durable and has raised edges, (2) it has a slide able and extendable position marker that can be locked in place, and (3) the position marker can be placed in many positions to account for different mail sizes. All of the bars are stainless steel, so they meet the strength requirement. The design is such that sufficient rigidity will accompany the setup. It is very flexible in locating a position anywhere on the workspace. One important advantage of this design is that there is a passive locking system with the grooves that will maintain the set position without additional steps to lock it down, and this will save time for the operator. 4.2.2: Concept 2 Concept 2 involved a gear train to adjust the labeling template on a similar backing to Concept 1. This concept never really got off of the ground; however, it was accompanied by two ideas for “delighter” features that will be covered in Section 4.2.11.

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4.2.3: Concept 3 This concept is based upon a square board made of a sturdy and durable material that measures 16 inches by 16 inches. There will be a 1 inch wide raised area around the bottom and left side of the device. This will leave a recessed area that will be 15 inches by 15 inches to allow the mail or catalog to be lower than the securing device. This can be seen in Figure 4.2.3.1.

Figure 4.2.3.1: Top view of Concept 3

There will be a plate that will rest on the 1 inch raised strip that can be locked in place with thumbscrews or wing nuts. This locking plate can be seen with better detail in Figure 4.2.3.2.

Figure 4.2.3.2: Side view of Concept 3

The remaining dimensions of the device have yet to be determined based on material selection and ease of manufacturing. The template device used to position labels will resemble a “spiral notebook.” It will have several “sheets” each varying in length from 1 inch to 4 inches in increments of ¼ inch. This can be seen in Figure 4.2.3.3.

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Figure 4.2.3.3: Spiral notebook template concept

The spiral notebook template system will be held in place by the locking plate on the labeling device. The desired length can be selected and placed into the device and then locked down. The remaining unused template lengths will hang off the bottom of the device out of the way of the user. The templates will be made of a thin and flexible plastic that is durable to allow for a long lifetime. This concept was chosen as a feasible candidate for prototyping. 4.2.4: Concept 4 This concept is also based upon a square board made of a sturdy and durable material that measures 16 inches by 16 inches. There will be a 1.45 inch wide raised area around the bottom and left side of the device. This raised area will provide a perfectly square corner in which to put the mail or catalogue. The raised area will have 0.40 diameter holes spaced ½ inch apart. This can be seen in Figure 4.2.4.1.

Figure 4.2.4.1: Top view of Concept 4

The holes will be recessed to a depth of 1 inch to allow the template holder to be positioned along the raised area. This can be seen in Figure 4.2.4.2.

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Figure 4.2.4.2: Side view of Concept 4

The template device used to position labels will resemble a “spiral notebook.” It will have several “sheets” each varying in length from 1 inch to 4 inches in increments of ¼ inch. This can be seen in Figure 4.2.4.3.

Figure 4.2.4.3: Spiral notebook template concept

The spiral notebook template system will be held in place by the locking plate on the template holder. The desired length can be selected and placed into the holder and then locked down. The remaining unused template lengths will hang off the bottom of the holder out of the way of the user. The templates will be made of a thin and flexible plastic that is durable enough to allow for a long lifetime. The template holder will be made out of a similar material as the rest of the device. It will be 5.9 inches long and 1 inch wide. There will be a movable top plate that can be adjusted to lock the template in place. This can be seen in Figure 4.2.4.4.

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Figure 4.2.4.4: Top view of template holder

The adjustable plate will be held in place with thumb screws or wing nuts. The pegs will be slightly less than the 0.4 inch diameter to fit into the recessed holes of the jig. Only the top portion of the peg will be threaded to allow the plate to be locked into place. This can be seen in Figure 4.2.4.5.

Figure 4.2.4.5: Side view of template holder

The template holder will fit into the recessed holes on the jig and can be adjusted left or right to position the template at any desired location. Figure 4.2.4.6 shows the entire assembly of the device.

Figure 4.2.4.6: Top view of complete device for Concept 4

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4.2.5: Concept 5 This concept is based around four rails and three linear bearings. The device is easily adjustable to cover a very large area that goes well beyond the technical specification. All rail notches are one fourth of an inch apart, allowing the user to know the location of the template by touch and by sound. The notches act as guides for the two cranks which will move the linear bearings a fourth of an inch a time. The template will need to start at any of the four corners prior to counting in order to ensure the correct distance is acquired. An important aspect of this concept is the fact that there will be no features interfering with the labeling process above the template. This will allow for the user to position the label just as he has been. One disadvantage of this idea is that the customer will have to slide the mail-piece under the rails when placing it against the bottom left corner. A schematic of this design is in Figure 4.2.5.1.

Figure 4.2.5.1: Concept 5

4.2.6: Concept 6 Concept 6 is based around two rack and pinion systems. The coverable area is just enough to satisfy the technical specification. Each pinion will have a knob which the user can turn to find the correct position. The pinion will be free sliding when the arms are unlocked. A click system will be in place to tell the user every time a fourth inch increment is reached. Once the correct dimension is met, a quick push button locking mechanism will be applied to secure the template. There will be one on each axis. In order to insure safety around the gear joints there will be finger guards installed around all pinch points. A schematic of this concept is in Figure 4.2.6.1.

Figure 4.2.6.1: Concept 6

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4.2.7: Concept 7 Concept 7 uses two rack and pinion assemblies for the X-directional movement of the label placement holder, as shown in Figure 4.2.7.2, and a screw feature for the Y-directional movement, as shown in Figures 4.2.7.1 and 4.2.7.3. The following graphics show some of the detail.

Figure 4.2.7.1: Concept 7 Top View

Figure 4.2.7.2: Concept 7 Bottom Side View

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Figure 4.2.7.3: Detail for Label Placement Holder

The concept of this jig is to have the label placement holder sandwiched between two rack and pinion configurations. The center fixture would be marked by rack gearing on both the top and bottom and enough thickness to allow for the label placement fixture to move in the Y direction from within it. Both of the pinions are fixed in position. Figure 4.2.7.2 shows how as the label placement holder is moved away from the middle. The result is that center fixture, which is shown in the figure as a long horizontal white bar, can move up to 6 inches beyond the original 16” template. The group could attach a rotating knob to one of the pinions that would allow the user to move the center piece by adjusting one of the knobs. There a couple ways to accomplish measurement without using a ruler to find where the label placement holder is located. The first is by running the knob though gear pairs that make some distance the result of a certain amount of rotation, for example a one inch distance is achieved through one full 360° turn. Another option would be to create some sort of mechanism that makes a noise per every ¼” of measurement. The disadvantage of both of these options is that the user must rely on holding places in his head. However, the user has high mental capacity and since the largest deviation from the zero position would be six inches, it is likely that there would be little trouble with this design. Accomplishment of the Y directional movement of the label placement holder is shown in Figure 4.2.7.3. This mechanism must be offset in the negative Y direction so that the user can bring the label placement holder all the way to only ¼” from the bottom strip. A screw is used for the adjustability. The screw is fixed to a stationary piece attached to the top of the bottom strip configuration. It is attached the actual label placement holder by bolts and an unthreaded hole so that the only translated motion is in the Y direction and the label placement holder is not forced to rotate along with the screw. Measured movement of this could also be accomplished by the attachment of a gear box. The gearing would likely be lower in this case.

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There are some significant disadvantages to this system. It may be difficult to create a small enough mechanism to accomplish the design shown in Figure 4.2.7.3 without sacrificing integrity. Furthermore small pieces may fail more often and be harder to maintain. Also, the motion of the middle piece up to 6 inches beyond the original jig may provide a safety or space concern. Also, if the group cannot create a feasible way for the user to locate measurements using the adjustability features then this design will have failed. 4.2.8: Concept 8 Concept 8 is a simple and versatile concept that aims to achieve, and in some cases exceed, the customer requirements. This concept uses a peg and hole system to adjust the labeling template in the horizontal direction. The peg holes are incremented by ¼’’ along the entire length of the top and bottom of the base template. There is no tightening required to secure the movement in this direction. While the pegs are in the holes, it will be secure until the pegs are pulled back out of the holes. A main problem aimed to be solved is the ability for Bob to set up his device independently. In this device, all he needs to be told is where to place the label in the horizontal direction. From there, as long as he starts at the far left or far right extreme, he can feel each ¼’’ increment as the pegs slide over and past them, so he always know where he is on the template. The base template, made of a material not yet determined, is angled at 90° along two of the edges to allow for the paper object to be perfectly square to the rest of the template. The base dimensions are 16’’x 16’’.

Figure 4.2.8.1: Concept 8

For adjusting in the vertical direction, the plastic bendable piece (which is indicated with the horizontal lines in Figure 4.2.8.1) is suspended between two T-slot rails. Using a wing nut or other hand fastener, the plastic piece can be secured or loosened to adjust anywhere along the T-slot rail. This concept allows for labeling across the entire 16’’x 16’’ template, which exceeds the 16’’ x 4’’ customer requirement. A possible problem with the design concept that may need to be addressed is the ease of use when applying the labels. As shown above, the labels are applied directly above the plastic piece after Bob bends the piece to the base plate. The issue may come up that Bob cannot always get the labels placed between the two sliding rails, which may be an obstruction.

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4.2.9: Concept 9 A schematic of conceptual design 9 is given below in Figure 4.2.9.1. The vertical and horizontal adjustment are actuated by Acme threaded rods and nuts. Knobs are placed at the ends of the rods to allow the user to rotate the rods, and cause a linear force in the nuts. Hardened and ground shafts are placed in parallel with the threaded rods. These guide shafts provide the anti-rotation required for the Acme system to provide linear motion. Linear bearings are used to guide the template assembly on the shafts. The rods and shafts are placed very close together so that moment forces and misalignments do not jam the sliding motion along the shafts. The labels are easily placed with an unobstructed template area in this design. Also, the letter or magazine to be labeled is unrestricted on the top and right to allow easy insertion and removal of the work.

Figure 4.2.7.1: Concept 9

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4.2.10: Concept 10

 Figure 4.2.10.1: Concept 10

This design is based off of a plate dispenser that is used in restaurants to hold a stack of plates and automatically raise up the next plate after one is removed, US Patent 3937361 (House, 1976). A stack of mail to be labeled is placed inside of the apparatus on top a plate. The plate is supported by a spring between it and the bottom of the apparatus. The top of the rectangular system has the combined conceptual design for the labeling template. The idea behind this design is that the customer could place a large stack of mail into the machine and label the top piece, then pull out the top piece and the next would automatically rise to the top. This would eliminate the motion of picking up an individual piece of mail and inserting it into the labeling template, thus reducing the time it takes to label a single piece of mail and increasing the customer’s productivity. The problem with this design is that it would need to be adjustable for different sizes of mail. This could be problematic, because the design would have to be for the largest size mail that is to be labeled, and the stack would have to be able to be stabilized all the way down to the smallest sized mail. There would also have to be plates that go down inside of the apparatus to stabilize smaller pieces. In addition, these stabilizers would also have to permit the bottom plate to rise as mail is taken off of the top. The patent for the plate dispenser accounts for different sizes with adjustable stabilization bars that are outside of the self-rising center. Another challenge would be to find the correct spring force for the plate. In addition, this design would have to be placed on the floor and this could impede the workspace of other employees in Mail Plus.

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4.2.11: “Delighter” Features In addition to the customer requirements that are shaping our project and concepts, the group hopes to add some additional assistance to the performance of Bob’s job. While labeling, Bob piles up whatever mailer is being labeled beside him. Once a pile of a certain size is made, Bob has to apply rubber bands to the pile and place it in a bag. In observations, the rubber banding was an awkward and cumbersome task for him to accomplish quickly. A rubber band applicator concept was devised to ease his rubber banding task. The rubber band applicator works by providing a place for the magazines or other work piece to be placed and allowing ease of placing the rubber band. The rubber bands are stored on the curved section of the applicator shown below in Figure 4.2.11.1. When the user has the desired amount of mail in the holder, the user moves a rubber band from the holding area to the pile of mail. This concept, since not specified as a requirement from the customer, aims to increase the speed of this process as an extra perk in the group’s assistance of Bob. In developing this concept further, possible safety issues must be explored to determine the likelihood of painful rubber band snaps.

Figure 4.2.11.1: Rubber band applicator

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5. Concept Screening and Evaluation 5.1 Concept Screening The concept screening processes involved a combination of individual work, group discussion and customer feedback. Before any concept development occurred the group went to the customer to assess his needs. Through our initial conversation with him, the group developed an idea of what would need to be addressed. The group also took notes detailing the layout that the customer specified. Although this would not preclude radical design changes, the customer specified dimensions that would be required if the group pursued the idea of making a similar but improved jig. Using the information provided by the customer, the group set forth to develop and select a concept. The processes started with individual brainstorming in which each member of the group was assigned to come up with various ideas to solve the problem. Initially each member was tasked with creating three unique designs from which the group would develop one final concept. Each group member was provided the specifications required by the customer and each group member was aware of the needs the customer had and the challenges he faced. Following the initial concept generation by each individual the group met as a whole to give informal feedback to each design. This process involved presenting the idea to the group, detailing its features and explaining how it would respond to customer needs. The group would then assess the strengths and weaknesses of each design and in turn make suggestions for improvement. This processes also allowed group members to use the creativity of other concepts to improve their own concepts. The group intended to meet with the customer to gather additional feedback at this time however due to work related issues he could not be reached for feedback.

Following the group brainstorming and critiquing section, each member was then tasked with developing one or two designs that was a more thorough and encompassing answer to the problem. Each group member brought this concept to a formal reviewing session. An explanation of how the formal reviewing session operated is detailed below. At this point the group was hoping to also get feedback on these nine designs from the customer, however through work related issues he could not be reached for feedback. The following graphic, Figure 5.1, depicts the original formal design selection process. Shown in green are the processes that have already been described.   

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 Figure 5.1.1: Initial Concept Selection Process

 The formal review step is shown above in Figure 5.1 in red. The intention of this step in the process was to narrow our focus down to a handful of designs that showed the greatest potential. By doing this, the group could better use resources towards what the group hoped to be a more fruitful model. For the review, rating criteria was applied to each design. Because each group member developed a concept that had at least a basic and feasible answer to each need of the addressed customer needs, a rating system was needed to define which one appeared to have the most potential. To make this decision we used a matrix rating system. Each group member assessed the success of each concept based on six factors: feasibility, ease of use, simplicity, cost, durability and safety. Each team member scored each concept on each category on a scale of 1-5, five being the most favorable. For example a 5 in feasibility means that the concept was very feasible. A 5 in cost indicates that the concept would be cheap.

For the purposes of the project the six categories are important to the project in different ways. Feasibility is intended to be a measure of the projects likelihood of success. A concept that deserved a high rating in this category was simple to produce. A highly complex concept would likely be difficult to create. The ease of use category reflected the group’s perspective on how successful the jig would be a streamlining and simplifying the customer’s process. A jig given high marks in this category would have as few as possible manipulations from the customer during use. Simplicity reflected the overall simplicity of the design. The group favored a simple design because a simple design would have maintenance advantages. Simplicity in this case reflected the customer’s ability to understand and maintain the product so that there would be increased longevity and success. Cost reflected the projected expenses involved in the production of the concept. High cost is unfavorable. Durability reflected the structure of the jig. If group members perceived structural weaknesses associated with certain designs than the

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concept was rated unfavorably in this category. The group intended to design a product that would be sturdy. The last category, safety, was a reflection of how group members perceived the danger of injury to the customer. Although no concept brought a high risk of injury, safety was a concern as there was a chance for sharp edges and pinch points to be dangerous to the customer especially considering his disability. An importance factor was applied to each category that reflected the significance of each category to the overall success of the jig. The importance factor was also on a scale of 1-5. Because the group agreed on the importance of each rating criteria, they were each given whole numbers. The safety and ease of use criteria were both given 5’s. The group believed that these two categories were the most important aspects of our design. If the jig was dangerous to the consumer, the team would have failed to improve the working conditions of the customer. If the jig was hard to use than the group would have also failed. Feasibility, simplicity and durability were all given 4’s. These factors were all important to the success of the jig however they were not as critical as ease of use or safety. The cost factor was given an importance factor of two. The group intended to keep the material costs of the jig under $300. The group did not foresee issues with this based on the concepts and therefore cost was given a fairly low importance factor.

The rating system and the results are reflected below in Table 5.1. The numbers in the matrix reflect the average team score in each category. Each team member gave a rating to each concept for each category and to populate the matrix, the average of each team member rating was placed in the corresponding box.

  

  

Importance

Factor 1 2 3 4 5 6 7 8 9

Feasibility 4 3.4 3.1 4.4 2.9 3.9 4.3 3.7 4.3 3.6 Ease of Use 5 3.3 3.9 3.6 3.7 4.3 3.8 3.7 3.3 3.7 Simplicity 4 3.1 2.6 4.1 2.7 3.3 3.9 3.7 4 3.4

Cost 2 3 2.7 4.1 3.1 2.7 3.9 3 3.7 3.4 Durability 4 3.1 3.4 4 3.6 4 3.9 3.7 3.7 4

Safety 5 4 3.9 4.4 4 4 4.1 3.7 4.4 3.9    Overall Rating 2.81 2.81 3.41 2.83 3.18 3.32 3.03 3.26 3.08

 Table 5.1.1: Rating of 9 Concepts

 The results of our analysis indicated to us that Concepts 3, 5, 6 and 8 were the most attractive options to pursue.

