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Transcript of MIT 3710 - Methods Engineering Course
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MIT 3710
Methods Design
Welcome to the methods design course!
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INTRODUCTION
Instructor
Course
Syllabus
Grading
Text
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METHODS ENGINEERNING
Definition
“the systematic procedure for subjecting all direct and
indirect operations to close scrutiny in order to introduceimprovements that will make work easier to perform andwill allow work to be done in less time and with lessinvestment per unit”1 without an adverse effect upon quality
“Thus, the real objective of methods engineering is profitimprovement”1 through lowering unit cost by continuousImprovement of manufacturing processes.
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METHODS ENGINEERNING
Methods Engineering is simply a discipline of using
systematic analyses of processes, both proposed
and existing, in order to eliminate waste (“muda”).
Therefore, the tools and techniques of methods
engineering are very useful in achieving the goals
of lean manufacturing.
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METHODS ENGINEERING
With the detailed analysis of any job, you will find
waste. That can, almost, be guaranteed. The
causes and necessary corrective measures for the
waste will vary, making some corrective actioneasier than others (“low hanging fruit”).
Total work content Ineffective time
Total time content of an operation under current conditions
Minimum job content Process inefficiency issues shortcomings
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METHODS ENGINEERING
Some Typical Methods Engineering Functions
Design and develop processes
Design and develop tooling and fixtures Optimize operator and machine relationships Continuous improvement of workstation layouts Developing and maintaining work standards
The result of these efforts will be more efficient production bymaking work easier to perform, less time consuming, and lesscostly per unit produced.
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HISTORY
Frederick Winslow Taylor (1856 – 1915)2
“Father of Scientific Management” or modern time study
Began time study in 1881 at Midvale Steel Co.3
Presented findings in 1895 to ASME3
“Shop Management” presented to ASME in 19033
Scientific Management approach to work (see p. 28)
Innovations (see page 28 of text)
Early controversy with “efficiency experts”5
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HISTORY Are Taylor’s Principles Out of Date?
Read about Dr. Shigeo Shingo (page 33 of text)
and excerpts from The Visual Factory, by
Michel Greif, pages 61 through 66.
The techniques are still useful, today, and can
be key in implementing lean manufacturing byassisting in eliminating waste.
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History
Frank (1868-1924) and Lillian (1878-1972) Gilbreth4
Parents of motion study
Frank founded motion study around 1900 They developed many new techniques to study work
Elimination of wasted motion = “Work Simplification”
Developed 17 basic manual motions, “Therbligs”
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HISTORY
For some twenty years or so (ca. 1910 until 1930)
there were two groups conducting work study.
One group followed Taylor’s scientific
management approach and the other followed
the motion study techniques of the Gilbreths.
Finally, it was realized that the efforts of the twoshould be combined, and this led to what is
known by some as “methods engineering”.
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LEAN MANUFACTURING
Chapter two of the text has a nice, brief discussion about
“lean” in the manufacturing context. At the center of this
discussion is Dr. Shigeo Shingo, a world renowned
Japanese industrial engineer.
Dr. Shingo was a follower of Fred Taylor’s analytical
philosophy and Frank Gilbreth’s exhaustive pursuit of goals
and the single best method of doing a job.6
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LEAN MANUFACTURING
“The philosophy of Shigeo Shingo and its
application to motion and time study tools is the
basis for the lean environment approach.”7
The “lean production environment” focuses upon
the elimination of all forms of waste in
manufacturing. The term was coined by JamesWomack and is used to differentiate the practices
of Toyota from those of mass production.7
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LEAN MANUFACTURING
Lean involves an environment that will utilize the
efforts of the entire workforce to achieve the
elimination of waste (“muda”). This means that
anyone may use tools available through motion
and time study, quality and process control, or any
other traditional mass production system
functional area that may be helpful in achieving
lean manufacturing.8
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LEAN MANUFACTURING
Dr. Shingo attributes Toyota’s tremendous
improvements over their bleak situation in the1960s to the application of traditional motion and
time study problem-solving techniques, applied asneeded to obvious bottlenecks.9
The text presents Womack and Jones’ five-year
time frame for developing a lean organization, butthis is beyond the scope of this course. We willfocus upon motion and time study techniques.
