Cam Notes(Book Groover)

8/3/2019 Cam Notes(Book Groover)

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CAM

MISSING NOTES

BOOK- (M.P Groover)

UNIT-1

- OVER VIEW OF AUTOMATION IN INDUSTRY:

Some elements of the firm's production system are likely to be automated, whereas

others will be operated manually or clerically. f-or our purposes here, automation can be

defined as a technology concerned with the application of mechanical, electronic, and

computer-based systems 10 operate and control production. The automated elements of

the production system can be separated into two categories: (1) automation of the

manufacturing systems in the factory and (2) computerization of the manufacturing

support systems. In modern production systems, the two categories overlap to some

extent because the automated manufacturing systems operating on the factory floor are

themselves often implemented by computer systems and connected to the

computerized manufacturing support systems and management information systemoperating at the plant and enterprise levels. The term computer-integrated

manufacturing issued to indicate this extensive use of computers in production systems.

The two categories of automation are shown in Figure 1.6 as an overlay on Figure 1.1.


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- TYPES OF PRODUCTION:o Job Production:

To produce a variety of jobs within a group in a limited quantity only, by groupwe mean the type of machinery setup.

It uses general purpose machines so that variety of jobs could be made; use oftools, jigs, fixtures is very common.

No prior planning is possible. Skilled man power is required to work on different jobs and depend more on

skill of workers.

o Batch production: Batch of an object is processed in a sequence of steps. Each step may possess

a single machine or a multiple machine. Garment manufacturers, threading

operations, sheet metal jobs, forging, book parts, paints, vegetable oil etc.

Most common type of production. A batch of objects (of specified sizes) is produced. Division of labor is possible.

o Mass production: Computers, mobile phones, automobiles, soft drinks, pharmacy products etc. Specialized (SPM) are used. Involve heavy fixed cost/modern plants. Little material handling. Plant layout is designed well.

o Continuous Production: Plant layout/process equipment is different from manufacturing unit. Safety parameters have to be high. Semi-skilled/skilled workers are employed. Material handling is automatic. Via buckets, trolleys, belt conveyers, pipelines

etc.

- AUTOMATION ACHIEVEMENTS:Automation is the technology by which a process or procedure is accomplished without

human assistance. It is implemented using a program of instructions combined with a

controlsystem that executes the instructions, to automate a process power is required,

both to drive the process itself and to operate the program and control system. Although

automation can be applied in a wide variety of areas, it is most closely associated with

the manufacturing industries. It was in the context of manufacturing that the term was

originally coined by an engineering manager at Ford Motor Company in 1946 to describe

the variety of automatic transfer devices and feed mechanisms that had been installed inFord's production plants (Historical Note 3.1), It is ironic that nearly all modern

applications of automation are controlled by computer technologies that were not

available in 1946.


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- AUTOMATION PRINCIPLES & STRATEGIES:o USA Principle:

The USA Principle is a common sense approach to automation projects.Similar procedures have been suggested in the manufacturing and

automation trade literature, but none has a more captivating title than this

one. USA stands for' 1. Understand the existing process 2. Simplify the process

3. Automate the process. The article was concerned with implementation of

enterprise resource planning (ERP, Section 26.6), but the USA approach is '0

general that it is applicable to nearly any automation project. Going through

each step of the procedure for an automation project may in fact reveal that

simplifying the process is sufficient and automation is not necessary.

Understand the Existing Process. The obvious purpose of the first step inthe USA approach is to comprehend the current process in all of its details.

What arc the inputs? What are the outputs? What exactly happens to the

work unit between input and output? What is the function of the process?How does it add value to the product? What are the upstream and

downstream operations in the production sequence, and can they be

combined with the process under consideration?

Simplify the Process. Once the existing process is understood, then thesearch can begin for ways to simplify. This often involves a checklist of

Questions about the existing process. What is the purpose of this step or

this transport? Is this step necessary? Can this step be eliminated? Is the

most appropriate technology being used in this step? How can this step be

simplified? Are there. Unnecessary steps in the process that might be

eliminated without detracting from function? Some of the ten strategiesat automation and production systems (Section 1.5.2) are applicable to try

to simplify the process. Can steps be combined? Can steps be performed

simultaneously? Can steps be integrated into a manually operated

production line?

Automate the Process. Once the process has been reduced to its simplestform, then automation can be considered. The possible forms of

automation include those listed in the ten strategies discussed in the


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following section. An automation migration strategy (Section 1.5.3) might

be implemented for a new product that has not yet proven itself.

o Ten Automation Strategies: Following the USA Principle is a good first step in any automation project. As

suggested previously, it may turn out that automation of the process is

unnecessary or cannot be cost justified after it has been simplified. If

automation seems a feasible solution to improving productivity, quality, or

other measure of performance, then the following ten strategies provide a

road map to search for these improvements.