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Through this process three specific designs were chosen which the group wanted to move forward with. Each member was then assigned to take a concept and address each issue associated with it and return with a concept that was complete, feasible, and the most attractive answer to the design issues. Although each group member failed to create an original design following this meeting, the lack of originality helped the group decide that they were in fact pursing the most complete concept. Out of the handful of ideas the group narrowed the basic concept down to what the group thought would be a successful base and x-directional concept. At this point the y-directional concept was still in the air, however the x-directional concept selected provided flexibility for any number of y-directional concepts. The creation of the y-directional concept was the most difficult development for the group. Though the group had multiple concepts none were entirely feasible. Through numerous meetings the group developed a concept that could serve as the y-directional assembly. Based on this idea the group again attempted to meet with the customer. To successfully communicate the current ideas, the group constructed a design mock-up that would aid in the feedback process. The group successfully contacted the customer and brought the design mock-up to him for feedback. The customer updated his specifications and gave recommendations based on the current product. Because all of his feedback resulted in only slight modifications, the group did not do any major redesigning. For example, rather than use a y-directional assembly that was adjustable in measurable ¼” increments, the customer informed us that a fully adjustable, immeasurable y-directional assembly would better serve his needs. 5.2 Feasibility and Effectiveness Analysis The feasibility and effectiveness of our project is ultimately be determined by the customer’s use of the final design. Until then the feasibility and effectiveness is determined by how closely the design concepts match the customer needs and how the design compares to the current operation. The feasibility of the various designs is decided by the criteria listed below in Figure 5.2.1. A solution that cannot meet any one of these criteria is considered not viable. From the table none of the concepts are completely unworkable, but Concepts 1, 2, and 4 are the least feasible. This is also demonstrated in the feasibility ratings given in Section 5.3.

Design 1 2 3 4 5 6 7 8 9 Time ~within schedule Y M Y Y Y Y Y Y Y Tools ~within lab capabilities M Y Y Y Y Y Y Y Y Cost ~within budget M M Y M Y Y Y Y Y Skills ~within team skills Y Y Y Y Y Y Y Y Y Feasible Yes or No M M Y M Y Y Y Y Y

Figure 5.2.1: Feasibility Criteria (Y = yes, N = no, M = maybe)

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5.3 Concept Development, Scoring and Selection Prior to the meeting on 11/9/08, each team member was to sketch at least one conceptual design on his own without collaboration with anyone else on the team. Nine conceptual designs were made by the seven team members, and were presented at the meeting by the team member who thought of each design. Everyone explained what their design was and how it worked to the other team members and they asked any questions that they had about the designs for clarification. After everyone had presented his design, the team wrote down ratings on a scale of 1-5, with 5 being the highest and 1 being the lowest, for each of the designs. Each design was rated on the criteria listed in Figure 5.3.1 below, and each criterion was given an importance factor to give proper weighting to the importance of that rating. The team then shared their ratings and the average rating from the seven members was entered into a spreadsheet for each criterion and design. Figure 5.3.1 also shows the average team rating for each of the designs listed by number.

Team Average Rating Criteria Importance Factor 1 2 3 4 5 6 7 8 9

Feasibility 4 3.4 3.1 4.4 2.9 3.9 4.3 3.7 4.3 3.6Ease of Use 5 3.3 3.9 3.6 3.7 4.3 3.8 3.7 3.3 3.7Simplicity 4 3.1 2.6 4.1 2.7 3.3 3.9 3.7 4 3.4Cost 2 3 2.7 4.1 3.1 2.7 3.9 3 3.7 3.4Durability 4 3.1 3.4 4 3.6 4 3.9 3.7 3.7 4Safety 5 4 3.9 4.4 4 4 4.1 3.7 4.4 3.9

Figure 5.3.1: Ratings and Criteria for Conceptual Design Selection These ratings were then multiplied by the importance factor for each criterion to give an average team score for each criterion and design. The scores are shown in Figure 5.3.2. The averages of the scores for each design across all criteria was then found, and this was divided by the sum of the importance factors so that the weighted rating would appear on the same 1-5 scale as the original ratings and the important factors would be divided out.

Team Score for Concept _ Criteria Importance Factor 1 2 3 4 5 6 7 8 9

Feasibility 4 13.6 12.4 17.6 11.6 15.6 17.2 14.8 17.2 14.4Ease of Use 5 16.5 19.5 18 18.5 21.5 19 18.5 16.5 18.5Simplicity 4 12.4 10.4 16.4 10.8 13.2 15.6 14.8 16 13.6Cost 2 6 5.4 8.2 6.2 5.4 7.8 6 7.4 6.8Durability 4 12.4 13.6 16 14.4 16 15.6 14.8 14.8 16Safety 5 20 19.5 22 20 20 20.5 18.5 22 19.5 Average Score 13.5 13.5 16.4 13.6 15.3 16.0 14.6 15.7 14.8

Total Points

Possible 24

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Overall Rating 2.81 2.81 3.41 2.83 3.18 3.32 3.03 3.26 3.08Table 5.3.2: Conceptual Design Scores and Weighted Average Ratings

The highest rated conceptual designs were 8, 6, 3, and 5. A combination of the concepts from these designs will be the basis of the final conceptual design. The lower rated designs have not been completely ruled out and will be taken into account while conceptualizing the design of the final product. Customer feedback is necessary to reach our final conceptual design decision. We will present to him the conceptual designs that have been described as the most feasible options, along with the alternative design in Concept 10 to see if he is interested in changing the process in a fundamental way. We will use the voice of the customer as a guide to the finalized conceptual design choice.

6. Final Design Concept 6.1 Concept Selection The idea behind the final design is to improve on the following aspects of the current set up in regards to number of steps, ease of steps, and likelihood of error. The design allows the user to set up for labeling in three simple steps. First, the user takes a pre-labeled piece of mail and locates it in the square corner. Keeping his hand on the label, he then adjusts the knob on the right side until the template is in the correct horizontal position. To adjust in the direction away from the user he loosens the thumb screw on the slider, moves the slider, and then retightens the thumb screw when it is in the correct position. At this point the user is ready to place labels on mass mailings by using the thin plastic tab attached to the end of the slider as a position guide. The plastic tab is the same width as the labels, and it flexes down to the working area when it is pressed down by the user. A detailed view of the setup procedure can be seen in Figure 6.6.1.

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Figure 6.1.1: Final Design Rendering & Steps for Setup

6.2 Detailed Design Description The working space in the design is 16 inches wide by 12 inches out from the user in order to accommodate different sizes of mail. The user can adjust in the full range of the horizontal direction and half of the range in the vertical. Only half of the vertical range is needed because the mail can be turned 180° and will never be greater than 12 inches on the shortest side. The horizontal motion is achieved with an Acme-threaded rod and nut system to which is attached the vertical adjustment. The vertical adjustment is a plastic T-shaped slider that is clamped in an aluminum bracket with thumbscrews. The plastic tab is permanently attached to the end of the T-slider using small machine screws. It is the main interface between the user and the mechanism, as he uses its position to locate the exact position of the label on each piece of mail. The user can set its position once and go through an entire lot of mailings of the same size. The rear of the template is elevated with a leg in each of the two corners to provide a more ergonomic workspace that is tilted up towards the user. A rendering of the final prototype can be seen in Figure 6.2.1.1. Photographs of a user operating the jig can be seen in Figures 6.2.1.2 through 6.2.1.4.

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 1. Prototype Rendering 

 2. X‐Direction Adjustment 

 3. Y‐Direction Adjustment 

 4. Securing T‐Slider 

Figure 6.2.1: Rendering and Operational Photographs We chose materials that balanced cost with sturdiness. The working space is made of plastic, and it is reinforced with a welded steel frame backing. The Acme-threaded rod is steel, and the polymeric Acme-threaded nut is encased within the frame, which not only helps provide rigidity but also prevents the user from being pinched by the threads and the traveling nut during adjustment. There are no moving parts while the template is in use, which makes the device very safe.

7.0 Prototype Design, Development and Testing

7.1 Failure Modes and Effects Analysis (FMEA) The team performed an FMEA on the conceptual design to determine what critical-to-quality items needed to be addressed before constructing the final prototype. We designed our analysis using the standard rating system of a risk priority number (RPN) that is the product of three ratings for severity of failure (SEV), likelihood of occurrence (OCC), and ability to detect failure (DET). Each of these items is evaluated on a 1-10 scale. A description of what constitutes a specific rating is given in the table below (adapted from Kremer, 2008).

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Rating Severity (SEV) Occurrence (OCC) Detection (DET) 1 Still works, no

performance impact, no danger

No chance, lots of operating experience, low uncertainty

100% chance to detect and avoid

2 3 Still works, poor

performance, no danger

4 May work but almost useless, no danger

5 Inoperable, no danger Good information, no operation experience and minimal testing, design based on analysis (some chance of OCC)

Some chance to detect and avoid

6 Still works, small performance impact, some danger

7 8 May work but almost

useless, significant danger

9 10 Inoperable, very

serious danger Very poor information about loads & operating conditions, wild guess at models, no testing (100% chance of OCC)

No chance to detect and avoid

Figure 7.1.1: FMEA Ratings Key (Kremer, 2008)

The team used this rating system to find the problems with the largest impact on project success. An FMEA matrix was designed which listed every part and assembly and all of the possible failure modes for each part. As a team a rating was assigned in each of the three categories listed previously and calculated an RPN for every failure mode. RPNs less than 60 were determined to be low risk items that do not need to be corrected, scores from 60-120 were moderate-risk items that should be addressed but are not critical to project success, and scores greater than 120 were on items in which that mode of failure would lead to complete failure of the project. The initial FMEA matrix of ratings and scores is in Appendix A, and we determined that the failure modes of greatest importance were:

1. Bending of the Acme shaft due to repetitive loading. 2. Friction buildup on the Acme threads over time. 3. The jig is too complex or difficult to use for our customer.

We followed up on the first two items with calculations and experimental testing, and the third item was tested directly by customer feedback on a mock-up and our prototype.

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From the FEA of the worst-case loading of the rod with the y-adjustment fully extended in the center of the rod, the maximum stress was found to be 25ksi. This is within a safety factor of 1.8 compared to the yield strength of the steel. With an approximate fatigue strength of 26ksi there could be a cause for concern for fatigue failure, but not until after many years of use. The customer will not reach the number of cycles needed to injure the part, and this is the worst case loading, which will not occur on a regular basis. In normal loading situations, the T-slider will not be fully extended and will not be in the center of the rod, and this will lead to lower bending stresses on the rod. See section 4.6 of the attached ME 451 report for full details, along with the first FMEA worksheet. To address the possibility of friction buildup on the threads of the shaft and nut, we performed an experiment to determine how much force is required to turn the shaft to adjust in the x direction. The original channels in the plastic plate were not wide enough for the bracket to easily slide through, and as a result the force readings were about 10 N on the handle when travelling from the center to the right side of the x-adjustment. We followed up by filing down the edges of the channels until the the right side had the same ease of motion as the left, which led to an input force of about 1 N to turn the handle. Please see the attached ME 488 report for further details, along with the second FMEA worksheet. When we returned to SW Resources for customer feedback on the mock-up we learned that we had made an unnecessary design assumption up to that point. Bob originally had requested that the adjustment be in ¼ inch increments, but what he intended by that comment was that he wanted to be able to adjust the position down to at least ¼ inch, and that specific measurements were not required. He would simply take one pre-labeled piece of mail and use it to adjust the jig to the correct position by lining it up with the label. The third FMEA focus item was associated with the ability of the jig to communicate its position with tactile cues such as measurement of distance, but from the customer we determined that the device was simple enough to meet his requirements. Please see the third FMEA worksheet for full details on the scoring of this item.

Failure Mode Initial RPN Corrective Action Final RPN Fatigue 175 FEA 70 Friction 224 Experiment 80

Difficult to Use 160 Customer Feedback 16 Figure 7.1.2: FMEA Results

7.2 Design and Construction The design of the prototype was done in a visual manner using solid edge. The software was used to model parts so that each team member could visualize and understand the function of the various parts. Based upon the modeling and availability of parts, the design decisions were made. Initially the Acme screw and nut system was chosen because the pitch of the Acme rod could be chosen so that one turn of the rod would result in a quarter inch of x-adjustment. The Acme system would provide a reliable and easy way to adjust the jig. For a blind user, keeping the adjustment device (the knob) in the same place all the time reinforces the ease of use and

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memorization of setup steps. The Acme system also allows for a very smooth and precise positioning system. The steel tube frame was designed to be large enough to encase the Acme rod and nut. The Acme rod was chosen and modeled based upon the pitch criteria. The Acme nut was designed to slide within the steel tube frame, and connects to the y-adjustment assembly. A side view of the Acme system is shown below in Figure 7.1. At first the steel tube was modeled to only have a 1/16th inch clearance on both sides of the Acme nut, but the steel tube that was purchased was actually 1/8th inch wider and taller than desired, but we decided that this size would still work and updated the model to match the material purchased.

Figure 7.1: Side view of Acme system

The Acme shaft was designed as shown in Figure 7.2 below. The Acme screw was designed with the counsel of Randy Mulford. Randy assured the team that the CNC lathe and tooling available would work to manufacture our design. The shaft was dimensioned to be held by a pair of bushings and the ends are chamfered to allow for easy assembly of the bushings. The diameters of the ends of the Acme screw are machined down to provide a smooth rotational surface, and to provide a thrust resisting surface with the bushings keeping the assembly together.

Figure 7.2: Acme screw design (Threads are left out for simplicity)

Acme Nut Acme Rod Steel Tube (with the   top cut off) 

Acme  Threads Chamfers (on  both sides) 

Ends turned down for bushings (on both sides)

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Next the Acme nut was designed. The geometry of the part was based upon the purchased part shown in Figure 7.3 left. The part was cut down into a square to fit into the steel tube, and also has two tapped through holes and cutouts to support and connect the legs of the y-adjustment bracket. The nut was designed to be made with a CNC machine. The CNC is the best and easiest way to make the complex features such as the squaring off of the sides, the grooves on the sides, and the two tapped holes through the part.

Figure 7.3: Acme nut, on the left as purchased, on the right as machined.

(Threads are left out for simplicity)

Next the bushing seats were modeled as shown in Figure 7.4 shown below. The bushing seats provide an interface between the bushings and the supporting steel frame, and also connect and align the plastic labeling surface to the assembly. The bushing seats sit inside the steel tube, and contain couterbore holes that are the size of the bushings. The tapped holes are placed so that they contain enough material between the various holes to prevent fractures or tears. This part was designed to be cut out of a solid piece of 1”x1”x12” aluminum used for both seats. This part was designed to be made with a CNC machine.

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Figure 7.4: Bushing seat design (wire view)

Next the labeling surface was designed as shown in Figure 7.5. The material for both the plate and the vertical and horizontal stops were cut out of the same 24”x 24” piece of white Delrin plastic. The two slots in the plate were machined with a CNC, and the holes are all drilled with a drill press. All of the holes on the labeling surface and stops are countersunk so that no piece of mail will become stuck on a screw, or cause injury to the operator. All edges of the plastic were chamfered or softened with a plastic shaving tool.

Figure 7.5: Labeling surface design.

Next the steel tubes of the frame were designed and are shown in Figure 7.6 below. The tubes were designed to be cut with a band saw, and drilled with a drill press, and then welded together. The tube that contains the Acme rod shown in black has the top cut off, but the other three tubes

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have to bottoms cut of, to the same height, so that the plastic labeling surface can be connected with countersunk screws and nuts to a flat surface.

Figure 7.6: Steel frame design.

The last part of the prototype to reach a final design and to be built was the y-adjustment assembly. The aluminum connection bracket shown below in Figure 7.7 was designed to be made with a CNC machine. The part was designed to be machined from the same 1”x 1” x 12” solid aluminum as the bushing seats. In order for the y-adjustment to be stable, two legs and four countersink screws connect the bracket to the Acme nut below the plastic plate. The bracket maintains the alignment of the T-sliders within the assembly by the channel machined through shown in the y direction in Figure 7.7. The two tapped holes at the top of the bracket are used to connect the clamp plate to the bracket. Also note that the right side of the bracket clamp support is lower than the left so that the clamp maintains contact with the T-slider and “clamps down” the adjustment for the user.

Figure 7.7: Bracket design.

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Next the two different T-sliders were designed and constructed as shown in figure 7.8 below. The T-sliders were originally made from aluminum, but they were changed to PVC after noting a poor abrasive surface between an aluminum T-slider, and the aluminum bracket. The T-sliders were designed to be made with a CNC. The short T-slider is used for labeling positions less than 2.5 inches away from the horizontal stop. The long T-slider is used for labeling further, but not used from 0 to 2.5 inches because it could stick into the users’ body. The T-slider has 3 4-40 threaded holes that will connect to the bendable labeling plastic with the common screws throughout the assembly. The stop on the underside of the part is designed so that the bendable plastic can be placed square and the holes drilled after placement. Also, this stop allows the jig to be adjusted all the way back to 0 inches in the y direction without interference between the assembly and the screws and bendable plastic.