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LEAN MANUFACTURING
Dr. Shingo pointed out the importance of analyses
of processes and operations, and motion and time
study techniques are designed for these
purposes.10
Process: a continuous flow by which raw materials are
converted to finished goods11
Operation: any action performed by man, machine, or
equipment on raw materials or intermediate or finished
products11
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MOTION & TIME STUDY Motion Study
As has been implied, motion and time study are
two different subjects, each with its own set of
tools or techniques.
Motion studies were conducted by the Gilbreths in
search of the “one best way” of doing a task.
These studies seek to eliminate wasted motion
and specify the proper way of completing a task.They were not concerned with cycle time, since
the proper method will have minimal cycle time.12
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MOTION & TIME STUDY Motion Study
The first step in process or operation improvement
should begin with motion study. It is with motion
study that you will, often, find the largest savings
opportunities.13
There are two sets of motion study tools. They are
referred to as:1. Macromotion: factory or process flow
2. Micromotion: operation or job
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MOTION & TIME STUDY Motion Study
Macromotion studies should be conducted prior to
micromotion studies for three reasons:
1. Macro savings are usually greater2. Macro may eliminate or change operations
3. Starting with micro could waste your time!
Of course there are appropriate times to conductmicromotion studies of operations without macro
studies, first.
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MOTION & TIME STUDY Motion Study
Improvement Actions14
(in priority sequence)
1. Eliminate if possible
2. Combine with another activity
3. Change or rearrange the sequence4. Simplify the activity as much as possible
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MOTION & TIME STUDY Time Study
Time study is a work measurement technique used
for the setting of a time standard. The text’s
author provides a definition of “time standard” as
follows:
“the time required to produce a product at a work
station with the following three conditions:
(1) a qualified, well-trained operator,(2) working at a normal pace, and
(3) doing a specific task”15
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MOTION & TIME STUDY Time Study
Definitions (ANSI)
Time study: is a work measurement technique consistingof a careful time measurement of a task with a time
measuring instrument, with appropriate adjustments for
work pace, unavoidable delays, and personal needs. It is
used to determine the time required by a qualified and
trained person working at normal pace to do a task
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MOTION & TIME STUDY Time Study
Definitions (ANSI)
Qualified operator: A worker who, by virtue of his/her
training, skill, and experience, is able to perform a task
within acceptable quality and time limits.
Normal pace: the manual pace required to produce an
acceptable amount of work by a qualified operator followinga prescribed method under standard conditions with an
effort that does not incur cumulative fatigue from day to day(considered 100% and often referred to as “100% pace”)
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MOTION & TIME STUDY Time Study
Proper procedure is to always conduct
motion study (or methods study)prior
to conducting the time study!
Why do you think this is true?
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MOTION & TIME STUDY Work Measurement
Definition (ANSI)
Work measurement: is a generic term used to refer to thesetting of a time standard by a recognized industrial
engineering technique
What are these “recognized industrial engineering techniques”?
(Also referred to as work measurement techniques.)
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MOTION & TIME STUDY Work Measurement
Work Measurement Techniques16
1. Time study
2. Standard data3. PTS (pre-determined time systems)
4. Work sampling (ratio-delay studies)
There are two other techniques for setting time standards,but they are not work measurement techniques. They are
historical data and estimates. We will discuss these, later.
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MOTION & TIME STUDY Work Measurement
Time Study
The most commonly used technique
Uses a time measurement instrument Follows a specific procedure: (after proper method determined)
Job is broken into elements
Each element is timed
Performance rating is necessary Allowances must be added
Standard time is calculated
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MOTION & TIME STUDY Work Measurement
Standard Data
Time formulas used to calculate standard times
Linear regression graphs used to depict rates/times Requires much time, effort, and documentation
Most cost effective way of setting time standards
Most consistent method of setting time standards
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MOTION & TIME STUDY Work Measurement
Pre-Determined Time Systems (PTS)
Developed through research, including film analysis
Body motions are broken into basic elements Forces methods analysis (motion study)
Can set standards prior to actual production
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MOTION & TIME STUDY Work Measurement
Work Sampling18
Based upon the laws of probability
Random samples (observations) Samples taken have the same pattern as population
Also referred to as “ratio-delay studies”
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MOTION & TIME STUDY Work Measurement
Not Work Measurement Techniques
Historical Data
Standards based upon similar jobs previously produced19 Uses actual clock hours on similar work
Builds in inefficiencies of previous work
Estimates Based upon “expert” opinion (often the supervisor)
Commonly used prior to time study
Lacks in accuracy (avg. deviation from actual time = 25%)19
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MOTION & TIME STUDY Importance and Uses of Time Study
Time standards provide goals for production. It has been
estimated that organizations that operate without time
standards only achieve about 60% performance. With time
standards, the performance improves to an average of85%, or a forty-two percent improvement!