1. Speciattzauon of operations, The first strategy involves the use of

special-purpose equipment designed to perform one operation with the

greatest possible efficiency. This is analogous to the concept of labor

specialization, which is employed to improve labor productivity.

2. Combined operations. Production occurs as a sequence of operations.

Complex parts may require dozens, or even hundreds, of processing steps.

The strategy of combined operations involves .reducing the number of

distinct production machines or workstations through which the part must

be routed. This is accomplished by performing more than one operation at

a given machine, thereby reducing the number of separate machinesneeded. Since each machine typically involves a setup, setup time can

usually be saved as a consequence of this strategy. Material handling effort

and non-operation time are also reduced. Manufacturing lead time is

reduced for better customer service.

3. Simultaneous operations. A logical extension of the combined

operations strategy is to simultaneously perform the operations that are

combined at one workstation. In effect, two or more processing (or

assembly) operations are being performed simultaneously on the same

work part. Thus, reducing total processing time.

4. Integration of operations. Another strategy is to link several

workstations together into a single integrated mechanism, using

automated work handling devices to transfer parts between stations. In

effect, this reduces the number of separate machines through which the

product must be scheduled. With more than one workstation. Several parts

can be processed simultaneously, thereby increasing the overall output of

the system.

5. Increased flexibility. This strategy attempts to achieve maximum

utilization of equipment for job shop and medium-volume situations by

using the same equipment for a variety of parts or products, It involves the

use of the flexible automation concepts (Section 1.3.1). Prime objectives

are to reduce setup time and programming time for the productionmachine. This normally translates into lower manufacturing lead time and

less work-in-process.

6. Improved material handling and storage. A great opportunity for

reducing non-productive time exists in the use of automated material

handling and storage systems. Typical benefits include reduced work-in-

process and shorter manufacturing lead times.


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7. On-line inspection, Inspection for quality of work is traditionally

performed after the process is completed. This means that any poor-

quality product has already been produced by the time it is inspected.

Incorporating inspection into the manufacturing process permits

corrections to the process as the product is being made. This reduces scrap

and brings the overall quality of the product closer to the nominal

specifications intended by the designer.

8. Process control and optimization. This includes a wide range of control

schemes intended to operate the individual processes and associatedequipment more efficiently. By this strategy, the individual process times

can be reduced and product quality improved.

9. Plant operations control. Whereas the previous strategy was concerned

with the control of the individual manufacturing process, this strategy is

concerned with control at the plant level. It attempts to manage and

coordinate the aggregate operations in the plant more efficiently. Its

implementation usually involves a high level of computer networking

within the factory.

10. Computer-integrated manufacturing (CIM). Taking the previous

strategy one level higher. We have the integration of factory operations

with engineering design and the business functions of the firm; CIM

involves extensive use of computer applications, computer data bases, and

computer networking throughout the enterprise.

- CAD/CAM IN DIFFERENT AREAS OF OPERATION:CAD/CAM is concerned with the engineering functions in both design and

manufacturing. Product design, engineering analysis, and documentation of the

design (e.g. drafting) represent engineering activities in design. Process planning, NC

part programming, and other activities associated with CAM represent engineering

activities in manufacturing. The CAD/CAM systems developed during the 1970s and

early 1980s were designed primarily to address these types of engineering problems.In addition, CAM has evolved to include many other functions in manufacturing, such

as material requirements planning, production scheduling, computer production

monitoring, and computer process control. It should also be noted that CAD/CAM

denotes an integration of design and manufacturing activities by means of computer

systems. The method of manufacturing a product is a direct function of its design.

With conventional procedures practiced for so many years in industry, engineering

drawings were prepared by design draftsmen and later used by manufacturing

engineers to develop the process plan. The activities involved in designing the

product were separated from the activities associated with process planning.

Essentially, two-step procedure was employed. This was time-consuming andinvolved duplication of effort by design and manufacturing personnel. Using

CAD/CAM technology, it is possible to establish a direct link between product design

and manufacturing engineering. In effect, CAD/CAM is one of the enabling

technologies for concurrent engineering. It is the goal of CAD/CAM not only to

automate certain phases of design and certain phases of manufacturing, but also to

automate the transition from design to manufacturing. In the ideal CAD/CAM system,

it is possible to take the design specification of the product as it resides in the CAD


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data base and convert it into a process plan for making the product, this conversion.

being done automatically by the CAD/CAM system. A large portion of the processing

might be accomplished on a numerically controlled machine tool. As part of the

process plan, the NC part program is generated automatically by CAD/CAM; The

CAD/CAM system downloads the NC program directly to the machine tool by means

of a telecommunications network. Hence, under this arrangement, product design,

NC programming, and physical production are all implemented by computer.