Figure 7.8: T-slider design. (Long version)

Other parts in the design are of direct consequence of the previous decisions made. The aluminum clamp was designed to fit onto the bracket. The legs were an additional add-on requested by the customer to incline the labeling surface. The legs were designed to fold and hide inside the assembly if desired. The construction of the prototype began even before all of the design details had been decided. The parts of the prototype that had been finalized were completed first. The prototype construction began in the 5th week of winter quarter and was completed for delivery in the 10th week of winter quarter. The various materials and parts for the prototype were purchased predominantly through McMaster.com. During the design process the use of this website was used to bridge the gap

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between what we wanted, and what was available. The prototype bill of materials shown in Appendix E

7.3 FEA validation

A finite element analysis was preformed to validate sizing of the parts in the design. The analysis shows that a force of 80 lb pulling upward on the aluminum bracket will cause a maximum stress of 3 ksi, which is much less than the yield strength of 6061 Al which is 31 ksi and the fatigue strength is 10 ksi. A FEA was preformed for an aluminum T-slider also, but we have since changed the material for this part to PVC and further tests would have to be done to determine possible failure. A FEA was also preformed on the ACME screw with a 80 lb bending moment placed in the middle of the part. The maximum stress from the analysis was 25 ksi which is less than the yield stress of 45 ksi. A FEA was also preformed on the bendable labeling template, but as with the T-slider, the material was changed and further testing has to be done for the new bendable plastic. For a detailed FEA validation see Appendix C copy of the ME 451 report.

7.4 Prototype Experiments and Testing For prototype testing details see Appendix B copy of the ME 488 report. In order to assess how well the prototype works for the customer, we delivered the prototype and let the customer use if for a week. After the week, we returned and presented the following questions to Bob. Also, we preformed a time trial comparing the set-up time Customer Design Evaluation Questions Template:

a.) Is the material flexible enough?

Answer: Yes

b.) Are the edges an issue?

Answer: No

c.) Is the template width and length adequate?

Answer: No, the width is not wide enough and has to be as wide as a label, and he provided us with a label.

d.) Has any mail become snagged on the template?

Answer: No

X-Adjustment: a.) Is the adjustment the right speed?

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Answer: Yes

b.) Does the adjustment cause any physical pain?

Answer: No

c.) Is the adjustment smooth and accurate?

Answer: Yes

d.) Is the handle the right size?

Answer: Yes, Bob showed us how he used his thumb to turn the knob, which is easier that using the entire hand as we had done.

Y-Adjustment: a.) Do the thumb screws work well?

Answer: Yes

b.) Does the T-slider stay in place?

Answer: Yes

c.) Does the T-slider adjust smoothly?

Answer: No, we told Bob that this would be addressed because the aluminum T-slider would be changed to a different material.

d.) How do you want to store the additional T-slider?

Answer: No storage necessary.

Comfort: a.) Does any aspect of the design cause discomfort?

Answer: No

Setup Time Comparison Test: a.) Test each jig with two positions. b.) Video tape the test. c.) Evaluate the time it takes with each jig from the video. d.) Determine setup time.

Told = 100 sec. Tnew= 30 sec. Comments:

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The customer expressed great satisfaction with the design with only a few minor improvement suggestions. To quote Bob, there is “no comparing” the difference between the old jig and the new one.

8.0 Design Refinement for Production The team used the customer feedback on the prototype to continue to make design improvements for the final design. We also incorporated design for manufacturability (DFMA), design for safety (DFS), and cost saving measures into the final design for production. 8.1 Initial Design Development The effectiveness of the prototype was evaluated based upon a timed setup test by the customer. This was a basic time trial test that compared the setup time of the new device to the customer’s old method. The original device took approximately 100 seconds from the start of setup to apply labels to a piece of test mail. The newly designed device showed a large improvement by reducing the time of setup to 30 seconds. This test thus suggests that there is a significant improvement in set-up time over his previous jig. However more tests would need to be completed in order for this statement to be justified. Another improvement that the design addressed was the ease of use. This improvement is defined by the number and complexity of the steps required to operate the device compared to the steps required before the jig was implemented and is shown in Figure 8.1.1 below. Not only are there now fewer steps, but also the steps are easier to perform than in the previous process. For example, cutting the cardboard in the old process is much more difficult for a blind person than simply turning the handle to adjust the jig with the new process. Although our focus was to create a labeling device for the blind, people with other disabilities may now also use the jig. Persons with minor mental disabilities will find the new labeling steps from Figure 8.1.1 much easier to accomplish than those of the previous method. The previous labeling method requires the ability to sort through slightly differently shaped pieces of cardboard and even possibly the use of scissors and tape, but now people with other limitations or trouble using scissors will be able to do the job more safely and effectively.

Previous Labeling Steps New Labeling Steps 1.) Remove and discard old cardboard and

tape 1.) Put example envelope onto jig

2.) Put example envelope onto jig 3.) Cut cardboard to proper size with scissors

2.) Adjust template in horizontal direction

4.) Align cardboard with label and jig 5.) Clamp cardboard down to jig

3.) Adjust template in vertical direction

6.) Begin Labeling 4.) Begin labeling Figure 8.1.1: Previous and New Labeling Steps

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8.2 Design for Manufacturability After incorporating customer feedback into the design, the techniques of DFMA were used. Some of these techniques were incorporated when the prototype was being designed. For example, we standardized our fasteners so that only #4-40 machine screws, #10-24 bolts, and .25-20 shoulder bolts were used to assemble the template. Also the original rod supports were changed from bearings to bushings because bushings were easier to install and tight tolerances were not required. In order to lower material costs we manufactured the plastic plate and the perpendicular positioning strips from the same sheet of plastic.

In order to focus our efforts on specific area that could use improvement, we performed a pareto analysis for the parts, production processes, and then one that incorporated both of these. Each of the charts were made from their respective lists. These charts are shown below in Figures 8.2.1-3.

Figure 8.2.1: Original Materials Pareto Analysis

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Figure 8.2.2: Original Production Costs Pareto Analysis

Figure 8.2.3: Combined Pareto Analysis

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From this we used the idea that we should focus on the items that caused 80% of the costs. For the material analysis there were five items that we determined were worth our effort. They were the plastic plate, Acme nut, steel tubes, Acme shaft, and aluminum stock for the bracket. An initial area of discussion was the Acme nut/rod. The reason is that nut and the rod are high in cost because they are the Acme specification. If the Acme requirement was eliminated, then there would be a significant reduction in cost for materials. An initial analysis indicated that a regular rod would cost around $20 for stainless steel and around $5 for plastic. However, after looking at the cost for machining the new rod, the total price would be about the same (~$50).

A similar process was completed for the production costs. The top processes involved CNC work so most of the improvements to cost dealt with this. One issue was machining the ends for the Acme rod. This process was originally done on the CNC lathe, but since the operation is simple, this was changed to a regular lathe giving a total production cost reduction of about $20. Another process that was changed to the CNC was making of the bushing seats. The part only requires a drill press and belt grinder thus removing $56 of machining cost.

Similarly, the long slots in the plastic plate can be made using a conventional vertical mill rather than the CNC. The T-sliders can be rough cut on a vertical bandsaw and then smoothed with a grinder, and this eliminates another CNC process. Together, these changes result in savings of about $80 from the prototype fabrication processes.

Another idea that was considered was the removal of the welding steps by using L-brackets. However, when this was analyzed through our costing procedure, we found that the additional holes to be drilled in the steel tubes along with the new parts and screws added some production costs, and it came out to roughly the same amount of money. It is still an option for an additional jig to be manufactured, but the cost difference is only about $5.

The main reason the template cost as much as it did was because of the system used to move in the X-direction (Acme nut and rod). Every design aspect was then built upon this. Thus, without completely redesigning the system, there are few places where significant cost reductions can occur.

A final cost estimate was completed after implementing the changes described above. From this we see that the most of the savings occurred by changing the way parts were machined (CNC to conventional). Doing this gave savings of $214 which is a difference of 19.4% from the original machining costs. When the materials and production changes were included, there was total of $243 saved which was 17.6% off the original cost. See Figure 8.2.4 below.

Total Machining Cost: $888.03 Savings $214.29

% Savings off of original machining costs: 19.4%

Final Design Machining + Materials Cost $1,144.18 Prototype Machining and Materials Cost $1,387.85

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Savings from Prototype to Final Design in Material & Machining Cost $243.68

% Savings 17.6% Figure 8.2.4: Savings Summary

8.3 Design for Safety Safety was an integral part of our prototype design, so no further design refinement was needed to achieve a higher level of safety. All of the moving parts are encased in the steel channels and the plastic plate. For comfort and per our customer’s request, we changed the hex-head bolts to round heads to remove any sharp edges.

9.0 Final Design for Production

9.1 Design Description and Operation

The complete design assembly consists of three subassemblies. Figures 9.1.1 and 9.1.2 show the fabricated and computer generated finalized design.

Figures 9.1.1 and 9.1.2: Complete Assembly

The first subassembly (labeled the X-assembly) includes a four-component welded U-channel steel frame with the front tube concave up. This allows for the insertion of a steel/plastic Acme rod/nut system, two aluminum bushing seats and a plastic knob. Two PVC plastic legs are attached to the underside of the frame near the rear of the assembly to induce a 7 degree tilt of

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the entire piece. The Acme Nut is highlighted below because it is integrated into all subassemblies.

Figure 9.1.3: X-assembly

The second subassembly (labeled the Plate-assembly) contains only three parts made from the same plastic sheet. Two narrow strips that create a 90-degree corner atop the large base plate are fastened using screws. The type of plastic used was selected based on impact durability, low wear characteristics and low friction coefficient to handle a large number of items dropped and slid across the surface during a normal workday.

Figure 9.1.4: Plate-assembly

The third subassembly (labeled the Y-assembly) is attached using screws to the Acme nut in the X-assembly while inserted into the two slots (located in Figure 9.1.4) in the Plate-assembly using an aluminum bracket (shown below in black). A small aluminum piece is used to clamp down either of two plastic T-sliders of different lengths using two thumbscrews. A flexible plastic labeling template (shown below in orange) is screwed onto the end of each T-slider.

Slots for Bracket/Nut

Assembly Operation

Acme Nut

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Figure 9.1.5: Y-assembly

Once assembled into the complete assembly the device is ready for use and will be fully operational with very little maintenance. The operation of the jig begins with only one initial, optional set-up step. If the flat work surface is found to be uncomfortable, the user may flip out two sturdy legs into a position that tilts the surface to a comfortable angle of 7 degrees.

Figure 9.1.6: Leg Position

The piece of mail is now ready to be slid onto the top side of the jig. The user will need to ensure three things: that the mail is under the t-slider, the left and bottom sides of the mail are resting against the raised strips and that the mail is facing in the desired direction.

Acme Nut

Bracket

Template

Thumbscrews

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Figure 9.1.7: Mail Placement

The third operation aligns the label applicator with the label in the left and right directions. The Acme rod allows for full freedom across the bottom of the jig. This is very important so that the template does not supply any addition error in labeling accuracy.

Figure 9.1.8: Adjust X-Direction

Operation four aligns the label applicator with different labeling positions to and from the user. By simply loosening the right thumbscrew the t-slider can be adjusted in and out of the bracket to the necessary distance. If a label needs to be placed over three inches away from the bottom plastic strip, a long t-slider can be easily installed in place of the small one. However, this longer t-slider should be replaced by the alternate smaller one at short distances to ensure that the user does not encounter any discomfort from the long extension of the slider.

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Figure 9.1.9: Adjust Y-Direction

A few safety tips include: • When adjusting with the handle, keep all fingers and clothing away from the moving

slider so that nothing is pinched or caught in the device.

• Take care not to pinch fingers on the legs when retracting them from their storage position.

• Place on a level, dry surface.

Further instructions and safety measures are found in the User’s Manual in Appendix G. 9. 2 Manufacturing and Assembly 9.2.1 X-Subassembly In manufacturing the X-Assembly, first the Acme rod must be cut on a horizontal bandsaw to its length from stock. On a CNC or manual lathe, the threads on both ends of the rod must be turned down to the inner diameter of the bushing seats, followed by a finishing pass to ensure that the bushings do not wear quickly and have a low friction contact with the rod. An appropriately sized collet is acceptable to fix the rod in the lathe. Figure 8 in Appendix E is a fully dimensioned part manufacturign drawing. The two bushing seat parts require mostly CNC milling processes. After first cutting from aluminum stock with the horizontal bandsaw, the rest of the processes require CNC machining. The existing fixture on the mill can holds the seats well enough. The first task to machine is the pocket that the bushings sit in. because of the complex nature of the parts, the seats need to be repositioned twice to drill and tap the holes on the top and bottom of the seats accordingly. All tapped holes on the seats serve the purpose of either connecting to the frame assembly or the plate assembly. After fully machining the first bushing seat, the G-code program created can be

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repeated for the other seat, with the addition of an extra drilling process to allow for the Acme rod to travel through the seat. The Acme rod must extrude all the way through the seat so the handle can be assembled. Figures 10 and 11 in Appendix E provide the part drawings for both seats. A complete assembly drawing of the X-Subassembly is provided in Figure 19 of Appendix F. 9.2.2 Y-Subassembly The manufacturing of the Y-Assembly includes the most complex machining in the design. Machining of the bracket and threaded nut both require a number of CNC milling processes, while the T-sliders have more options in its machining depending on personal preference. All parts can use the existing fixture to place in the mill. To create the contour required of the nut, round side first had to be milled to a flat with the intention of creating a workable datum surface to position the part. According to the nut drawing, two drill holes are required on the flattened side surface of the nut with the purpose of connecting to the bracket, which straddles the nut from above. A full part drawing of the nut is provided in Figure 12, Appendix E. The aluminum bracket is the single most expensive and complex part to machine in this design. After cutting aluminum on a horizontal saw from stock, there are a number of CNC required processes to complete its manufacturing. Aside from the necessary tapped holes, there is extensive milling needed using an end mill. The top of the bracket is milled across the entire length to provide a rectangular pocket that the T-slider can slide into. The bracket also must be repositioned upside down to mill out the area where the bracket straddles the nut. This also allows the remaining legs to be thin enough to travel through the plastic plate. The bracket’s part manufacturing drawing is provided in Figure 9, Appendix E. A complete assembly drawing of the Y-Subassembly is provided in Figure 17 of Appendix F. To machine the two T-sliders, there is more than one option of manufacturing. For cheaper labor, all the processes can be achieved on a vertical and horizontal bandsaw, along with a drill press. In production, the T-sliders would be moved to a CNC Mill to speed up productivity. Figure 14 of Appendix E shows the fully dimensioned part drawing of the T-slider. 9.2.3 Frame/Plate Subassembly All tasks in the frame subassembly are simpler than many others required on the other subassemblies. All steel frame channels can simply be cut to length from stock with a horizontal bandsaw, and then cut in half longways on a vertical bandsaw. Assembling the frames together is achieved with welding, but could also be done with simple “L” shaped brackets and screws. The plastic plate that provides the work surface of the final design contains simple machining tasks, but the large size of the plate requires extra care and effort in setting up for machining. On a CNC mill, it requires removing the normal fixture from the work area, and clamping the plate to the CNC’s table. A vertical manual mill may be an easier alternative to machine the slots in

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the plate because of the extra mobility that can be achieved (mainly due to the lack of a protective housing around the work area). Once cut to size and the slots are cut, several drill holes are necessary from allow for attaching to the X-Subassembly and Frame Subassembly. A drill press with a large table and several clamps is required to set up and fix the plate well enough to perform. The part drawing for the plastic plate is shown as Figure 1 in Appendix E. The plastic strips to ensure a 90 degree surface for the mailings are machined from leftover plastic stock on a vertical bandsaw, and all drill holes are added on a drill press. The two strips, both slightly unique from each other, are shown in Figures 2 and 3 of Appendix E. A complete assembly drawing of the Plate Subassembly is provided in Figure 20 of Appendix F, while the Frame Subassembly is included with the X-Subassembly drawing previously referenced in Figure 19 of Appendix F. 9.2.4 Overall Assembly Overall, fasteners are universal across the design to cut down on costs and allow for easier machining. Successful assembly does require the assembling tasks to be done in a specific order to make sure the parts and assemblies all connect correctly. Specifically, the bracket and nut must be connected independently from their assemblies, and they must be fastened with the plate between them. From there, it is best to assemble the X-assembly around the nut, followed by adding all fasteners to the holes on the plate assembly. Figure 9.2.4.1 better shows the X-Assembly being attached to the plate. It also more clearly shows the Acme rod’s relationship with the bushing seats and handle. Figure 9.2.4.2 details some of the more intricate fastening needed assemble the Y-Subassembly with the X-Subassembly. A total jig assembly drawing is provided in Appendix F, Figure 18.

Figure 9.2.4.1

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Figure 9.2.4.2

9.3 Cost Estimation The following table details all cost estimations for future production of the design on a small scale (less than 10 units). The equation below the table the formula used for each production cost prediction. Each production operation includes an estimation of time and cost for all included machining tasks per machine. Included in the production costs are all stock material costs, labor, and estimations on overhead costs. No special operations or tolerances added extra costs to the production estimation. The overhead factor of the cost estimation is assumed to be 1 for all operations as a rule of thumb. Equipment factor accounts for the cost of powering and using any equipment without factoring any labor. Rental costs would also be included in this category.