Rules of thumb:
Plants without standards average 60%
Plants with time standards average 85%
Plants with incentive systems average 120%17
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MOTION & TIME STUDY Importance and Uses of Time Study
Lets look at the material presented in the text on
pages 43 through 57.
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MACROMOTION STUDY
As was mentioned earlier, the overall process flow
should be studied prior to analysis of individual
jobs, and the macromotion techniques are
designed for this purpose.20
Take a look at what the author of the text refers to
as the “Cost Reduction Formula” (p. 68). Thistable summarizes the actions of the methods
engineer when conducting a macromotion study.
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MACROMOTION STUDY
In order to eliminate waste and improve your
manufacturing facility’s processes, it is important
to, first, understand the product flow through the
entire organization. Macromotion tools allow you
to develop this knowledge in a systematic way.
The simple procedure outlined in the “Cost
Reduction Formula” will lead to this knowledge.
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MACROMOTION STUDY
All motion study tools have been developed to
assist in the analysis of processes or operations.
These tools may be tweaked by the analyst to fit a
particular need, so let your imagination flow andutilize the tools as they best fit your specific need.
Let’s, briefly, look through part of chapter 5 to see some of what the text’s author presents, beginning
on page 69.
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MACROMOTION STUDY Flow Diagram, Fig. 5-1
Elimination of handling & travel by relocating press & receiving castings at back door.
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MACROMOTION STUDY
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MICROMOTION STUDY
The micromotion study tools and techniques are
designed to focus upon an individual job or activity.
As was pointed out earlier, these studies should be
completed after macromotion study.
Do you remember why?
The goal of micromotion study is to eliminate
waste on the operation level.
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PRACTICEProcess Charting
We will review the process chart form (to be handed out) in
order to understand its format, then you will be given a
task, already broken into elements, to transfer to the form.
Complete these steps for this “present method”:
Fill in the header information so the details will not be lost
Write in each element and mark the appropriate symbol
Document any distances traveled
Fill in appropriate quantities
Enter task element times
Complete the “Summary” information
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OPERATOR-MACHINE CHARTMicro-Motion Technique
What is it?a chart showing the exact relationship in time between the
working cycle of the person and the operating cycle of the
machine or machines21
When is it used?to analyze one work station
Why is it used?to reduce waste (lower unit cost) by identifying inefficient
utilization of the operator and/or machine’s time
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OPERATOR-MACHINE CHART
How does it work?
Breaks person & machine’s work into elements
Charts the exact time for each, to scale, side by side Clearly shows idle time for each (operator and machine)
Improvement possibilities are identifiable
“Machine coupling” possibilities are evident
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OPERATOR-MACHINE CHARTFig. 6-2 (current) (pp. 93 - 95 of Text) Fig. 6-3 (new)
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OPERATOR-MACHINE CHARTWe will use this format.
This is an example of an alternate format for Fig. 6-3.Drawn to Scale
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OPERATOR-MACHINE CHART
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PRACTICEOperator-Machine Chart (page 1 of 4)
On grid paper, to be provided by the instructor, and using a
pencil, construct an operator-machine chart, given the
following information:
One operator is operating one machine
Operator loading the machine requires 0.250 minute
Operator unloading the machine requires 0.250 minute
The machine is unloaded just prior to loading
The machine’s cycle time is 0.500 minute The machine produces one unit per cycle
Leave space on the chart for adding additional machines!
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PRACTICEOperator-Machine Chart (page 2 of 4)
After constructing the operator-machine chart, answer the
following questions:
How much idle time per cycle does the operator experience?
How much idle time per cycle is being experienced by the machine?
How many “normal” units per minute are being produced?