UNIT 2

- MOTION CONTROL SYSTEMS:o Some NC processes are performed at discrete locations on the work part (e.g.,

drilling and spot welding). Others are carried out while the work head is moving

(e.g., turning and continuous arc welding). If the work head is moving, it may be

required to follow a straight line path or a circular or other curvilinear path. These

different types of movement are accomplished by the motion control system,

whose features are explained below. Point-to-Point versus Continuous Path

Control. Motion control systems for NC can be divided into two types: (1) point-

to-point and (2) continuous path.

Point-to point systems, also called positioning systems, move theworktable to a programmed location without regard for the path taken to

get to that location. Once the move has been completed, some processing

action is accomplished by the work head at the location. Such as drilling or

punching a hole. Thus, the program consists of a series of point locations

at which operations are performed, as depicted in Figure 6.3.


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Continuous path systems generally refer to systems that are capable ofcontinuous simultaneous control of two or more axes. This provides

control of the tool trajectory relative to the work part. In this case, the

tool performs the process while the worktable is moving, thus enabling

the system to generate angular surfaces, two-dimensional curves, or

three-dimensional contours in the work part. This control mode is

required in many milling and turning operations. A simple two-

dimensional profile milling operation is shown in Figure 6.4 to illustrate

continuous path control. When continuous path control is utilized to movethe tool parallel to only one of the major axes of the machine tool

worktable, this is called straight-cut NC. When continuous path control is

used for simultaneous control of two or more axes in machining

operations, the term contouring is used.

- APPLICATIONS OF NC IN METAL CUTTING:o Machining is a manufacturing process in which the geometry of the work is produced

by removing excess material. By controlling the relative motion between a cutting

tool and the work piece, the desired geometry is created. Machining is considered

one of the most versatile processes because it can be used to create a wide variety of

shapes and surface finishes. It can be performed at relatively high production rates to

yield highly accurate parts at relatively low cost. There are four common types of

machining operations: (a) turning, (b) drilling, (c) milling, and (d) grinding. Use of NC

is widely in the below four metal cutting processes.


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- APPLICATIONS OF NC IN NON-METAL CUTTING:o Electrical wire, wrap machines. These machines, pioneered by Gardner Denver

Corporation, have been used to wrap and string wires on the back pins of electrical

wiring boards to establish connections between components on the front of the

board. The program of coordinate positions that define the back panel connections isdetermined from design data and fed to the wire wrap machine. This type of

equipment has been used by computer firms and other companies in the electronics

industry.

o Component insertion machines. This equipment is used to position and insertcomponents on anx-yplane, usually a flat hoard or panel. The program specifics the

x and y-axis positions in the plane where the components are to be located.

Component insertion machines find extensive applications for inserting electronic

components into printed circuit boards. Machines are available for either. Through-

hole or surfaces mount applications as well as similar Insertion-type mechanical

assembly operations.

o Drafting machine.Automated drafting machines serve as one of the output devicesfor a CAD/CAM [computer-aided design/computer-aided manufacturing) system. The

design of a product and its components are developed on the CAD/CAM system.

Design iterations arc developed on the graphics monitor rather than on a mechanical

drafting board. When the design is sufficiently finalized for presentation, the output

is plotted on the drafting machine, basically a high speedx-yplotter.


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o Coordinate measuring machine. A coordinate measuring machine (CMM) is aninspection machine used for measuring or checking dimensions of a part. The CMM

has a probe that can be manipulated in three axes and Identifies when contact IS

made against a pan surface. The location of the probe tip is determined by the CMM

control unit. Thereby indicating some dimension on the part. Many coordinate

measuring machines are programmed to perform automated inspections under NC.

o Tape laying machines for polymer composites.The work head of this machine is adispenser of uncured polymer matrix composite tape. The machine is programmed to

lay the tape onto the surface of a contoured mold, following a back-and-forth and

crisscross pattern to build up a required thickness. The result is a multilayered panel

of the same shape as the mold.

o Filament winding machines for polymer composites.This is similar to the precedingexcept that a filament is dipped in uncured polymer and wrapped around a rotating

pattern of roughly cylindrical shape.

UNIT-3

- PREPARATORY G-CODES, MISCELLANOUS M-FUNCn CODES, COMMON WORD PREFIXES.


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