Operation 1

Operation 2

Operation 3

Operation 4

Operation 5

Cut Plate to size and drill & CSK holes using jig fixture #1 per dwg #001

Cut Strips to size and drill & CSK holes using jig fixture #1 per dwg #002/003

Cut long groves into plate using CNC per dwg #001

Cut & Drill Steel Channels per dwg #004, #005, and #006

Weld steel frame together using jig fixture #2 per assembly dwg #xxx

time to complete operation 1 1 1 2 1

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in hours labor rate for operation 12 12 20 15 15 Labor Cost 12 12 20 30 15 Basic overhead factor 1 1 1 1 1 Equipment factor 0.5 0.5 0.5 0.5 0.5 Special operation/tolerance factor 0 0 0 0 0 Total Operational Cost 30 30 50 75 37.5

Operation 6

Operation 7

Operation 8

Operation 9

Operation 10

Cut and drill plastic legs using jig fixture # 3 per dwg #007

Cut and turn Acme shaft per dwg #008

Machine aluminum bracket using CNC per dwg #009

Machine both aluminum bushing seats using CNC per dwg #010 and #011

Machine ACNE Nut using CNC per dwg #012

time to complete operation in hours 1.5 0.75 3 2.5 2 labor rate for operation 12 15 20 20 20 Labor Cost 18 11.25 60 50 40 Basic overhead factor 1 1 1 1 1 Equipment factor 0.5 0.5 0.5 0.5 0.5 Special operation/tolerance factor 0 0 0 0 0 Total Operational Cost 45 28.125 150 125 100

Operation 11

Operation 12

Operation 13

Operation 14

Machine aluminum clamp with saw and drill press per dwg #013

Machine both plastic T-Sliders using CNC per dwg #014 and #015

Cut and drill holes into bendable plastic template per dwg #016

Assemble Entire Jig per assembly dwg's #017, #018, #019, #020

time to complete operation in hours 0.5 1 0.5 1 labor rate for operation 12 20 12 12 Labor Cost 6 20 6 12 Basic overhead factor 1 1 1 1

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Equipment factor 0.5 0.5 0.5 0.5 Special operation/tolerance factor 0 0 0 0 Total Operational Cost 15 50 15 30 A= Time of labor B= Labor Rate C = Labor Cost D= Overhead E= Equipment Factor F= special operations or tolerances Labor Cost ( C ) = A × B Total Operational Cost = C× (1 + D + E + F) The total production cost, with materials costs added to the above cost estimation is at $1038. Using the general 1:3:9 rule of thumb, the material costs to total production costs ratio is 1:4. This result is a good reality check to ensure the production is not glaringly more expensive than materials, which would require redesign. 9.4 Design Drawings, Part List and Bill of Materials For all parts that require any machining processes after purchase, the fully dimensioned and toleranced manufacturing drawings are provided in Appendix E. Included in Appendix F is a descriptive assembly drawing for each subassembly highlighted in section 9.2 of the report. Each assembly drawing also has a parts list imbedded onto the sheet with each part and fastener in the assembly included. The following two pages show the Bills of Materials, first for the prototype phase of design, and a finalized production ready Bill of Materials (BOM). In figure 9.4.1.2, the production BOM is color coded to highlight the changes made between the prototype and production stages. All yellow items are the same material and quantity used in Figure 9.4.1.1 for the prototype. Items highlighted red have since been removed from the design, while green items have been added.

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9.4.1 Bill of Materials For Prototype and Production

Item #  Item  Vendor & Part # 

Cost Per.  Qty. 

Material Cost 

% Total 

1  24 x 24 x .25in Plastic Plate  McMaster Part # 8573K75  $76.05 0.6 $45.63 16.0%2  .5‐8 x 1in ACME nut, plastic or bronze  McMaster Part #1349K15  $31.28 1 $31.28 11.0%3  1.25 x 1.25 x .125in Steel Square Tube x 6ft  Logan Welding Supply  $30.00 1 $30.00 10.5%

4  .5 ‐ 8 x 3ft ACME shaft, 1018 Steel McMaster Part # 99030A316  $29.49 1 $29.49 10.3%

5  1 x 1 x 12 in Aluminum Cube  McMaster Part # 9008K14  $10.73 2 $21.46 7.5%

6  .25 ‐ 20 x 1.375 Shoulder Bolts McMaster Part #94496A480  $4.51 4 $18.04 6.3%

7  .5 x .25  x 18in Plastic Plate  Cut From Item 5  $76.05 0.2 $15.21 5.3%8  .5 x .25  x 14.75in Plastic Plate  Cut From Item 5  $76.05 0.2 $15.21 5.3%9  PVC T‐Sliders  McMaster  Part #8747K115  $15.05 1 $15.05 5.3%

10  #10 ‐ 24 x 0.75in Hex Head Bolt McMaster Part # 94081A144  $2.51 4 $10.04 3.5%

12  0.5 OD x 0.313 ID Plastic Bushing  Mcmaster Part # 6377K27  $4.75 2 $9.50 3.3%

13 #4 ‐ 40 x 0.375in CSK Machine Screw (pack of 50) 

McMaster Part # 92210A127  $7.58 1 $7.58 2.7%

14  PVC Legs (1ft length)  McMaster Part #8660K39  $7.14 1 $7.14 2.5%15  Bendable Plastic Template  Hobby Lobby  $6.89 1 $6.89 2.4%

16  #4‐40 x .625 CSK Machine Screw McMaster Part # 90585A205  $5.88 1 $5.88 2.1%

17  Adhesive Rubber,3/4 wide x 36 x 3/32 tall  McMaster Part# 93755K43  $5.83 1 $5.83 2.0%

11  #10 Washer (bag of 100) McMaster Part #  91090A103  $3.79 1 $3.79 1.3%

18  #4‐40 Stainless Steel Nut McMaster Part #91841A005  $2.99 1 $2.99 1.0%

19  #4‐40 Thumb Screws  Lowe's  $2.34 1 $2.34 0.8%20  Brass #4‐40 CSK screws   Lowe's  $1.19 1 $1.19 0.4%

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21  0.375 ID x .04in Washer (pack of 10?)  Lowe's  $1.00 1 $1.00 0.4%

Figure 9.4.1.1 Prototype Bill of Materials

Item #  Item  Vendor & Part # 

Cost Per.  Qty. 

Material Cost 

1 #4 ‐ 40 x 0.375in CSK Machine Screw (pack of 50) 

McMaster Part # 92210A127  $7.58 0.32 $2.43

2  #10 ‐ 24 x 0.75in Hex Head Bolt McMaster Part # 94081A144  $2.51 4 $10.04

3  0.75 ID x .04in Washer  Lowe's  $1.00 4 $4.004  1.25 x 1.25 x .125in Steel Square Tube x 6ft  Logan Welding Supply  $30.00 1 $30.005  24 x 24 x .25in Plastic Plate  McMaster Part # 8573K75  $76.05 0.6 $45.636  1 x 1 x 12 in Aluminum Cube  McMaster Part # 9008K14  $10.73 2 $21.46

7  .5 ‐ 8 x 3ft ACME shaft, 1018 Steel McMaster Part # 99030A316  $29.49 1 $29.49

8  .5‐8 x 1in ACME nut, plastic  McMaster Part #1349K15  $31.28 1 $31.289  .5 x .25  x 18in Plastic Plate  Cut From Item 5  $76.05 0.2 $15.21

10  .5 x .25  x 14.75in Plastic Plate  Cut From Item 5  $76.05 0.2 $15.2111  0.5 OD x 0.313 ID Plastic Bushing  Mcmaster Part # 6377K27  $4.75 2 $9.50

12  #4‐40 x .625 CSK Machine Screw McMaster Part # 90585A205  $5.88 1 $5.88

13  #4‐40 Stainless Steel Nut McMaster Part #91841A005  $2.99 1 $2.99

14  Adhesive Rubber,3/4 wide x 36 x 3/32 tall  McMaster Part# 93755K43  $5.83 1 $5.83

15  .25 ‐ 20 x 1.375 Shoulder Bolts McMaster Part #94496A480  $4.51 2 $9.02

16  Bendable Plastic Template  Hobby Lobby  $6.89 1 $6.8917  PVC T‐Sliders  McMaster  Part #8747K115  $15.05 1 $15.0518  PVC Legs  McMaster Part #8660K39  $7.14 1 $7.1419  #4‐40 Thumb Screws  Lowe's  $2.34 1 $2.3420  Brass #4‐40 CSK screws   Lowe's  $1.19 1 $1.19

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21  L‐Brackets ‐ Type 3  McMaster Part 1556A17  $1.51 4 $6.0422  #10‐24 x0.75" Round Head Bolt (pack of 100)  McMaster Part 90279A245  $4.42 1 $4.42

23  #10 Washer (bag of 100) McMaster Part #  91090A103  $3.79 1 $3.79

24  #10‐24 Nut (bag of 100) McMaster Part#  90480A011  $1.54 1 $1.54

Figure 9.4.1.2 Bill of Materials for Production

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10.0 Conclusion The objective of this design project was to decrease the time and outside help needed to set up a new labeling position. The design needed to allow for all mail and label sizes that would be encountered with one template. Safety, comfort and ease of use were also important factors in the design that would finally lead to increased productivity and a better working environment. The feedback obtained from the customer concluded that all objectives were met if not exceeded. The amount of time taken to set up the workspace was reduced to less than a third of the original time, outside help was decreased to a minimum and the design is easier, safer and more comfortable to use. The design objectives were at the forefront of all decisions affecting scheduling and project costs. Before purchasing any materials, the parts were modeled and assembled in a solid modeling program to validate the design concept.

Jig Value Units Achieved

*Size ≤ 16 Inches

*Stop Strips Dimensions

1x ¼ Inches

*Adjustability

0-4 Inches

*Adjustability

16 Inches

*Increments

¼ Inches

*Corner Stop 90 Degrees

Drop Height Durability

4 Feet -

Expected lifetime 5-10 Years TBD

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Affordability <$200 USD Cost Analysis

Weight <10 Pounds

Corrosion Resistance Close Materials

Galvanic Scale -

Template Deflection ¼ Inches

Figure 10.0.1: Table of Specifications

From Table 10.0.1 we can see that the jig met most of the requirements thus the overall design is believed to be a success. The true value of the design is still something that need to be determined. As initial estimate, the jig is not believed to be of a great value. The main issue that was solved was decreasing the set up time required to label the mail. The jig is changed a couple of times a day, and is sometimes not used all days. Thus, based on the one experiment that was carried out, the jig would save roughly 1-3min of time for Bob. It should be noted that Bob found the new jig comfortable, but when weighing the time savings and increase in comfort, it is hard to justify the calculated price of $1144. The overall design, while it has proven to perform admirably when comapred to the customer’s specifications as well as our own, still must be looked at closer before an informed decision can be made whether or not to move forward for a larger scale production. Questions regarding its value as compared to its cost still exist. The materials costs and production costs have both gone down dramatically as the redesigns became the final design, but are still high enough to cause concern. Currently there are only plans for the production of one more product, but if our design were ever to be sold for profit, the suggested selling price would likely rise above $1,000 using the one-three-nine cost analysis used. If a decision ever is made to move forward with a larger scale production, further redesigns likely would be the only option to lower costs at the risk of a lower quality product. Aside from cost driven decisions on any redesigns before further production, the one area in which the project could be continued before advancing to the production stage is the possible addition of a storage system of the extra T-slider when it is not in use. The easiest, and cheapest option likely would be an adjustable velcro strap attached to the bottom of the platic labeling plate, similar to the adjustment on a velcro gym shoe or sandal.

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References Americans with Disabilities Act (ADA). Department of Justice ADA Title III Regulation 28

CFR Part 36. (2002) http://www.ada.gov/reg3a.html#Anchor-Appendix-52467 Allen, George. Label Applicator. Label Aire, Inc., assignee. (1997). US Patent 5853530. Assistive Technology Solutions. Rubber Band Applicator (11-16-2008)

http://www.atsolutions.org/devices/rubberband_applicator.htm Avery Dennison Corporation. (11-19-2008). http://www.avery.com/avery/en_us/Templates-

%26-Software/Software/Quick-Peel-Automatic-Label-Peeler-Support.htm?Ns= Frobose, James W. Push Button Adjuster for Chair Backrest. Jasper Corporation, assignee. (1980). Patent

4221430. Garvey Products, Inc. (11-16-2008) http://www.garveyproducts.com/index.php?main_page=

product_info&cPath=3&products_id=2537 House, Bruce F. Adjustable Self-Leveling Plate Dispenser. Shelley Manufacturing Company, assignee.

(1976). US Patent 3937361. Karp, Edward C. Manual Label Applicator. Sanitary Scale Company, assignee. (1986). US Patent

4626313. Originals by Weber. Label Peeler. (11-16-08). http://www.yrret.stirsite.com/page/page/

3920328.htm Pfeffer, George B. Manual label applying template. Datafile Limited, assignee. (1983). US Patent

4369582. Suhr, Heinz-Peter, and Bernd Weinberger. Adjusting Mechanism for the Step-wise Locking Height

Adjustment of Backrest of Work Chair. Firma August Froscher GmbH & Co. K.G., assignee. (1987). US Patent 4660885.

SW Resources. Mail Plus Department. (2008). http://www.swresources.com/html/mailplus.html

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Appendices Appendix A – FMEA………………………………………………...73 Appendix B – ME 488 Report – Experimental Testing……….……81 Appendix C – ME 451 Report – Finite Element Analysis……..…...94 Appendix D – Executive Summary/NISH Report…………….……123 Appendix E – Part Drawings………………………………………...129 Appendix F – Assembly Drawings and Bill of Materials…...………145 Appendix G – User’s Manual…………………………………...……148

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Appendix A: FMEA

Part Name

Description of Operation

Potential Failure Mode

Potential Effect of Failure

SEV

Potential Cause(s) Mechanism(s) of Failure

OCC

Current Controls Detection/ Prevention

DET

R P N

Recommended Action

Acme threaded rod

Supports the travel of X-adjustment mechanism

Rod bends over time

X-travel difficult to non-functional

5 Fatigue wear 5 Part selection, Loading analysis 7 175

Perform fatigue analysis of repetitive load from weight of user's arms

Bearings - 3/8" x 7/8" x 0.28"

Allow threaded shaft to rotate freely

Bearing seizure X-adjustment difficult to impossible

5 Bearing failure 5 Part selection 3 75 Locate reliability of bearings from manufacturer

Bearing Seats

Hold bearings in place

Disengage from bearing

Bearings unattached, inoperable

5 Poor design, too much stress 6 Solid Modeling,

Part selection 3 90 Perfrom simple analysis of loading on bearing seats

Oxidation and wear

No longer covers mechanism, minor hazard to user

6 Chemical/Mechanical wear from hands 5 Material

Selection (Al) 3 90

Perfrom simple analysis of loading on square tube with comparison to strength of material

Square Tube

Covers the X-adjustment mechanism to prevent exposure to customer, surroundings

Raised up or sticks out too far, causing repetitive injury to user by impeded or forced motion

Operable but not ergonomically sound

6 Poor design 3 Solid Modeling 6 108

Send mockup to customer for feedback before final prototype fabrication. Possible solutions include changing loaction of rod and raising the back edge.

Machinable Nut

Part that moves with shaft rotation, holds Y-adjustment mechanism

Increased friction on Acme threads

X-travel difficult to non-functional

4 Insufficient lubrication 8 Rod has been

oiled 7 224 Investigate lubrication schemes for the threads and apply best solution

Sticks up too high

Impedes user's motion, inconvenience

3 Poor design 4 Solid Modeling, Mock-up 3 36 Construct mockup to

scale Connecting Bracket

Prevents rotation of machinable nut and connects Y-adj. mech. To X-adj. mech. Fracture

Inoperable; can't set Y-adjustment

5 Fatigue wear from internal stress; Drop fracture

2 Material selection (Al), Solid modeling

8 80 Perform FEA on part, get friction information on rod from testing

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Plastic Tab

Bends down to plate to assist in placing label.

Fatigue Failure

Cracks off at fasteners, or permanent deformation impedes placement of mail

5 Repeated pressing down by user 5 Part Selection 3 75

Find fatigue loading properties for material selection

Not rigid enough Difficult to use, reduced accuracy

3 Counterweight on the overhanging end 6

Tight tolerances, flush mate against bracket face

3 54 Construct mockup to scale

Sticks out too far and bumps into stomach of user

Possibly cause discomfort or repetitive injury to user

6 Design for fully retracted position sticks out too far

6

Second attachment for full four inch adjustment, current design only goes out 2"

2 72

Place jig assembly off the edge of the table a sufficient distance, send mockup to customer for feedback

T-Slider

Plastic Tab is attached to one end; this part adjusts in Y-direction in 1/4" increments

Difficult for blind user to know where he is on the scale

Inaccurate placement, needs extra help to set up

4 Inability of user to locate the correct position

8 Holes on side of T-Slider 5 160 Construct mockup to

scale

Difficulty in counting rotations

Inaccurate placement, needs extra help to set up

4

Lack of communication to user of complete rotation

1 One turn = 1/4" 5 20 Customer stated that it is not a problem.

Handle

Part that user interacts with to adjust X location, rotates Acme threaded rod Falls off

Inoperable, could cause minor injury

6 Not sufficiently connected to Acme shaft

2 Solid Modeling, Part selection 2 24 Complete part selection

and modeling of handle

Shear due to excessive force

Inoperable; can't set Y-adjustment

5 Excessive force on the T-slider 2 Choose a strong

material for pin 7 70

Choose a strong material for pin, make pin wide enough, testing Pin

Quick release pin locks the Holy T-Slider in place

Pin is lost Inoperable; can't set Y-adjustment

5 User Error 6 Finger ring on pin 4 120 Attach pin to cord, have extra pin

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Failure Modes and Effects Analysis for Safe, Reliable, Effective Designs Step1: Provide a description of the full system including all subsystems and accessories in all modes of operation (including storage, setup, transportation, operation, cleaning, maintenance, etc.). If possible please include sketches with users in operating positions for the main operating modes. This information can be included here or as an attachment to this document. See attached executive summary/NISH report. Step 2: Identify all potential failures and safety hazards for the system in each mode of operation. A failure is any undesirable occurrence associated with the system. If multiple failure modes have a common root cause, please compile them together and identify the root cause.