How many units per shift should be expected of this operation?*
* Allowances are 10% for this operation (Allowance Factor = 1.10)
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PRACTICEOperator-Machine Chart (page 3 of 4)
Add a second, identical machine to the chart,
given the following information:
One operator is operating both machines
Operator loading requires 0.250 minute for each machine Operator unloading requires 0.250 minute for each machine
The machines are unloaded just prior to loading
The machines, each, have a cycle time of 0.500 minute
Walk time between the machines is 0.100 minute (one way)
Each machine produces one unit per cycle
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PRACTICEOperator-Machine Chart (page 4 of 4)
After constructing the operator-machine chart with an
additional machine, answer the following questions:
How much idle time per cycle does the operator experience?
How much idle time per cycle does each machine experience?
How many “normal” units per minute are being produced?
How many units per shift should be expected of this operation?*
* Allowances are 10% for this operation (Allowance Factor = 1.10)
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WORK STATION DESIGN
Chapter 7 in the text is divided into three sections:
Work Station Design Top view of workstation usually depicted
Include a layout of the entire work area
Show all materials used (raw and finished) Include all fixtures and tools needed
Principles of Motion Economy Initiated by the Gilbreths but added to over the years22
Leads to more efficient and easier jobs Motion Patterns
Depicts paths of both hands during the work cycle
Jobs are divided into “elements”
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WORK STATION DESIGN
The “Principles of Motion Economy” can be broken intothree subdivisions:23
1. The use of the human body
2. The arrangement of the workplace
3. The design of tools and equipment
By the titles of the subdivisions, it is easy to see the close
relationship between motion economy and ergonomics and
human factors.
Ergonomics: “the study of the interface (or interaction) between
humans and the objects they use and the environments they function
in”24
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WORK STATION DESIGN
Turn to page 111 of the text,
and we will look through the motion economypoints made by Meyers
More complete lists of principles and discussions can be found in
Barnes’ or Neibel’s books (listed in the bibliography).
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TIME STUDY
Remember that time study is the most frequentlyused method of developing a time standard.25
Also, recall that a time standard is “the time
required to produce a product at a work station
with the following three conditions:
(1) a qualified, well-trained operator,
(2) working at a normal pace, and
(3) doing a specific task”15 (following the prescribed method)
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TIME STUDY Tools
What tools are necessary to conduct a study?
Stopwatch (select appropriate type)
Form Clipboard
Pencil & eraser
Calculator
Tachometer (if needed for belt or shaft speeds)
Videotape recorder (if appropriate or needed)
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TIME STUDY Types
There are two basic types of time study. They are:
Continuous watch runs continuously during the study
reading is noted at end of each element much clerical work required
preferred method by some – forces discipline
Snap-Back watch snapped back to zero at end of each element
less clerical work and easier to conduct
Must be disciplined to avoid neglecting delays, etc.
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TIME STUDY Procedure
Let’s look through and discuss pages
172 through 184 of the text.
TIME STUDY
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TIME STUDY Procedure
T ST D
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TIME STUDY Number of Observations
The following is the formula I prefer, where:
N = number of observations (samples)
s = standard deviation (calculated) t = value from table
k = accuracy desired (given) = sample mean (calculated)
2
xk
st N
x
TIME STUDY
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TIME STUDY Number of Observations
Given the following information from a time study, calculate the
number of observations necessary to provide 95% confidence that
our sample mean is within +/- 5% (accuracy) of the true mean for
the job element.
Element Observed Times “t”n-1 distribution table value = 2.262
0.023 minute 0.019
0.020 0.023
0.025 0.025
0.022 0.027
0.023 0.0232
xk
st N
TIME STUDY
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TIME STUDY Continuous
TIME STUDY
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TIME STUDY Performance Rating
Rating , leveling , and normalizing are all terms that
refer to the same process of adjusting the observed time to
perform an operation to the time that should be required,
keeping in mind the definition of standard time:
“the time required to produce a product at a work station
with the following three conditions:
(1) a qualified, well-trained operator,(2) working at a normal pace, and
(3) doing a specific task”15
TIME STUDY
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TIME STUDY Performance Rating
More simply put: Performance rating is leveling
the actual observed time to the time it should take
to complete the task (“normal” time).
Rating performance is considered the most difficult and
debated portion of time study, and there have been a
number of attempts to remove the subjectivity of rating by
devising systems that objectively determine the rating
factor; however, simplicity has won out over the years!
TIME STUDY
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TIME STUDY Performance Rating
Of all the more complicated systems developed, probably
the most popular was the “Westinghouse System” or “LMS
System”, named for its developers: Lowry, Maynard, and
Stegemerten. This system, published in 1927, rates fourfactors:26
1. Skill (qualified and trained - not learning the job)
2. Consistency (an indication of skill)
3. Conditions (working conditions are not often a factor)4. Effort (the most important factor - operator’s speed)27
TIME STUDY
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TIME STUDY Performance Rating
“Speed rating” (or “performance rating”) is by far
the most widely used rating system.28 It is, also,
the simplest, since it rates only one factor, effort or
the speed/pace/tempo of the operator.
The time study analyst must have a good understanding of
normal pace for his/her industry. It is necessary to have
knowledge of the jobs studied, to include safety and qualityrequirements, tolerances of parts, and extra care demands
(highly polished surfaces, etc.)
TIME STUDY
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TIME STUDY Performance Rating
Normal Pace Benchmarks for Effort29
Walking 264 feet in 1.000 minute (3 mph) Dealing 52 cards in 0.500 minute
30 pins into a pin-board in 0.435 min.
TIME STUDY
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TIME STUDY Performance Rating
In order to normalize or level the observed time,
you simply apply the performance rating factor
(PRF) to the average observed time.
Observed time x PRF = normal time
The PRF is, simply, your rating of the operator’s
effort. For example, if you feel the operator isworking at 90% of normal, the PRF is 0.90. If your
rating is 110%, the PRF is 1.10.
TIME STUDY
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TIME STUDY Performance Rating
Let’s assume we are in the process of a time study of a job
with three elements and have the following observed times
and ratings:
Elem. Avg. Observed Time Rating Normal Time
1 0.033 minute 90%
2 0.157 95%
3 0.082 105%
Calculate the normal times for each element of this job.
TIME STUDY
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TIME STUDY Performance Rating
When do I rate the operator’s performance?
As you know, jobs are divided into elements prior to a time
study, and each element is timed. Some analysts rate the
performance of each element (53%), some rate each
observation (13%), and some rate the overall job (34%).30
However you prefer to do it, the rating must be done while
watching the operator, not at your desk, later.
Remember, performance rating is not for machine time!
TIME STUDY
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TIME STUDY Performance Rating
Concept of Normal Performance & Human Capability32
Approximately 95% of the industrial workforce (18-65)
are capable of achieving 100% (normal) performance The average worker can achieve 120% performance
The degree of variation in workers’ capabilities is a
ratio of around 1:2
Max. human performance capability is about 160%
(Sketch normal curve on board depicting the above)
TIME STUDY
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TIME STUDY Performance Rating
Why isn’t a process achieving 100% performance? 32
Worker(s) not following the prescribed method
Inadequate delay allowances (discuss later) Inexperienced workers (“learning curve”) – not qualified
Materials out of specification
Equipment or tooling failure (down time) – poor PMs
Incapable workers allowed to remain in workforce
TIME STUDY
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TIME STUDY Performance Rating
Performance rating practice!
TIME STUDY
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TIME STUDY Allowances
If the normal time to complete a unit of production
is 1.000 minute, how many units should be
expected at the end of an eight-hour shift?
480?
(There are 480 minutes in an eight-hour shift.)
No! Why not ??
TIME STUDY
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TIME STUDY Allowances
The final step to arrive at a fair standard is to
include time for basic needs during the shift.
These basic needs fall into three categories:
1. Personal
2. Fatigue (if applied, only to the effort portion)
3. Unavoidable Delays
(These are commonly referred to as “P,F,&D” allowances.)
TIME STUDY
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TIME STUDY Allowances
“The fundamental purpose of allowances is to add
enough time to the normal production time to
enable the average worker to meet the standard
when performing at a normal pace.”31
To be realistic, the accepted lost production time
during the shift must be factored into the time to do
the work to arrive at an accurate standard.