1. Fatigue wear causes bending of the Acme-threaded rod over time. 2. The acme threads have friction buildup from lack of lubrication. 3. The jig is too difficult or uncomfortable for the customer to use.

Step 3: For all significant potential failure modes in step 2, complete an FMEA table to determine the type of action necessary to achieve acceptable risk level, and the priority of the action compared to the other failure modes.

Potential Failure 1 - Fatigue wear causes bending of the Acme-threaded rod

Operating mode when failure could occur Potential Failure Mode When the user adjusts in the x-direction The rod is bent from repetitive loading by

the user on the plastic tab. Initial

Evaluation After Action

Results Potential Effect of Failure (Severity, SEV) 5 5

Potential Cause(s) / Mechanism(s) of Failure

(Probability of occurrence, OCC) 5 2

Current Controls for Detection and Prevention

(Probability that failure is detected and prevented, DET)7 7

Risk Priority Number (RPN=SEV*OCC*DET) 175 70

1. Include some discussion/justification for the rating for severity (SEV)

The x-adjustment would become gradually more difficult to use until the rod becomes so warped that the jig would cease to be useful. There is no hazard to the user.

2. Include some discussion/justification for the rating for probability of occurrence (OCC) When the user presses the end of the plastic tab down to the work surface a moment is being placed on the acme rod. After feasibly thousands of cycles of loading and

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unloading there could potentially be fatigue wear of the acme rod. 3. Include some discussion/justification for the rating for probability of detection (DET)

It is unlikely that this mode of failure would be detected until the rod was already bending. The rod could be replaced, but not easily.

4. Recommended actions to achieve acceptable risk: Make specific recommendations for action and include some discussion of the alternatives that were considered, the person(s) responsible for completing the actions, and the completion date.

We attempted to assess the loading on the acme rod analytically, but determined that a more accurate fatigue analysis could be performed using finite element analysis. Darren did the FEA on the acme rod, and this was completed on 2/25/09. We determined the force required to push the plastic tab to the work surface was about 25 lb, and then used this as a point load on the fully extended T-slider positioned at the center of the acme rod, as this would be the worst case loading scenario. The force on the tab was reacted by the rod as an upward force. The load on the rod was compared with the fatigue limit of the material, 1018 steel.

5. Notes on Completed Actions: The FEA determined that the loading of the worst-case scenario described above slightly below the fatigue limit of the material with a factor of safety of 1.8. However, from conversations with the customer, it was determined that the jig would not normally be used in that position, and therefore the normal loading would be much less. This allowed us to downgrade the likelihood of occurrence from a 5 to a 2, because it was no longer seen as a likely problem.

Potential Failure 2 - Friction buildup on the Acme threads

Operating mode when failure could occur Potential Failure Mode When the user adjusts in the x-direction The handle becomes too difficult to turn

because of friction buildup over time. Initial

Evaluation After Action

Results Potential Effect of Failure (Severity, SEV) 4 4

Potential Cause(s) / Mechanism(s) of Failure

(Probability of occurrence, OCC) 8 5

Current Controls for Detection and Prevention

(Probability that failure is detected and prevented, DET)7 4

Risk Priority Number (RPN=SEV*OCC*DET) 224 80

1. Include some discussion/justification for the rating for severity (SEV) The x-adjustment would become gradually more difficult to use from a buildup of friction on the acme threads. There is no hazard to the user, but the jig would be nearly inoperable.

2. Include some discussion/justification for the rating for probability of occurrence (OCC) Lubrication schemes were not originally considered in the conceptual design, but it was

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brought to our attention by Tyler, the TA. We were not sure what an acceptable threshold of force required to turn the rod would be, and what the current design requires to move the x-adjustment. We did not intuitively expect this to be a problem, but did not have sufficient proof to be sure. We initially oiled the rod, but it may wear off eventually.

3. Include some discussion/justification for the rating for probability of detection (DET) It is unlikely that this mode of failure would be detected until the threads were already becoming too difficult to turn. The casing would have to be opened to clean the rod and lubricate with oil.

4. Recommended actions to achieve acceptable risk: Make specific recommendations for action and include some discussion of the alternatives that were considered, the person(s) responsible for completing the actions, and the completion date.

We would use our ME 488 test on the amount of force required to turn the rod to overcome the friction as a baseline for whether we needed to investigate further lubrication schemes. Everyone who was in 488 was responsible for testing, which is all team members except Dom and Darren. Testing was complete by 2/26/09.

5. Notes on Completed Actions: The 488 test showed that the force required to turn the rod was very small (<1 lb), and that the human threshold for being able to turn a handle by hand is around 15 lb, according to research. We judged this to be acceptable proof that this mode of failure is unlikely. We included instructions in the user manual on how to lubricate the rod if turning becomes more noticeably difficult. These actions decreased the likelihood of occurrence from an 8 to a 5 because we had some test data to show that it was not a likely problem. We also decreased the detection score from a 7 to a 4 because of the instructions in the user manual.

Potential Failure 3 – Difficult Usage

Operating mode when failure could occur Potential Failure Mode Setting up the jig for labeling The user does not understand his location

on the jig, requiring extra help to set up. Initial

Evaluation After Action

Results Potential Effect of Failure (Severity, SEV) 4 4

Potential Cause(s) / Mechanism(s) of Failure

(Probability of occurrence, OCC) 8 2

Current Controls for Detection and Prevention

(Probability that failure is detected and prevented, DET)5 2

Risk Priority Number (RPN=SEV*OCC*DET) 160 16

1. Include some discussion/justification for the rating for severity (SEV) If it is too difficult for the user to understand where he is on the jig he would need outside assistance to set it up, which would defeat one of the main goals of our design, which is to establish independence for the user in performing his job. The jig would be of little use

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to the user, but would not present a safety hazard. 2. Include some discussion/justification for the rating for probability of occurrence (OCC)

We had few tactile cues on the jig for the user to understand where his position was on it. The acme rod translated motion ¼” with each turn, and our pin & slider y-adjustment had holes spaced ¼” apart. We thought it might have been too difficult for our customer to locate where he was on the jig without any kind of ruler or other cues to help him find the correct position. We had not yet received customer feedback on the issue, so we did not know whether or not it was a problem.

3. Include some discussion/justification for the rating for probability of detection (DET) It was difficult to know whether this would be a problem without first gaining some operating experience and feedback from the customer. It took a long time for us to reach our customer for communication.

4. Recommended actions to achieve acceptable risk: Make specific recommendations for action and include some discussion of the alternatives that were considered, the person(s) responsible for completing the actions, and the completion date.

The team brought a mock-up constructed by Rob for his feedback on the general layout on 2/11/09.

5. Notes on Completed Actions: It was determined from Bob’s feedback on 2/11 that we made a fundamental oversight in our customer’s specifications. Bob originally had requested that the adjustment be in ¼ inch increments, but what he intended by that comment was that he wanted to be able to adjust the position down to at least ¼ inch, and that specific measurements were not required. He would simply take one pre-labeled piece of mail and use it to adjust the jig to the correct position by lining it up with the label. This changed the way we approached the y-adjustment, because we were overdesigning for accuracy. We removed the pin and holes from our design and instead chose to clamp down the slider in order to simplify our design. The customer feedback was very positive, and he did not relate any problem with positioning the labeling template. This reduced the likelihood of occurrence to 2 and ability to detect the problem to 2.

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Part Name

Description of Operation

Potential Failure Mode

Potential Effect of Failure

SEV

Potential Cause(s)Mechanism(s) of Failure

OCC

Current Controls Detection/ Prevention

DET

RP N

Completed Actions/ Results

Acme threaded rod

Supports the travel of X-adjustment mechanism

Rod bends over time X-travel difficult to non-functional 5 Fatigue wear 2 Part selection,

Loading analysis 7 70 FEA showed acceptable stress in rod

Bearings - 3/8" x 7/8" x 0.28"

Allow threaded shaft to rotate freely

Bearing seizure X-adjustment difficult to impossible

5 Bearing failure 0 Part selection 3 0 Replaced with bushings

Bearing Seats

Hold bearings in place

Disengage from bearing

Bearings unattached, inoperable

5 Poor design, too much stress 2 Solid Modeling, Part

selection 3 30 Testing showed low internal stresses

Oxidation and wear No longer covers mechanism, minor hazard to user

6 Chemical/Mechanical wear from hands

3 Material Selection (Al) 3 54

Testing showed low internal stresses

Square Tube

Covers the X-adjustment mechanism to prevent exposure to customer, surroundings

Raised up or sticks out too far, causing repetitive injury to user by impeded or forced motion

Operable but not ergonomically sound

6 Poor design 1 Solid Modeling 2 12 Customer stated that it is not a problem.

Machinable Nut

Part that moves with shaft rotation, holds Y-adjustment mechanism

Increased friction on Acme threads

X-travel difficult to non-functional 4 Insufficient

lubrication 5 Rod has been oiled 4 80 Testing showed no need for lubrication

Sticks up too high Impedes user's motion, inconvenience

3 Poor design 4 Solid Modeling, Mock-up 3 36

Customer stated that it is not a problem. Connecti

ng Bracket

Prevents rotation of machinable nut and connects Y-adj. mech. To X-adj. mech. Fracture Inoperable; can't set

Y-adjustment 5 Fatigue wear from internal stress; Drop fracture

2 Material selection (Al), Solid modeling 4 40

Testing showed low internal stresses

Plastic Tab

Bends down to plate to assist in placing label.

Fatigue Failure

Cracks off at fasteners, or permanent deformation impedes placement

5 Repeated pressing down by user 5 Part Selection 3 75 Replaced with

stronger plastic

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of mail

Not rigid enough Difficult to use, reduced accuracy 3

Counterweight on the overhanging end

6 Tight tolerances, flush mate against bracket face

3 54 Replaced with stronger plastic

Sticks out too far and bumps into stomach of user

Possibly cause discomfort or repetitive injury to user

6 Design for fully retracted position sticks out too far

6

Second attachment for full four inch adjustment, current design only goes out 2"

2 72 Customer stated that it is not a problem.

T-Slider

Plastic Tab is attached to one end; this part adjusts in Y-direction in 1/4" increments

Difficult for blind user to know where he is on the scale

Inaccurate placement, needs extra help to set up

4 Inability of user to locate the correct position

2 Holes on side of T-Slider 2 16

Customer stated that it is not a problem.

Difficulty in counting rotations

Inaccurate placement, needs extra help to set up

4

Lack of communication to user of complete rotation

1 One turn = 1/4" 2 8 Customer stated that it is not a problem. Handle

Part that user interacts with to adjust X location, rotates Acme threaded rod Falls off Inoperable, could

cause minor injury 6 Not sufficiently connected to Acme shaft

2 Solid Modeling, Part selection 2 24

Shear due to excessive force

Inoperable; can't set Y-adjustment 5 Excessive force on

the T-slider 0 Choose a strong material for pin 7 0 Removed from

design Pin

Quick release pin locks the Holy T-Slider in place Pin is lost Inoperable; can't set

Y-adjustment 5 User Error 0 Finger ring on pin 4 0 Removed from design

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Appendix B: ME 488 - Preliminary Report on Torque Required for Rotational Motion of a Rod

Abstract This experiment investigates the relationship between the torque required to turn an Acme threaded rod, and the forces that oppose that motion. The results of this experiment are important to the integrity, ergonomically and structurally, of a label template jig. The torque will be applied by means of a crank or handle fixed on one side and the opposing forces are the result of friction between the parts of the attached piece and its environment. The rod’s purpose in the jig is to provide the user with an easy means of moving the label locator in the x direction. Attached to the rod is a nut which in turn is attached to an additional mechanism that controls the y directional movement of the label locator. This jig is designed to be used by a vision impaired user. To accomplish ease of use, the torque found must be low enough so that the user finds smooth and effortless function. If this objective is not accomplished the project will be considered a failure. Furthermore if the forces are unreasonably high between different parts of the jig, specifically those involved within the mechanism included by the rod, the jig may fail due to high stresses. To measure the torque required to begin rotational motion of the rod, the basic principles of torque will be used. As torque is equal to the product of a force and a distance, the handle is an opportune place to test this torque. A string was wrapped around the end of the shaft and was pulled at a nearly constant rate with a force gauge. The output from the force gauge was plotted in a table so that the results could be easily viewed as a function of time. From the graph the average force needed to operate the jig was obtained. The torque is calculated by multiplying this force with the distance between the end of the string and the central axis of the rod. Table of Contents Title………………………………………………………………………………………………….…..i Abstract…………………………………………………………………………………………………ii 1.0 Introduction

1.1 Objective………………………………………………………………………………...4 1.2 Background and Literature Review…………………………………………….…....4-6

2.0 Discussion 2.1 Specific Aims………………………………………………………………..……….6-9 2.2 Significance………………………………………………………………….…..….9-10 2.3 Experimental Procedure……………………………………..…………….………10-11

3.0 Results………………………………………………………………………………...…….11-17 4.0 Uncertainty Analysis……………………………………………………………………….17-18 5.0 Conclusions…………………………………………………………………...……………18-19

6.0 Bibliography………………………………………………………………………….………..19

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1.0 Introduction

1.1 Objective The objective of the experiment is to determine the usability of the jig by measuring the torque required to overcome the frictional resistance in the assembly. The torque required to start turning the knob will be related to the static friction coefficients between the materials and the geometry of the materials.

Figure 1: Jig Assembly

1.2 Background and Literature Review Friction is the force that opposes motion when two surfaces are brought in contact. Friction “…arises from the attraction of molecules between two surfaces that are in close contact [1].” There are two types of friction that are of interest to this experiment and they are static and kinetic friction. When a body is sitting at rest on a material, it takes a certain force to overcome the attraction of the molecules. The force that opposes the force applied to the body at rest is called the static friction force and is given by:

(1.1)

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In Equation 1.1 is the static coefficient of friction and is the normal force. When the body is in motion, an applied force is required to keep it in motion. The force that opposes this motion is called the kinetic friction (Fk) and is given by:

(1.2) In Equation 1.2 is the coefficient of kinetic friction and is the normal force. There are two important conclusions that can be made from the above equations. From Equation 1.1, it should be noted that this is the maximum static friction force that can be applied. Thus if the applied force is less than , no motion will occur but the magnitude of the static friction force will be equal and opposite to the applied force. Furthermore, Equations 1.1 and 1.2 do not contain any area terms and thus static and kinetic friction do not depend on the surface area of the object in contact with the opposing material. The coefficients of static and kinetic friction are specific to the two materials that are in contact with one another. Because , the maximum force that the object will experience will come from overcoming the maximum coefficient of static friction. Thus when designing the experiments, the focus will be on determining the static coefficients of friction. There is already a wide library of known coefficients of friction between materials, however specific coefficients for friction between specific materials (i.e. 1020 AISI cold rolled steel and polyethylene) are difficult to locate. As a result general materials were assumed and used as base values to make sure the numbers obtained from experiment were appropriate. The results are shown below:

Table 1: μ of Different Materials

Material 1  Material 2   Aluminum  Plastic  .4[2] 

Steel  Plastic  .25[3] 

Plastic  Plastic  .5[4] 

Another reason for performing the experiment was to determine if the jig was easily operable by the user. In order to do so a range of input torques need to be determined. NASA has already done research on this topic and the maximum torque that can be applied are 13 N-m in supination (turning the palm upward) and 17 N-m in pronation[5] (turning the palm downward).

2.0 Discussion 2.1 Specific Aims Given the pitch of the Acme shaft, and the frictional material properties, the goal of this experiment is to verify a relationship between the torque and the anti-rotational normal force. The hypothesis of the experiment is that the torque will follow the relationship developed below, within the uncertainty of the experiment. From the following analysis it is expected that the torque will increase with an increase in pitch angle θ. Also, the torque will increase with an increase in frictional properties, and vice-versa. It is predicted that the normal forces on the sidewall of the plate will increase with an increase in angle and/or friction. The resistance to turning the Acme shaft is due to the friction between the steel Acme shaft and the plastic Acme nut, and the resistance between the nut and the plastic plate that it slides against. In order to

84  

analyze the relationships between these forces Free Body Diagrams of the Acme shaft and Nut are shown in Figures 2 and 3.

Figure 2: Free Body Diagram of Acme Shaft

Summing forces in the x and y directions for the shaft:

(2.1) (2.2)

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Figure 3: Free Body Diagram of Acme Nut.

Summing forces in the x and y directions for the nut:

(2.3)

(2.4) Solving for in terms of :

(2.5) Substituting and solving for :

(2.6)

(2.7) Using Equation 2.7 the torque on the shaft can be related to the normal force that the nut and bracket feel from the plastic plate. This data is important in the operation of the device and will affect the final design. If the experiment concludes that the torque must be reduced, then there are two design improvement options. Adding lubricant to the Acme screw and nut, increasing the radius of the applied force, and opening up the tolerances in the bracket slots are all options for reducing the required torque.

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2.2 Significance

The performance of this experiment is significant in the successful completion and delivery of the prototype, as well as the final product. A Failure Modes Effects Analysis revealed that the most critical area to assess would be the rubbing of the machinable nut against the slots running through the plastic plate. Also, it became clear that the amount of torque applied, which depends on the input force and length of handle selected, would be very important.