TIME STUDY
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TIME STUDY Allowances - Personal
The personal allowance generally includes things like:
trips to the restroom
trips to the drinking fountain adjusting safety equipment or cleaning glasses
TIME STUDY
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TIME STUDY Allowances - Fatigue
The fatigue allowance is cause for debate in many work
measurement circles. With modern workplace comforts
and conveniences, the fatigue allowance is often
unnecessary and may be considered covered by the
morning and afternoon breaks.
Fatigue allowance should not be added unless a loss of
production is experienced due to fatigue or monotony.
How do I know if production is lost due to fatigue?
TIME STUDY
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TIME STUDY Allowances - Fatigue
There have been a number of methods devised in an
attempt to measure fatigue created by work. These have
included:
physical tests (work rate) chemical tests (body fluids)
physiological tests (pulse, BP, oxygen consumption)
However, the most often used method attempting tomeasure fatigue is measuring the decline of production
during the day.33
TIME STUDY
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TIME STUDY Allowances - Delays
Only acceptable unavoidable delays that enhance or arenecessary for production to occur are to be considered forinclusion in allowances. If a delay is avoidable, eliminate it!You, certainly, do not want to accept lost production time
due to an avoidable issue.
Some unavoidable delay examples:
receiving set-up instructions discussing quality issues with supervisor or quality inherent equipment demands (adjustments, etc.) removing and putting on safety equipment (at breaks) clean-up time (end of shift)
TIME STUDY
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TIME STUDY Allowances
How is the allowance percentage calculated? 34
Allowances are a percentage of production time, so the
correct method of determining the allowance percentage
includes removing non-productive time from the calculation.
The total percentage allowance calculation is:
Allowance = allowance min. / (shift min. – allowance min.)
Allow. Factor (AF) = shift min. / (shift min. – allow. min.)
TIME STUDY
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TIME STUDY Allowances
How are allowances determined? 35
Allowances are usually determined by work
sampling. They may, also, be determined throughdelay studies (production studies), but these are
very demanding.
TIME STUDY
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TIME STUDY Allowances
Given the information, below, from a study to determine
appropriate allowances for a production area, calculate the
total allowance percentage and the allowance factor (AF).
Personal time 15 minutes Fatigue time 20 minutes (breaks)
Delays: (Unavoidable)
Start-Up at beginning of shift 2 minutes
Communications with supervisor 5 minutes Remove & put on safety equip. 6 minutes
Clean up at end of shift 7 minutes
TIME STUDY
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TIME STUDY Allowances
Given the time and effort put into developing an accurate
standard time, applying an arbitrary allowance factor
should be avoided. This would only destroy the accuracy.
In addition, be aware of how allowances are applicable,
since they may be applied to three different categories of
work. Every allowance time may not apply to every job.
allowances applicable to the total cycle time allowances applicable to the machine time, only
allowances applicable to the effort time, only36
STANDARD TIME
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STANDARD TIME
Recall the definition of a time standard or standardtime:
“the time required to produce a product at a work
station with the following three conditions:
(1) a qualified, well-trained operator,
(2) working at a normal pace, and
(3) doing a specific task”15 (following the prescribed method)
(Standard time is sometimes referred to as “allowed time” or “standard allowed time”.)
STANDARD TIME
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STANDARD TIME
We have, now, covered all the steps necessary to
determine the standard time to complete a task,
using time study. In summary, they are:
Develop the proper method (micro-motion study)
Determine the average observed time
Performance rate the operator
Calculate the normal time for the task
Apply the allowance factor
STANDARD TIME
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STANDARD TIME
For the sake of simplicity, let us assume that the followingobserved times were taken for the completion of a one-
element task. Calculate the standard time for this job.
Performance rating: 90% (overall)Allowances: 15%
Observed times (minutes):
0.100 0.090 0.130 0.110 0.100
0.110 0.120 0.110 0.100 0.090
0.120 0.100 0.120 0.110 0.110
STANDARD TIME
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STANDARD TIME
What would be the standard number of units expected fromthe previous operation:
per minute:
per hour: per shift:
If you went out to watch the operation, what should be the
rate of production (in units per minute)?
Have enough observations been taken (for 95%, +/- 5%)?