The experiment was designed and formulated based on those variables. If the friction between the nut and the plate is too high, wear will show on the slots of the plastic plate. Also, the friction force between the nut’s threads and the Acme threaded rod are significant. A plastic nut’s threads could strip over time if the friction is too great. Each of these variables directly affects the required torque applied to the handle.

The results of this experiment will impact several important decisions regarding the overall design of the labeling template. If friction forces between the nut and the rod or plate slots are too great, significant decision must be made on possible courses of action. Lubrication may be considered, or if it is still thought to be too great, a change of materials may be in order. Also the results of the friction, which in turn gives a result of required torque will greatly aid in the handle selection. The size and shape of this handle will have a direct correspondence with the required torque found in experiment.

2.3 Experimental Procedure The objective of the experiment is to determine the ease of use in turning the shaft of the X-mechanism and determine how this torque applies to counteract the different friction forces within the system. In particular, the overall input force will be measured for turning the shaft with only the nut attached and again with the entire system. Part 1: Input Force and the Machinable Nut

1. Place the Acme shaft in a vise with the contoured side facing up. Do not over tighten, as this may cause damage to the part, but ensure tightness is adequate to prevent motion.

2. Insert the machinable nut onto the Acme shaft near the middle of the rod.

3. Tape a string to the nut and wrap the string around the nut many times.

4. Attach the force gauge to a loop in the string.

5. Zero the force gauge and then pull the force gauge, unwinding the string at a slow constant rate.

6. Repeat the experiment 3 times and save the force data as a function of time recorded.

Part 2: Input Force and the Assembly 1. Assemble all parts to the prototype design.

2. Using the same approach as Part 1, tape and wrap a string around the Acme screw at the end where the handle will be used.

3. Adjust the nut all the way to the left.

4. Attach the force gauge to a loop in the string.

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5. Zero the force gauge and then pull the force gauge, unwinding the string at a slow constant rate, recording data from the left to the center of the adjustability

6. Repeat the experiment again going from the center to the right of the range of adjustability.

3. Results The next three figures show the results of the three experimental trials that were run in experiment 1. The maximum force is shown in each, which is the force required to overcome the static friction. The average input force is also shown to turn which is required to turn the shaft at a constant rate.

Figure 4: Input Forces with Maximum and Average Shown, Trial 1

Figure 5: Input Forces with Maximum and Average Shown, Trial 2

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Figure 6: Input Forces with Maximum and Average Shown, Trial 3

Table 1, shown below, combines the data from the three trials to come up with the significant data used for analysis. Shown are the average input force required to overcome static friction, as well as the average force to keep the shaft turning and the nut traveling along it.

Table 2: Average Forces for Trials

The following two plots show the input forces for the second experiment. These input forces were recorded as the Y-Assembly travels the entire length of the Acme rod in full assembly. The first plot travels from the far extreme left of the X-Adjustment to the middle of the shaft. The second plot travels where the first plot left off to the far right extreme.

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Figure 7: Input Force Required for First Half of Travel

Figure 8: Input Force Required for Second Half of Travel

Table 3 highlights the average and maximum forces applied during each of the tests. Also, the average torque was obtained by multiplying the average force by the radius of the shaft being rotated.

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Table 3: Average, Maximum Forces. Average Torque

Left to Center Center to Right

Average Force (N) 1.26 10.13

Maximum Force (N) 4.54 30.9

Average Torque (Nm) 0.00499 0.04019

The following tables show the results of the frictional forces experienced on the assembly from

different input forces on the shaft based on the modeled equations. After measuring the input torque on the shaft, the normal force between the nut and the plastic plate can be calculated using Equation 2.7. Once N2 is found, N1 can be calculated from Equation 2.5. Now, the frictional forces can be calculated directly, using published µ values between the appropriate materials. If the recorded input force did not turn the rod, then the µ value used should be a static value. Once the shaft beings to turn, µk should be used because the shaft is in motion.

Table 4: Relevant Friction Coefficients and Angle of Threads

(plastic on plastic) 

(angle of threads) 

(plastic on steel) 

µ2  Θ  µ1 0.5  31.6  0.25 

Table 5: Resultant Normal and Frictional Forces Experienced due to Input Forces

Fshaft  N2  N1  Fs1  Fs2 

0  0  0  0  0 0.5  0.063  0.945  0.236  0.031 5  0.632  9.454  2.363  0.316 10  1.264  18.908  4.727  0.632 15  1.896  28.362  7.090  0.948 20  2.529  37.816  9.454  1.264 30  3.793  56.724  14.18  1.896 

From Equation 2.7 it can be seen that . As a result this relationship can be plotted to determine the relative force required to move the horizontal assembly.

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Figure 9: The relationship between the thread angle and the input force.

(Note that the force on the vertical axis is a relative force and does not represent actual values.) In the application a small input force is undesirable as it may cause problems with the accuracy of the template position. If the input force is too large, the handle might break or the user might have difficulty adjusting the template. In order to avoid this, the angle used would ideally lie between 30° and 60°. 4.0 Uncertainty Analysis The normal force between the nut and the bracket is not directly measurable in this experiment, and therefore as a derived number it will have an uncertainty associated with it. This uncertainty will be related to the uncertainty of the other variables within its Equation of description shown below.

(4.1) In this equation, N2 is the normal force between the nut and the bracket, µs is the coefficient of static friction between the two plastic materials of the nut and bracket, θ is the Acme thread pitch angle, and Fshaft is the measured input force required to overcome static friction. The uncertainties associated with these variables are found from literature review and observation in the experiment. Because of the complication of finding the uncertainty in θ and the unlikelihood of it having an impact on the overall uncertainty, the uncertainty of θ (ωθ) is assumed to be 0. The value found for µs between two plastic surfaces is 0.5, which because of significant digits has an inherent uncertainty of ±0.05 or 10%. The input force Fshaft is measured from the experimental procedure, and its uncertainty is related to the uncertainty in the force gauge, which is likely to be very small. The uncertainty in the tangential angle between the string and the shaft will be measured with a level or protractor and will lead to an assumed uncertainty in Fshaft of ±3%. Assuming a 1.26 N Fshaft, this would be an uncertainty of ±0.04 N. The overall uncertainty in N2 (ωN2) is derived below.

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(4.2) N

(4.3)

(4.4) Using the values stated previously, the normal force would be 0.118 ± 0.031 N, which is an uncertainty of 26.2%. This uncertainty may be attributed to the inability to directly measure the normal force between the nut and the bracket, and inaccuracies in measurement of the input force required to turn the shaft. This uncertainty analysis was performed for the average force required to turn the shaft during the preliminary and main experiments.

Table 6: Forces and Uncertainty

   (±3%)    Normal Force    

Center to Left  1.26 N  .038 N  .118 N  .031 N 

Center to Right  10.13 N  .304 N  .952 N  .250 N 

5.0 Conclusion From the first experiment it was found that the machinable nut threads through the Acme rod very easily when the two parts are the only two in contact. This showed that the threads were made correctly and that the assembly was acceptable to continue with machining and assembling. In experiment 2 it was found that jig operates as expected and doesn’t exceed the torque that can be applied by the hand. The repetitive use of the handle is not a problem because the adjustment will be made only a few times a day. The Torque required to operate the x-adjustment on the jig varies greatly. This problem is likely due to clearance between the bracket and the slots along the 16” adjustability because it had already been proven that the nut and Acme rod experienced little friction when in motion. The bracket slots on the right half of the jig needs to be filed down so that it slides more easily through the plastic. Without this, the high forces would continue to be found because as table 4 shows, frictional force experienced is increases as the input force increases during regular use. The use of lubricants is not necessary other than WD-40 or a similar lubricant to prevent corrosion. Other lubricants types would be disadvantageous because they could seep out of the assembly onto the worker

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or products. The customer will be advised to occasionally open the assembly to spray WD-40 or a similar lubricant on the Acme shaft. 6.0 Bibliography [1] Tipler and Mosca, 2004. [2] Elert, 2005. [3] Roymech, 2008. [4] Co-efficient of Friction of Dotmar Engineering Thermoplastics, 2009. [5] http://msis.jsc.nasa.gov/sections/section04.htm Who did what: Steven: Background, Uncertainty Analysis, Results, Bibliography, Participation in Experiment, Manufacturing of Prototype Joe: Specific Aims, Procedure, Conclusion, Participation in Experiment, Manufacturing of Prototype Kevin: Significance, Results, Conclusion, Participation in Experiment, Manufacturing of Prototype, and the Who did what section Ryan: Procedure, Participation in Experiment, Uncertainty Analysis, Aided in Manufacturing of Prototype Rob: Abstract, Introduction, Table of Contents, Formatting, Built the Mockup, Aided in Manufacturing of Prototype

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Appendix C: FEA Analysis

1. Overview

a. Description of Need and Solution

The current method to setup the labeling jig is inefficient and time consuming for a blind mail room employee. The aim of this device is to reduce the setup time and effort needed. The newly designed device will make the template easier to adjust with regards to different types and sizes of mail. The device will allow the customer to become more productive and enable other blind people to label mail in an easier manner.

The device takes a whole new approach to the current method of setting up the template. The new frame is composed of 1 ¼” steel square tubing with one face removed. The actual labeling surface is plastic. There are two raised surfaces on the bottom and on the left to allow for a 90 degree angle in the lower left hand corner. This raised surface will allow the customer to place the mail in the corner and have a consistent starting point for the labeling process. There are two methods of adjusting the labeling template. The method for adjusting the template in the X direction (left and right) is based on an Acme threaded rod principle. A machined Acme rod sits in two bushing seats in order to rotate smoothly. Attached to the threaded rod is a machined Acme nut which is attached to a custom machined aluminum bracket. The aluminum bracket fits between two machined slots in the plastic labeling surface to allow the bracket to move from left to right as the treaded rod is rotated. The adjustment in the Y direction (up and down) is made possible by “T” shaped labeling bracket. The bracket is machined out of aluminum stock. The “T” shaped piece was machined to fit within the aluminum bracket of the X direction adjustment and is able to slide up and down in the Y direction. The labeling bracket is held in place by a small aluminum plate and two thumbscrews to provide a tight hold. Attached to the end of the labeling bracket is a 3 inch wide piece of thin plastic to allow the customer to feel where the labels are to be placed. The thin plastic template is attached to the sliding bar with locking push fasteners and adhesive. Per request of the customer two legs were added to the design to allow the device to rest at a slight angle allowing for easier labeling. All pieces (minus plastic template) are held in place with either screws or nuts and bolts.

b. Figure of Assembly

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Figure 1.1: Jig

c. Figure of Exploded Assesembly

Figure 1.2: Parts Explosion

d. Parts List

See section 2.a

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2. Solid Modeling

a. The Descriptions of each part will be given in relation to their position to the hierarchy tree shown below in Figure 2

Figure 2.1: Hierarchy Tree

The bore bearings, screws, nuts, bolts and washers were all pieces bought from either Lowe’s or McMaster.com and thus will not be detailed below. X Subassembly Bearing Seat 1

This part connects to the steel tubing with two #4-40 tapped holes. The part also connects to the plastic with two #10-24 tapped holes. This part holds a bushing that allows the frictionless rotation of the Acme screw. Bearing Seat 2

This part connects to the steel tubing and plastic plate in the same was as Bearing Seat 1. This part also holds the other bushing, but in addition has a thru drilled hole so that the Acme screw can be turned by a handle.

Acme Rod

This part transfers the rotational torque of the hand, into a translational force on the Acme Nut. The part is turned down on the ends with a lathe to fit into the bushings.

18” Steel Tube

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This part is welded to the other members in the steel frame of the assembly. This tube protects the Acme screw, nut, and bushings from the environment. The tube has four countersunk holes to connect to the two bearing seats on each end. Y Subassembly Plastic Template

The plastic template is the thing plastic plate connected to the end of the T-Slider. Its purpose is to bend down towards the labeling plate when force is applied to it by the user. This allows the visually impaired user to locate the correct labeling position.

There were no required associative parameters required with this part, as it was just a simple thin rectangle. The chamfers, which are the child features of the part, were each defined together as 1/8’’.

T-Sliders

The T-slider part is the part that provides the adjustment in the Y-direction. It can be positioned at any extension and then can be fastened to the bracket. The template also connects to the end of it to reach the labeling area.

A variable used in this part was setting the width of protrusion 2 (the crossing of the “T”) to be equal to twice the width of protrusion 1 (the vertical part of the “T”).

Clamp The clamp’s purpose is to act as a fastener on top of the bracket. It fixes the T-slider in place at whatever setting is needed for the current label position. It is a very simple part, and needed no special associative parameters.

Bracket

The bracket is significant in our design, as it is the connection between the machinable nut which is traveling down the Acme rod and the T-slider which actually helps apply the labels. The associate parameters used were horizontal relationships for each set of holes to ensure that they remain aligned with each other.

Also, the two sets of countersunk holes on the bracket’s legs were given geometric constraints. These were constrained to the bottom of the legs because no matter how the bracket was changed, those holes needed to stay the same distance from the bottom so they would remain flush with the corresponding holes on the machinable nut. Machineable Nut

The machinable nut is a threaded nut made to fit on our Acme rod. It carries the Y-Assembly in the X-direction because its rotation is constrained, forcing it to travel down the Acme rod when it is turned. It is the connection piece between the X-Assembly and the Y-Assembly.

The two holes that travel all the way through the top half of the part were given a horizontal relationship to ensure that they are equally spaced in relation to the part. A geometric constraint on those same holes forced them to stay one and a half diameters from the side edge of the part.

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Plate Assembly Label Plate The label plate is the base of our design. It is the place the user places the mail to be labeled. It is not however the core of the design, it is attached the tubing frame which was welded together first. Horizontal Corner Guide This is the guide running along the bottom of the plate. The mail is brought next to this piece to center it before labeling. The Y directional assembly moves directly above this piece. Vertical Corner Guide This serves the save purpose as the horizontal corner guide however it runs the length of the left side of the plate. Legs The legs were added at the request of the user after the initial mock-up was presented to him. He requested some way to angle the plate towards him and this solution was developed. The legs are retractable to give the user options. They are attached with two bolts, one going through the leg, the other being used as a stop to keep the legs in place when in use. The bolts, nuts, and washers below the plate in the hierarchy are all used in the leg assembly. Long Side Tubes These tubes serve as part of the frame. Initially they stood alone but once warping issues with the plate were identified they were paired with the middle tube and welded together. These tubes serve as the frame of the jig. Middle Tube This tube is the middle part of the frame structure. The screws listed below this tube serve to attach the tubes to the plate. The bolts and washers serve to attach the plate to the X directional assembly.

3. Assembly Modeling

a. Hiearchy- see section 2.a

b. Description of associatively across models

Steel Tubes, Bearing Seats and Legs As the steel tube width and depth were closely related in dimensions, relationships could be applied to aid in model updating. The width and depth of the bearing seats were dependent on the width and depth of the steel tube in the X-assembly. The width of the leg was also dependent on this variable in the Y-assembly. Screws, Nuts, Bolts and Washers Associatively among screws nuts is mostly restricted to the holes. The countersinks and hole diameters of screw holes are associated with their respective screw diameters. The holes for the bolts as well as their respective washers are associated with the bolt diameter.

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X Assembly The associatively in the X assembly was similar to that of a screw-screw hole association as most of the parts fit into each other axially. This is true for the rod, bearings, screw and nut. Y Assembly The Y assembly pieces also fit to each other similarly. Bracket dimensions were associated with Nut dimensions. Clamp width was associated with bracket width. T-slider width was associated with bracket slot width. Template screw holes were associated with t-slider screw holes and bracket screw holes were associated with nut screw holes.

c. Description of Tolerances and Clearances

There are serious tolerance issues as the part contains small pieces that must move through each other. In the plate subassembly, the legs must fit into the hollow tubes. They were designed to have significant clearance in the width direction. A depiction of this is found below in Figure 3.1

Figure 3.1: Leg Clearance

In the X subassembly the parts are intended to fit within each other exactly save for the

nut which is supposed to have free motion with in the tube. Clearance was intentionally designed in this case to give the part free motion.

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Figure 3.2: Nut Clearance

In the Y assembly the template must slide directly over the horizontal guide. It is also

designed to extend 5 inches and retract so that there is no lip over the horizontal guide.

Figure 3.3: Template Clearance

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When the Y directional assembly was initial created, it was found that some of dimensioning was off. This was apparent as there was a 1/8 inch overlap between the template and the horizontal guide. Using the measure tools in the solid edge assembly program we were able to assess and fix this problem by changing the size of the bracket.

Failure Mode 1: Failure of Template 1. Methods

a. Geometry Shown as the orange piece in Figure 4.1.1, the template is a rectangular

piece measuring one inch in length by four inches in width. It is attached only to the t-slider above it and therefore will be constrained only at this point. The template has an un-deflected offset of 0.25 inches from the white plate beneath it. The piece can be cut in half using symmetry to reduce the size of the model.

Figure 4.1.1: Y-Adjust Assembly

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b. Meshing A variety of meshing techniques were used and recorded. The initial 14

meshes focused on brick elements. However, after learning about plate elements and the potential upside to using midplane nodes the further meshes were ran as a plate analysis. The following 10 analyses were performed using plate analysis and linear stress analysis. This analysis appeared never to converge. The last trail, as shown in Table 4.1.1, used over 100000 DOF and was over 6% different in Von Mises stress from the previous trail.