STANDARD TIME
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STANDARD TIME
Calculate the Standard Time
(Times shown in hundredths of a minute. Standard allowance is 12%)Element C Y C L E S Normal
Description 1 2 3 4 5 6 7 8 9 10 Avg. PR Time
1. Unit to 5 6 4 5 5 6 5 7 5 5 90
Bench
2. Assemble 17 15 17 18 14 17 16 15 17 37 90
3 screws
3. Assemble 10 9 9 8 11 10 9 10 11 9 110
handle
4. Assemble 20 19 22 18 23 17 20 21 22 20 85
Brace
5. Aside to 4 5 7 5 6 5 5 7 5 7 90
conveyor
STANDARD TIME
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STANDARD TIME
Calculate the Standard Time
Element C Y C L E S Normal
Description 1 2 3 4 5 6 7 8 9 10 Avg. PR Time
1. Unit to 5 6 4 5 5 6 5 7 5 5 0.0530 90 0.0477
bench
2. Assemble 17 15 17 18 14 17 16 15 17 37 0.1622 90 0.1460 3 screws
3. Assemble 10 9 9 8 11 10 9 10 11 9 0.0960 110 0.1056
handle
4. Assemble 20 19 22 18 23 17 20 21 22 20 0.2020 85 0.1717
brace
5. Aside to 4 5 7 5 6 5 5 7 5 7 0.0560 90 0.0504
conveyor
Total Task Normal Time: 0.5214
Task Standard Time: 0.584 m/u
STANDARD TIME
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STANDARD TIME
Handout time study problem
-- standard time calculation practice --
times are in minutes
assume enough observations for desired accuracy
Process time for equipment is rated at 100%
Resupply and other occasional tasks are pro-rated
STANDARD DATA
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STANDARD DATA Definition
Standard Data
(ANSI)
“… a structured collection of normal time values for work
elements codified in a tabular or graphic form. The datais used as a basis for determining time standards onwork similar to that from which the data was collected
without making additional studies.”
STANDARD DATA
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STANDARD DATA
Levels of Standard Data
Motion = the most detailed and flexible butrequires more time to apply
Element = Data that covers an entire element ofa task. It is less flexible than motion but quickerto apply.
Task = data that covers a complete task, notflexible but very fast
STANDARD DATA
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STANDARD DATA
When developing standard data, you mustdistinguish between “constant” and “variable”
portions of the task.37
constant = This portion of the job will not changesignificantly even though the part being producedchanges; therefore the time to perform this portionof the job will remain the same.
variable = time requirements change with partcharacteristics (dimensions, weight, etc.)
STANDARD DATA
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Let’ s look at examples of
> motion> element
> task
standard data
STANDARD DATA
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STANDARD DATA
Turn to page 213 in the text,
and we will review Meyers’ list of
advantages of standard data.
METHODS ENGINEERING
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METHODS ENGINEERINGand the Product Life Cycle
Let’s look at a couple of things that may
assist in the understanding of when methods
work applies during the product life cycle.
Product Life Cycle
Continuous Improvement Cycle
LINE BALANCING
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LINE BALANCING
Very often, situations are encountered whereseveral operators will be performing work as a
single production unit. Each operator has a
specific portion of the product to assemble, andafter all the operators have completed their portion
of the work, the product is completed.
These operations may be connected by means ofa conveyor or may be in close proximity so that
parts are easily passed from one to the other.
LINE BALANCING
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LINE BALANCING
Purposes of Assembly Line Balancing38
Equalize workload among the assemblers
Identify the bottleneck operation
Establish the speed of the assembly line Determine number of work stations/operators
Determine labor cost
Establish workload of operators Assist in plant layout
Reduce production cost
LINE BALANCING
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N N NG
Sketch assembly line examples on the board.
Identify the “line balance” operation
Calculate the standard time per unit
Determine the normal time production rate
Stress the importance of balancing work
Discuss the significance of the “bottleneck”
Calculate “percent line balance”
LINE BALANCING
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Given the information, below, for an assembly line, answer or calculate the
requested information:
Seven operations & operators: (the standard minutes include 12% allowance)1. 0.372 std. min.
2. 0.237
3. 0.389
4. 0.2735. 0.279
6. 0.155
7. 0.333
Identify the “bottleneck” or “line balance” operation
Calculate the standard time (in minutes) per unit How many units per 8-hour shift are expected?