Table 4.1.1: Mesh Results for Template, Trails 24-26

The following meshes were done using nonlinear analysis. Only four

meshes were needed to ensure convergence as seen in Table 4.1.2. The Von Mises stress converged around 31ksi. 3 Refinement points were used around the bottom right corner which is where the highest stresses were present as seen in Figure 4.1.2 below.

Table 4.1.2: Meshes 27-30

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Figure 4.1.2: Stress Concentration Areas

c. Materials The material used for this part was polystyrene. The properties were manually imported into Algor. They were developed from information at 3d-cam.com [1].

Figure 4.1.3: Imported Material Properties

d. Loads and constraints

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For analysis the Piece was cut in half and then constrained as shown below in Figure 4.1.4. Here the right side was constrained in the Tx direction as in reality the other half of the plate occupies this space. The cutout in the bottom right side represents the area which the template is constrained to the t-slider. This line was pinned (constrained in Tx, Ty, Tz) to allow for rotation but not translation.

A force was added along the top of the plate to represent the force exerted by the user. This force was added as a nodal force and can be seen in blue Figure 4.1.4

Figure 4.1.4: Forces and Constraints

The actual force exerted was developed using Algor. As a 0.25

displacement would correspond to the maximum force the user could exert before the force was translated into plate, the force corresponding to this displacement would be used for analysis. It was found that a 6 pound (3 pounds to the half plate model) force resulted in a displacement slightly greater than 0.25 inches. For trials 29 and 30 the resultant displacement from a 6 pound force was 0.255 and 0.254 inches.

2. Results a. Overview

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Figure 4.1.5: FEA results, Trial 30

The plastic does not meet expectations. As the flexural modulus is around

15ksi, the piece enters plastic deformation during use. Although it does not snap, plastic deformation is undesirable as the piece will likely have a permanent bend in it. This was confirmed with real life testing. 5 pounds of pressure not only deflected the piece 0.25 inches, but also visible plastic deformation occurred.

b. Convergence justification The meshes converge on about 31ksi as shown in Table 4.1.2. Sufficient

meshes were and DOF were used to ensure an accurate result. Furthermore independent real life testing verified the deflection results thus giving more merit to the remaining results.

c. Strength The estimated Von Mises stress was around 31ksi. This was essentially

double the force the plastic is able to resist. A graphic representation of this can be found in Figure 4.1.5.

d. Deflection Deflection was recorded in each trail as it was needed to calculate what force

should be applied. A 0.25 inch deflection was required to ensure the model was an accurate representation of actual use. The last trials resulted in deflections very close to this number.

Failure Mode 2: T-slider Failure

1. Methods

a. Geometry

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As the part converged easily symmetry was not needed to reduce the model size.

b. Meshing

The ideal element length I found when meshing my geometry was .03’’. At that size element, it was a fine mesh that still had no trouble finishing the analysis. To ensure extra accuracy, I added a refinement point (of Radius = .25’, and Mesh Size= .01’’) near the point of maximum stress. After meshing with a .03’’ element size with the refinement point, there were 51,883 nodes and 155,649 DOF’s. This was nearly triple the nodes of a mesh with .03’’ element length and no refinement point.

c. Materials

The material used was Aluminum 6061 T-6 with the following properties:

1. Yield Strength = 40 ksi

2. Ultimate Tensile Strength = 45 ksi

3. Poisson’s Ratio = 0.33

d. Loads and Constraints

The load being applied was to simulate Bob leaning the weight of his arms (10 lb) of force onto the extreme end of the T-slider at the 100% extended (worst case) position A surface force of 10lb in the –Z direction was applied to the surface on the end of the T-slider (the cross of the “T”)

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Figure 4.2.1: Loads and Constraints Details

The first constraint was to fully constrain completely around the T-slider near its base to simulate it being fixed in the bracket, and fastened down by the clamp. I fully constrained because at this location, this T-slider should not be able to move in any direction. The second constraint was applied to the extra surface added to the bottom of the T-slider face. This simulated the bonded contact between the T-slider and the plastic rail it will be resting upon. This was applied about 1/3 of the distance from the base of the T-slider

2. Results

a. Overview

The results of the stress can be seen in Figure 4.2.2. The maximum stress indicated in this picture is 10.5ksi which is one fourth of the yield strength. This indicates that the part could stand up to the force not only once but also for cyclical loading. It would not fatigue because the maximum force is less than 40% of the yield strength.

Figure 4.2.2: FEA Stress Results and Max Stress Location

b. Convergence Justification

A summary of the meshes can be found below. Once the results began converging without refinement points, refinement points were added in test five in an attempt to achieve more accurate results.

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Table 4.2.1: Mesh Convergence for T-Slider

Abs. Mesh Size (in.)

% Difference (Stress) Refinement?

Test 1 0.1 - no

Test 2 0.05 9.20 no

Test 3 0.04 6.94 no

Test 4 0.03 2.55 no

Test 5 0.03 2.87 yes

c. Strength

A summary of the resulting stresses for each trail can be found below. The stresses appear to have converged on around 10.5ksi which is significantly lower than the yield strength. The stress as a percentage of yield strength can be found in the adjacent column.

Table 4.2.2: Stress Resultants for T-Slider Trails

Abs. Mesh Size (in.)

Von Mises (psi)

% Of Yield Strength

Test 1 0.1 8410.5 21.03 Test 2 0.05 9263 23.16 Test 3 0.04 9954 24.88

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Test 4 0.03 10215 25.54 Test 5 0.03 10517 26.29

d. Deflection

The following is a summary of the deflection results for each trail. Deflection here was less than 10% of the deflection found in the template (0.25inches) and therefore is not cause for concern.

Table 4.2.3: Displacement Results for T-Slider Trails

Abs. Mesh Size (in.)

Displacement (in.)

Test 1 0.1 0.0207 Test 2 0.05 0.021 Test 3 0.04 0.022 Test 4 0.03 0.0269 Test 5 0.03 0.0213

Failure Mode 3: Bracket Failure

1. Methods

a. Geometry

The top piece is shown below. It was machined out of a 1in square of aluminum bar stock. The two pin holes in the top are used to secure a plate the keeps the T-slider from sliding. The T-slider, when allowed to move, moves between the top two posts. The two posts are of different height which allows the clamping action. There are four countersunk holes along the bottom of the part. These are used to secure the bracket to the machineable nut. The machineable nut fit between the bottom faces

b. Meshing

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Absolute mesh sizes were used from .125 in to .015 in. A finer mesh was used to ensure convergence as well as making sure the aspect ratio was less than 25. Symmetry was not used for this part given the complexity of the part. The mesh size and number of nodes are listed below in Table 4.3.1.

Table 4.3.1: Nodal Results for Bracket Analysis Trails

Mesh Size Nodes

0.125 in 1185 0.1 in 1821 0.05 in 5425 0.025 in 31158 0.02 in 59644 0.019 in 69659 0.017 in 92624 0.015 in 133787

c. Materials

The Aluminum 6063 T6 material properties were used from Algor’s part library. The yield strength is 31 ksi and the fatigue strength is 10 ksi.

d. Loads and Constraints

In order to simulate a direct 26lb downward force on the T-slider, a total of 79lb upward was applied to the two screw holes on the top of the part. In order properly constrain the part, many different areas needed to be specially constrained. The countersink holes were pinned because they would be screwed into the machineable nut. The inside of the bottom faces were constrained in the y-direction because the faces would be in contact with those of the machineable nut. Next, the flat tops of the part were constrained in the z-direction because they would be in contact with the plate. Also the inside of the walls, where the T-slider would go, were constrained in the x-direction.

2. Results

a. Overview

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Figure 4.3.1: Bracket Stresses

The result as shown in Figure 4.3.1 is what was expected as the screw holes are experiencing all of the force.

b. Convergence Justification

Table 4.3.1: Mesh Summary for Bracket Analysis Mesh Size

Max Aspect Ratio

Max Stress lb/in2

Max Strain in/in

Deflection (X10-5)in

.125 in 6.14 1376 1.83E-04 2.48 .1 in 14.17 1724 2.29E-04 2.51 .05 in 10 2156 2.87E-04 2.75

0.025 in 4.09 2761 3.68E-04 2.91 0.02 in 4.07 2804 3.73E-04 2.96 0.019 in 3.12 2880 3.83E-04 2.96 0.017 in 3.22 2934 3.91E-04 2.98 0.015 in 3 3055 4.06E-04 2.99

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As seen from the above table above (Table 4.3.1), the values converge

around 3ksi. As the goal of the analysis was to determine if the designed part would fail in our application, it can be seen that the part will not fail since the maximum values for both the stress and the deflection are not close to the critical values of yield strength. Also for each of the runs shown above, the aspect ratios are acceptable.

c. Strength Justification

Since the yield strength is 31 ksi and the fatigue strength is 10 ksi, and the maximum stress experienced was ~3 ksi, the part is not likely to fail. The stresses reported above are Von Misses stresses. The maximum stress location can be seen below in Figure 4.3.2

Figure 4.3.2: Maximum Stress Concentration for Bracket

d. Displacement

Also note that the value for deflection converges to ~3X10-5 in. This is small enough so that it will not interfere with the sliding of the T-slider or the bracket itself. The direction of the dislocation motion can be seen below in Figure 4.3.3

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Figure 4.3.3: Maximum Displacement Location of Bracket (Scale 5)

Failure Mode 4: Failure of T-slider Clamp 1. Methods

a. Geometry

The clamp is a rectangular piece of aluminum of dimensions 1”x .5” x .25”. The clamp has two drilled holes of diameter .125”

b. Meshing

The table below shows the mesh size, number of nodes, and the maximum aspect ratio for several mesh sizes. Each mesh size is half of the previous mesh.

Table 4.4.1: Mesh Summary

Mesh Size

Aspect ratio Nodes

0.16 12.08 143 0.08 4.07 318 0.04 3.39 983 0.02 1.98 5,211 0.01 1.44 33,819 0.005 1.54 247,595

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c. Materials

The clamp is made from 6061-T6 aluminum. The yield strength of 6061-T6 Al is 40,000 psi. (1)

d. Loads and Constraints

The worst case scenario for the clamp is a 79lb force. Figure 4.4.1 below shows a 39.5lb force upward at the contact between the clamp and the T-Slider. Symmetry is used in the x-z plane. The holes are constrained in the x and y directions, and the top edge of the holes is constrained in the z-direction. The faces cut for symmetry are constrained in the y direction. The left bottom side of the part is constrained in the z direction because it makes contact with the bracket that it is bolted to, but the bottom right side does not.

Figure 4.4.1 Mesh, Forces, and Constraints on Clamp

2. Results

a. Overview

Figure 4.4.2 below shows the Von-Misses stress results. The highest concentration of stress is at the top of the right hole, where it will be held down by a bolt, this makes sense because the maximum stress occurs at the points that are constraining the force.

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Figure 4.4.2: Von-Misses Stress in Clamp

b. Convergence

The maximum stresses did not converge, but the deflection does. At over 200,000 nodes, the maximum stress is above the yield stress. The nodes that do not converge with the maximum stress are considered artifacts of the analysis. The addition of a fillet on the holes would eliminate these artifacts.

c. Strength Justification

Table 4.4.2 below shows the results of the analysis. The maximum stress reported is only an artifact. The actual maximum stress is below the 40,000psi yield stress of the material.

Table 4.4.2: FEA Results

Mesh Size

Max Stress (lbf/in^2) Aspect ratio Strain (in/in) Nodes Deflection (in)

0.08 4426 4.07 0.000589 318 0.00011800.04 5962 3.39 0.000793 983 0.00015800.02 11765 1.98 0.00156 5,211 0.00017000.01 22698 1.44 0.00302 33,819 0.0001790

0.005 44673 1.54 0.00594 247,595 0.0001830

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d. Deflection

The maximum deflection detected was less that 1/1000 of an inch and will pose no failure scenario within the assembly.

Failure Mode 5: Failure of Acme Nut

1. Methods a. Geometry

The machineable nut is nut made out of Polyethylene Terephthalate (PET). It has an internal Acme thread that matches our Acme rod. When ordered from the manufacturer it comes as a round nut that is able to be machined. The part was machined to allow the bracket to be mounted in a secure fashion with four #4-40 tapped holes.

b. Meshing

Absolute mesh sizes were used ranging from .125 in to .017 in. A finer mesh was used to ensure convergence as well as making sure the aspect ratio was less than 25. Symmetry was used and the part was cut in half. The mesh size and number of nodes are listed below in Figure 4.5.1.

Figure 4.5.1: Nodal Results for Nut Mesh Trails

Mesh Size (in) Nodes

.125 in 537 .1 in 679 .05 in 3093

0.025 in 19009 0.02 in 36438 0.019 in 41985 0.017 in 57324

c. Materials

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The material properties for PET were used from Matweb [2] to analyze the part. The lowest value of the yield strength of PET was 6.820 ksi.

d. Loads and constraints

Symmetry was used for this part and thus the nut was constrained in a number of ways. The area that the rod passes through was constrained in the y- and z-directions. Next the vertical pillar faces were constrained in the y-direction because these faces come in contact with the inside faces of the bracket. Next, the back side was constrained in the x-direction because this is where the part was cut for symmetry. An equivalent load of 79lb upward force was applied to the part, however because the part was cut in half a load of 39.5 lb was applied to the hole.

2. Results

a. Overview

Figure 4.5.1: Stress Results for Acme Nut

Figure 4.5.1 shows the stress results. The maximum stress in this trail was 1010, however the trail was not recorded. The stress concentrations were found in the expected areas as the largest stress came from the screw holes.

b. Convergence Justification

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Table 4.5.2: Mesh Summary for Acme Nut Analysis

Mesh Size

Max Aspect Ratio

Max Stress lb/in2

Max Strain in/in

Deflection (X10-5)in

.125 in 4.96 492 0.0057 5.85 .1 in 6.01 753 0.0028 3.19 .05 in 14.7 698 0.0026 3.61

0.025 in 1.98 918 0.0034 4.06 0.02 in 2.19 996 0.0038 4.13 0.019 in 2.40 1011 0.0038 4.13 0.017 in 1.63 1002 0.0038 4.14

As seen from Table 4.5.2, the values appear to have converged. Also for each of the runs shown above, the aspect ratios are acceptable and well below the 25 limit.

c. Strength

The maximum stresses that the part would receive, according to the Algor analysis, is around 1 ksi Von Misses. This is well below the 6.82 ksi yield strength from MATWEB and thus not expected to yield or fatigue in normal use. The maximum stress location is shown below in Figure 4.5.2.

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Figure 4.5.2: Maximum Stress Location Acme Nut

d. Deflection

Deflection is not a major concern mostly due to the fact that the sides of the machineable nut are ~.25 in from the side of the square tube and thus the deflection will not interfere with its motion. Furthermore the displacement found was less than one twenty thousandths of an inch (<0.0005in). The location of the maximum displacement is shown below in Figure 4.5.3.

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Figure 4.5.3: Maximum Displacement Acme Nut

Failure Mode 6: Bending of Acme Rod 1. Methods

a. Geometry

The rod was first cut in half from end to end to take advantage of symmetry. The ends were fixed to simulate stationary bushings that in a direct upward application will see no rotation. The symmetrically cut side of the part was constrained in the y-plane.

Figure 4.6.1: Rod Forces and Constraints

b. Meshing

The analysis revealed a maximum von mises stress of approximately 25 ksi. Convergence happens as the refinement points are narrowed down to a goal element edge length of 0.009”. The stress only increased about 300psi with an increase of over 7,000 degrees of freedom. The overall element size was 0.05” which was adequate for the long uniform shaft.

Table 4.6.1: Rod Meshes Rod Finite Element Analysis for a 26 lbf upward on the shaft

mesh size refinement nodes elements DOF

max von mises max deflection

0.05 no 27500 43435 82500 11787.34 0.00740.025 no 158886 216009 476658 15417.02 0.0074

Refinement at 4 points of interest with an effective radius of .075" 0.05 yes 0.0125 30058 42951 90174 24864.20 0.00740.05 yes 0.0090 32453 44635 97359 25176.83 0.0074

c. Materials

Table 4.6.1: Properties of 1018 Steel Ultimate Tensile Strength, psi 65,300 Yield Strength, psi 45,000

 

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Fatigue Strength, psi (40% UTS) 26,120 Elongation 15.0% Rockwell Hardness B71

d. Loads and Constraints

The force applied to the rod in reality is 26 lb-f in the upward Z-direction due to a moment caused by the labeling arm as the customer applies a 6 pound labeling force. Only half of the part was being analyzed, therefore, a 13 lb-f was applied to a flat cut-out on the center of the rod. A cut-out was made so that an equal load could be applied easily for each new mesh created. This was previously illustrated in Figure 4.6.1

2. Results a. Overview

As seen in Figures 4.6.2 and 4.6.3, there were no stress sensitive areas besides at both ends near the step down of the rod. Stress was similar at the top and bottom.

Figure 4.6.2: Von Mises of entire Rod

 

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Figure 4.6.3: Maximum Stress location

The maximum stress from the analysis of 25ksi is within a safety factor of 1.8 compared to the yield strength of the steel. With an approximate fatigue strength of 26ksi there could be a cause for concern for fatigue failure, but not after many years. The customer will not reach the number of cycles needed to injure the part.

b. Convergence Justification

Using the numbers from Table 4.6.1 it can be seen that there was only a 1.2% difference between the trials leading to the conclusion that the stresses have converged on around 25ksi.

c. Strength

As previously mentioned in section 2.1 of this section the strength meets the requirements with a 1.8 factor of safety.

d. Deflection

The displacement remained the same for every analysis at .0074” which will cause no harmful bending of the middle of the rod. Figures 4.6.4 shows the location for the maximum displacement.