At what production rate (units per minute) should this line be running?
LINE BALANCING
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LINE BALANCING
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Some Thoughts for Improving Output
Assign a portion of the line balance operation’s
work to another station
Improve the method of the line balance station(may or may not require capital investment)
Utilize an additional operator at the line balancestation, full or part-time
Work bottleneck operation overtime in order toaccumulate units from which to supplement
PERFORMANCE
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In order to assist in maintaining proper efficiencyand performance, production data are collected
and measurements made of actual results versus
expectations. One of the measures used isperformance against standard.
100% X ActualTime
EarnedTimeePerformanc
PERFORMANCE
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Recall this problem worked earlier. Performance against standard, based upon
a given amount of production, has been added to the calculations, below.
Seven operations & operators: (the standard minutes include 12% allowance)1. 0.372 std. min.
2. 0.237
3. 0.389
4. 0.2735. 0.279
6. 0.155
7. 0.333
Identify the “bottleneck” or “line balance” operation
Calculate the standard time (in minutes) per unit How many units per 8-hour shift are expected?
At what production rate (units per minute) should this line be running?
What is the performance vs. standard if 1,150 units are produced in 8-hours?
PERFORMANCE
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The percent performance versus standardcalculation is used for all production work, whether
single operator work or assembly line.
For example:
A single operator bench assembly job has a
standard time of 1.233 minutes. What is this job’seight-hour performance if 400 units are produced?
PERFORMANCE
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Effect of Performance on Actual Labor Cost
1/performance x labor rate = actual labor cost
(The performance number is not in percent.)
Calculate the actual cost of labor given these assumptions: One operator bench assembly (from previous problem)
Operator earns $12.00 per hour
Operator produces 330 units in one 8-hour shift (std = 1.233 min.)
This calculation is possible for a part, a department, or the entire plant.
PERFORMANCE
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Your plant manager is interested in a better understanding of yourplant’s labor cost. You decide to compute the effective actual direct
labor hourly wage rate, based upon the current labor standards, for the
past month. You have recently performed an audit of the standards
and are comfortable with their accuracy. Here are the assumptions:
Total hours earned (all products produced) 13,700 hours
Total hours used (100 people for 20 work days) 16,000 hours
Weighted average direct labor hourly wage rate $13.50
13,700 / 16,000 = 0.856 1 / 0.856 = 1.168 1.168 x $13.50 = $15.77
This information could be used as a benchmark from which to measure
improvements. It could, also, include indirect labor, if desired.
PRACTICE PROBLEMS
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HANDOUT
Perform the calculations required to answer thequestions on the practice problems.
BIBLIOGRAPHY
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(Page 1 of 2)
Greif, Michel, The Visual Factory,Productivity Press, 19896. p. 63
Barnes, Ralph M., Motion and TimeStudy Design and Measurement ofWork, 7th edition, John Wiley & Sons,
198018. p. 40622. p. 17423. p. 17526. p. 28928. p. 29130. p. 284
34. p. 309
Niebel, Benjamin W., Motion and TimeStudy, seventh edition, Irwin, 19821. p. 63. pp. 10 & 115. p. 1219. p. 29421. p. 134
31. p. 40133. p. 39135. pp. 386 & 38736. p. 38637. p. 420
Alexander, David C. and Pulat, BaburMustafa, Industrial Ergonomics APractitioner’s Guide, IndustrialEngineering and Management Press(IIE), 198524. p. 3
BIBLIOGRAPHY
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(Page 2 of 2)
Meyers, Fred E. and Stewart,James R., Motion and Time Studyfor Lean Manufacturing, thirdedition, Prentice-Hall, 20022. p. 274. pp. 29 – 317. p. 88. pp. 9 & 109. p.1310. pp. 22- 2411. p. 1312. pp. 37 & 38
13. p. 4014. p. 3815. p. 4116. p. 57
Meyers, Fred E. and Stewart,James R., Motion and Time Studyfor Lean Manufacturing, thirdedition, Prentice-Hall, 2002(continued)
20. p. 67
25. p. 15927. p. 186
29. p. 186
38. p. 233
Karger, Delmar W. and Hancock,Walton M., Advanced WorkMeasurement, Industrial Press,1982
32 17 21