 

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Figure 4.6.4: Displacement of entire rod

Figure 4.6.5 illustrates the difficulties associated with Algor analysis. This

picture uses a helpful rainbow spectrum.

Figure 4.6.5: The Pitfalls of Algor

WHOA!!! 

 

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Appendix D: Executive Summary/NISH Report

BLIND-ASSIST LABELING TEMPLATE Kevin Hackett, Darren Quelette, Ryan Risdon, Steven Rogers,

Dominic Rosselli, Rob Sampson, and Joe Schultheis Ohio University

ABSTRACT

As part of the senior design experience at Ohio University, the members of ‘Team Better Way’ designed a template to aid in positioning and placing labels on mass mailings for a blind mailroom employee. The objective was to make a new template that can be set up much more quickly than his previous device by simplifying and improving the process. By using the new template, our customer can set up his labeling jig in the correct position on the first try in one-third the time it took to set up the previous jig. In addition, because of the new simplified process, the labeling template may be used by other blind or disabled employees that may have not been able to do this work previously. BACKGROUND Our NISH affiliated nonprofit agency (NPA) is SW Resources in Parkersburg, West Virginia. Their Mail Plus division provides billing, mailing, and direct imprinting services. They currently process over one million pieces annually[1]. Our customer works in this mailroom, and his primary job is to place address labels on bulk mailings. He is completely vision impaired, so he uses a special jig to help him locate the correct position of the labels on each of the mailings. His original setup used a small template with hand-cut cardboard pieces that he set up on his own. STATEMENT OF PROBLEM The previous labeling jig setup process was difficult even for someone without a disability, and under normal circumstances our customer would take multiple tries to get the cardboard in the correct position to accurately place labels on the mail. The way the customer set up the original jig took multiple steps, as follows:

1) Locate a pre-labeled piece of mail in the square corner of the jig. 2) Open envelope of about 20 pre-cut cardboard pieces and pour onto table. 3) Sort through the cardboard pieces until a possible good fit is found. 4) Line up the cardboard on the jig.

a. Repeat step 3 until the correct fit is found. b. If there is no good fit for the piece of mail, use scissors to cut a new piece.

5) Clamp down the cardboard on the jig with two large paper clips. 6) Check the position with an unlabeled piece of mail and compare.

Our individual customer was the only one in the mailroom who was able to use his previous setup. Over time he became familiar with his own system, but even with that familiarity it took a considerable amount of time to set up for labeling large lots of mail. RATIONALE

 

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There was a significant opportunity presented by this problem to improve the setup of the labeling process. The customer needed a sturdier and simpler device that can be set up solely by tactile cues. After doing market research, we found no similar devices for this application. By providing the customer with an improved device, our design team would be able to reduce the customer’s frustration with his previous jig by reducing the time it takes to set up. We could also open up this process to other disabled employees who were unfamiliar with our customer’s original process. The objective was not to improve the productivity of the customer’s actual labeling, but through ergonomic considerations taken into the design an improvement in productivity is possible. DESIGN The idea behind this design is to improve on the following aspects of the current set up:

- Number of steps - Ease of steps - Likelihood of error The design allows a blind

user to set up for labeling in three simple steps. First, the user takes a pre-labeled piece of mail and locates it in the square corner. Keeping his hand on the label, he then adjusts the knob on the right side until the template is in the correct horizontal position. To adjust in the direction away from the user he loosens the thumb screw on the slider, moves the slider, and then retightens the thumb screw when it is in the correct position. At this point the user is ready to place labels on mass mailings by using the thin plastic tab attached to the end of the slider as a position guide. The plastic tab is the same width as the labels, and it flexes down to the working area when it is pressed down by the user. Detailed Design Description The working space in the design is 16 inches wide by 12 inches out from the user in order to accommodate different sizes of mail. The user can adjust in the full range of the horizontal direction and half of the range in the vertical. Only half of the vertical range is needed because the mail can be turned 180° and will never be greater than 12 inches on the shortest side. The horizontal motion is achieved with an Acme-threaded rod and nut system to which is attached the vertical adjustment. The vertical adjustment is a plastic T-shaped slider that is clamped in an aluminum bracket with thumbscrews. The plastic tab is permanently attached to the end of the T-slider using small machine screws. It is the main interface between the user and the mechanism, as he uses its position to locate the exact position of the label on each piece of mail. The user can set its position once and go through an entire lot of mailings of the same size. The rear of the template is elevated with a leg in each of the two corners to provide a more ergonomic workspace that is tilted up towards the user.

Figure 1: Final Design Rendering & Steps for Setup

 

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We chose materials that balanced cost with sturdiness. The working space is made of plastic, and it is reinforced with a welded steel frame backing. The Acme-threaded rod is steel, and the polymeric Acme-threaded nut is encased within the frame, which not only helps provide rigidity but also prevents the user from being pinched by the threads and the traveling nut during adjustment. There are no moving parts while the template is in use, which makes the device very safe. The total cost of our prototype was $273.81, which includes extra materials and testing supplies.

Function The number of steps to set up the new

design is fewer than the previous design. Our template can be used to accurately set up for a mailing in three steps (see Figure 2 at left), where the previous template required at least five steps that may need to be repeated several times to achieve the correct positioning. In testing, the new template was three times faster to set up than the old template. The steps are much simpler than before, and may be performed by someone other than the original customer for whom this was built. Our original customer was very high- functioning and was able to use scissors to cut pieces of cardboard to the correct size for positioning on the old template. He could also sort through about 20 pre-cut cardboard pieces to find the correct size. With the new template, a blind user who is unfamiliar with our original customer’s setup would be able to quickly learn the three steps to position it correctly. The new design is also much more sturdy and stable than the previous design. It can be set once and reliably maintain its position throughout an entire lot of labels, which could reduce error by the user. By tilting the workspace toward the user, our customer has a more ergonomic jig that may help improve efficiency.

DEVELOPMENT The design was developed and improved with the advice and counsel of the customer. The design went through several stages. First we identified the initial customer specifications including the desired shape, size, adjustability, and function of the jig. From this information we created an initial conceptual design and delivered a wooden mockup to the

Step 1: Locate pre-labeled mail in raised corner

Step 2: Adjust horizontally with knob

Step 3: Adjust vertically with thumbscrews Step 4: Add labels to mail

Figure 2: Usage of the Design

 

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customer. The mockup was positively evaluated by the customer with a few improvement suggestions, such as a change in the adjustability. With this and other suggestions, we updated the design and constructed a prototype. After construction and testing by the design team, we delivered the prototype to the customer for a week. He suggested additional improvements and time trials were obtained in meetings with the customer. These changes were added to the final design that has now been delivered to the customer. See Figure 3 below for the progression of our design.

 5. Initial Design

6. Mock-Up

 7. Updated Design

8. Final Prototype

Figure 3: Stages of the design The initial design and mockup were made with a vertical adjustability of 0 to 4 inches from the bottom locating strip in ¼-inch increments. After feedback from the customer, it was determined that the vertical direction needed a sliding rather than an incremental adjustability. To address this design change, we used a clamp to secure the square T-slider as shown in pictures 3 and 4 in Figure 3. We also changed the material of the T-slider from aluminum to plastic to improve its wear properties, and made a second T-slider to account for longer range.

Another issue that was resolved was the design of the plastic tab dimensions and materials. The original plastic tab had a smaller width than the labels being placed on the mail which caused difficulty in the labeling process, and it did not bend the amount desired by the customer. We fabricated a new tab with the correct dimensions and a more flexible material that could be more easily bent to the work surface.

EVALUATION

 

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The effectiveness of the prototype was evaluated based upon a timed setup test by the customer. This was a basic time trial test that compared the setup time of the new device to the customer’s old method. The original device took approximately 100 seconds from the start of setup to apply labels to a piece of test mail. The newly designed device showed a large improvement by reducing the time of setup to 30 seconds. This proved that the new design can be validated as an improvement in the time needed to setup the device. Another improvement that the design addressed was the ease of use. This improvement is defined by the number and complexity of the steps required to operate the device compared to the steps required before the jig was implemented and is shown in Figure 4 below. Not only are there now fewer steps, but also the steps are easier to perform than in the previous process. For example, cutting the cardboard in the old process is much more difficult for a blind person than simply turning the handle to adjust the jig with the new process. Although our focus was to create a labeling device for the blind, people with other disabilities may now also use the jig. Persons with minor mental disabilities will find the new labeling steps from Figure 4 much easier to accomplish than those of the previous method. The previous labeling method requires the ability to sort through slightly differently shaped pieces of cardboard and even possibly the use of scissors and tape, but now people with other limitations or trouble using scissors will be able to do the job more safely and effectively.

Previous Labeling Steps New Labeling Steps 2.) Remove and discard old cardboard and tape 7.) Put example envelope onto jig 8.) Put example envelope onto jig 9.) Cut cardboard to proper size with scissors

2.) Adjust template in horizontal direction

10.) Align cardboard with label and jig 11.) Clamp cardboard down to jig

3.) Adjust template in vertical direction

12.) Begin Labeling 4.) Begin labeling Figure 4: Previous and New Labeling Steps

DISCUSSION & CONCLUSION Overall, our design was received very well by the customer and was successful in greatly improving his setup time for his labeling process. He told us that there is “no comparison” between the old setup and our design, and he is very pleased with what we have delivered to him. The new jig has proven to greatly reduce the amount of time it takes to set up for labeling, and this is based on a test of a person who has done this job for many years. Because of the simplicity of the new device, this job may now be opened up to other disabled employees. Our customer even expressed interest in purchasing an additional jig for another vision impaired mailroom employee who was previously unable to use the customer’s jig. We managed to produce a simple, sturdy, and effective device that exceeds the customer’s requested specifications. We improved the ergonomics of the workspace, and therefore improved the overall satisfaction of the customer with his job. The design is safe and effective, and will continue to be used for years by our customer and others at SW Resources. REFERENCES & ACKNOWLEDGEMENTS

1. SW Resources. Mail Plus Department. 2008. http://www.swresources.com/html/mailplus.html 

 

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Our team would like to thank Dr. Greg Kremer for helping us through the design process, Randy Mulford for helping us in the machine shop, and we would also like to thank our customer Bob and all of the staff at SW Resources.

 

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Ryan Risdon 435 Thomas Alva Dr. Vermilion, OH 44089 Alternative Text Figure 1: Figure one details the steps required to use the jig. Three text boxes appear in the top right corner of the graphic. The boxes use a color coordination system to correspond to arrows showing movement on the jig itself. The first text box reads “Position Mail” and corresponds to an arrow showing how the mail is lined up in the corner of the jig. The second box reads “Turn Knob and Adjust Right/Left” and the two corresponding arrows show both the rotation of the knob and the resulting right/left motion of the template. The third box reads “Loosen Screws to Adjust Up/Back.” The arrows associated with this graphic depict the two thumb screws being turned to loosen the slider, and a third arrow shows the directions in which the template is then free to move. Figure 2: Figure two details the function of the jig by showing three consecutive pictures that each depict a specific set up step. The first graphic shows an envelope being slid into the corner of the jig with directions in a text box that read “Slide mail under labeling template and make flush with 90 degree corner.” The second graphic shows the knob being turned and the template sliding in the right direction. A text box in the upper right corner reads both “Counter Clockwise Translates movement to the right,” and “Clockwise Translates movement to the left.” The third picture is a close up of the template and envelope. Through the use of directional arrows, this graphic shows the perpendicular movement and the loosening of the thumb screws. A text box in the bottom right corner reads “Loosen thumbscrews in order to adjust/switch slider then retighten.” Figure 3: Figure 3 uses four images to show the progression in the design process from the initial design to the final prototype. The first image is a 3-dimensional isometric CAD image of the initial design of jig. The image shows a series of evenly spaced holes at 1/4 inch increments on the T-slider, and it is held in place with a quick release pin through its side. The second image is a photograph of the wooden mock-up that was used to get initial feedback from the customer. The wooden mockup does not show the plate that covers the Acme threaded rod or the legs that were added per request of the customer. The third image is the updated design model. It is an isometric CAD image of the changes made per request of the customer. Notable changes to the design include: the change from a quick release pin to the thumbscrews to hold the T-slider in place, the addition of the legs per customer request, and the addition of the horizontal adjustment knob. The fourth image is a photograph of the final prototype. This image shows all the final adjustments that were made after receiving customer feedback. The final prototype image shows the newly designed plastic T-sliders that were fabricated in order to meet the new customer specifications. Figure 4: Figure consists of text comparing previous and new labeling steps. Refer to figure for full text. Video: The video shows our customer, Bob, setting up the jig in order to apply labels to a test piece of mail. The test piece of mail is an engineering magazine with a standard mail label placed in a random location. Bob begins the setup by adjusting the T-slider in the vertical direction by loosening the thumb screws and moving the T-slider to the appropriate height for

 

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the label. He then tightens the thumbscrews in place to keep the T-slider from moving. Next, he adjusts the horizontal position such that the upper right corner of the T-slider meets the lower left corner of the label. This adjustment is made by turning the handle on the bottom right side of the jig in order to adjust the horizontal position. The customer then uses his sense of touch to make sure that the position of the labeling template is in the correct position to label additional pieces of mail.

 

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Appendix E: Part Drawings

 

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Figure 1: Label Plate Drawing #001

 

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Figure 2: Horizontal Corner Guide Drawing #002

 

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Figure 3: Vertical Corner Guide Drawing #003

 

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Figure 4: 13.25” Steel Tube Drawing #004

 

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Figure 5: 15.5” Steel Tube Drawing #005

Figure 6: 18” Steel Tube Drawing #006

 

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Figure 7: Leg Drawing #007

 

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Figure 8: Acme Rod Drawing #008

 

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Figure 9: Bracket Drawing #009

 

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Figure 10: Bushing Seat1 Drawing #010

 

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Figure 11: Bushing Seat2 Drawing #011

 

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Figure 12: Nut Drawing #012

 

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Figure 13: Clamp Drawing #013

 

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Figure 14: T-Slider Drawing #014

 

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Figure 16: Template Drawing #016

 

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Appendix F: Assembly Drawings 

 Figure 17: Y-Assembly Drawing #017

 

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Figure 18: Entire Jig Assembly Drawing #018

 

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Figure 19: X-Assembly Drawing #019

 

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 Figure 20: Plate Assembly Drawing # 020

 

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Appendix G: Users Manual

Labeling Template Users Manual

By: A Better Way, OU Senior Design Team 3.

4/18/2009

Set up

There is no set up required for operation of the jig. However, if the user desires the jig to be set

at an angle, there are legs on the bottom of the jig on the side furthest from the user. These legs

can be extracted so that a slight usage angle is achieved. To do so, lift the back side of the jig

and manually rotate the legs around so that they are set in their use position at an angle of 7

degrees (See Figure 1). Place the jig back on the table.

Figure 1 Open Position of Legs

Use

Use of the jig involves two separate and distinct operations. The following two sections divide

the use into movement of the template in two directions which will be named the X direction and

the Y direction.

X direction:

X directional movement is accomplished by turning the handle located on the right side

of the jig. Turning the handle clockwise will move the template to the right and turning the

handle counterclockwise will move the template to the left (See Figure 2).

 

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Figure 2 Movement of X Adjustment

Y direction:

Changing the template in the Y direction requires loosening of the thumb screws that

hold the T-slider to the bracket. If these screws are sufficiently loosened, than the T slider can be

adjusted in the Y direction to the desired length (See Figure 3). The jig came with two T sliders

one of length 3 inches and the other of length 5 inches. The T sliders can be interchanged to

achieve any desired length between 0 and 5 inches. Once the T slider is reset into the new

desired position tighten the thumb screws to lock the parts in place.

Figure 3 Y Adjustment

 

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Safety

• When adjusting with the handle, keep all fingers and clothing away from the moving

slider so that nothing is pinched or caught in the device.

• Take care not to pinch fingers on the legs when retracting them from their storage

position.

• Place on a level, dry surface.

Service / Maintenance

To maintain the labeler for continued effective use, it is recommended that the top plate

be removed every 3-6 months for maintenance on the Acme threaded rod. To remove the top

plate, each of the screws connecting the plate to its steel frame must first be removed. Next, the

screws attaching the bushing seats to the plate must be removed. Once all fasteners are removed

from the plate, it can be safely lifted for easy access to the Acme rod. Once the rod is exposed,

the area inside its casing can be blown out to remove dust. Also, if any lubrication is needed it

can be applied along the rod.

It is also recommended the bushings be replaced once every 2 years due to expected

wear. To remove the bushings, follow the removal instructions from above to remove the plate.

Once the plate is removed, the set screw handle must be removed. The final fastener to remove is

 

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on the bottom of the steel frame, attaching the bushing seats to the frame. Once removed, the

bushings seats can be removed and inspected. To remove the bushings from the seats, pliers are

necessary.

WARNING: Do no remove bushings unless they are ready to be replaced. Removal of still

functioning bushings will destroy its functionality.

To reassemble the labeler, all fasteners must be refastened in the following order:

1. Bottom screws of bushing seat OPPOSITE of the handle, connecting seats to frame

2. Feed Acme rod through the other bushing seat, and refasten set screw to end of screw

3. Bottom screws of bushing seat on handle side, connecting seats to frame

4. Top screws connecting bushing seats to plate

5. All remaining fasteners connecting frame and plate together