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Motion and Time Study
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Motion and time study can reduce and control costs, improve working
conditions and environment, and motivate people.
The basic purpose is to improve the work and to reduce waste.
1. Motion analysis techniques
2. Time study techniques
3. Uses of time standards.
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Manufacturing management and engineering students are being prepared
to design work stations, develop efficient and effective work
methods, establish time standards, balance assembly lines, estimate
labor costs, develop effective tooling, select proper equipment, and
layout manufacturing facilities.
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However, the most important thing is to learn how to train
production workers in these skills and techniques so they can become
motion and time conscious.
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Motion study offers a great potential for savings in any area of
human
effort. We can reduce the cost by combining elements
of one task with elements of another.
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Motion study uses the principles of motion economy to develop work
stations that are friendly to the human body and efficient in their
operation.
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Motion study must consider the operator’s safety
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Time study can reduce cost significantly well. Time standards are
goals to strive for. In organizations that operate without time
standards, 60% performance is typical.
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When time standards are set, performance improves to an average of
85%. This is a 42% increase in performance:
85 % - 60 %
------------------ = 42% performance increase.
60%
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Incentive systems can improve performance even further.
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Incentive system
performances average 120%, that is another 42% increase in
performance:
120% - 85%
---------------------- = 42% performance increase.
85%
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Manufacturing plants with no standards average 60% performance.
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Manufacturing plants with time standards average 85% performance.
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Manufacturing plants with incentive systems average 120%
performance.
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If additional production output is required, don’t buy more
machinery, don’t add a second shift, and don’t build a new plant.
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Just establish a motion and time study program.
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Motion and time study is considered to be the backbone of industrial
engineering, industrial technology, and industrial management
programs because the information that time studies generate affects
so many other areas, including the following:
1. Cost estimating
2. Production and inventory control
3. Plant layout
4. Materials and processes
5. Quality
6. Safety
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Motion study comes first
before the setting of time standards. Motion study is
a detailed analysis of the work method in an effort to improve it.
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Motion studies are used to
1. Develop the best work method.
2. Develop motion consciousness on the part of all employees.
3. Develop economical and efficient tools, fixtures, & production
aids.
4. Assist in the selection of new machines and equipment.
5. Train new employees in the preferred method.
6. Reduce effort and cost.
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Motion study is for cost reduction, and time study is for cost
control. Motion study is the creative activity of motion and time
study.
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Motion study is design, while time study is measurement.
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Once the importance of motion and time study is understood and
accepted, the techniques of motion and time study are introduced.
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Flow diagrams
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Multi activity charts
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Operation charts
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Flow process charts
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Process charts
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Operations analysis chart
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Work station design
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Motion economy
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Flow patterns
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Predetermined time standards system (PTSS).
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The techniques of time study start with the last motion study
technique, which shows the close relationship between motion study
and time study. The techniques of time study are:
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Predetermined time standards system (PTSS)
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Stopwatch time study
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Standard data formula time standards
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Work sampling time standards
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Expert opinion and historical data time standards.
WHAT IS A MOTION STUDY?
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Motion studies are performed to eliminate waste.
Before any improvement in quality or quantity of output, any
study of operations time, any scheduling of work or balancing of
workload or any calculation of standard time, a study of the current
and proposed method is required.
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Studies of overall factory flow or process, called
macromotion
studies,
and then additional studies of detail or operations, called
micromotion
studies,
should be completed for a project.
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Motion studies were conducted by Frank and Lillian
Gilbreth about a century ago in a search
for the “one best way.” It is important to note that such
studies seek to
minimize
and
simplify
manual efforts.
Macromotion
Study
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Any process can be studied by dividing it into process activity.
Although each activity is different, depending on the product, there
are five classes of activities that are included in all processes.
Savings, may be found in the process by
reorganizing activities.
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These activities found in every sequence of processes are
Operations
Changes in the properties of the product
Transportations Changes in the location of the product
Inspection
Confirmation that change fits to specification
Delay Wait for start of
operation, transportation, or inspection
Storage
Wait until needed
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When the process is first studied, each activity is recorded and
arranged into one of the five classes. All observed activities are
recorded, and activities not done are not recorded. The purpose of
each activity should be studied.
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Typically, the questions Who? What?
Where? When? Why? and How?
must be answered. Next, each event is
observed in the following sequence:
Can the activity be eliminated? If not,
Can the activity be combined and done with another activity? If not,
Can the activity be rearranged so occur in the sequence at an easier
time? If not.
Can the activity be simplified with shorter distances, mechanical
assist, or reduced complexity?
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Once these questions are asked and the improvement sequence is
defined, it is necessary to draw a chart or diagram that shows the
motion improvements.
Process Flow Plan
A
plan-view plant layout with activities overlaid
Process Operations Chart
The
sequence of serial and parallel operations
Process Chart
All serial activities on a
preprinted form
Flow Process Chart
All
serial and parallel activities on a single page
Work Cell Load Chart
A
plan view with repetitive operations
Route Sheet
A planning tool for scheduling
operations
Micromotion
Study
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Considerable wasted motion and idle time can occur within an
operation. This time can’t be found with
macromotion studies because is usually within one process
operation. The improvement is gained from reducing the operation
cycle
time.
WHAT IS A TIME STANDARD?
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The definition of 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,
(3) doing a specific task.”
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These three conditions are essential to the understanding of time
study.
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The importance of time standards can be shown by the three
statistics 60%, 85%, and 120% performance.
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The time standard is one of the most important pieces of information
produced in the manufacturing department. It is used to develop
answers for the following problems:
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Determining the number of machine tools to buy
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Determining the number of production people to employ
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Determining manufacturing costs and selling prices
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Scheduling the machines, operations, and people to do the job and
deliver on time
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Determining the assembly line balance, determining the conveyor belt
speed, loading the work cells with the correct amount of work, and
balancing the work cells
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Determine individual worker performance and identifying operations
that are having problems so the problems can be corrected
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Paying incentive wages for outstanding team or individual
performance
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Evaluating cost reduction ideas and picking the most economical
method based on cost analysis, not opinion
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Evaluating new equipment purchases to justify their expense
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Developing operation personnel budgets to measure management
performance.
How would you answer the following questions without time standards?
How Many Machines Do We Need?
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One of the first questions rose when
setting up a new operation or starting production on a new product
is “how many machines do we need?” The answer depends on two pieces
of information:
a. How many pieces do we need to manufacture per shift?
b. How much time does it take to make one part? (Time standard)
EXAMPLE
1.
The marketing department wants us to make 2,000 wagons per
8-hour shift.
2. It takes us 0.400
minutes to form the wagon body on a press.
3. There are 480
minutes per shift (8 hours/shift x 60 minutes/hr).
4. - 50 minutes
downtime per shift (breaks, clean-up, etc.)
5. There are 430
minutes per shift available @ 100%.
6. @ 75% performance
(based on history) (0.75 x 430 = 322.5).
7. There are 322.5
effective minutes left to produce 2,000 units.
322.5
8.
---------------- = 0.161 minutes per unit, or 6.21 parts per
minute.
2,000 units
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The 0.161 minutes per unit is plant rate. Every operation in the
plant must
produce a part every 0.161 minutes; therefore, how
many machines do we
need for this operation?
Time standard = 0.400
minutes/unit
----------------------------------------------------- = 2.48
machines
Plant rate = 0.161 minutes/unit
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This operation requires 2.48 machines. If other operations are
required for this kind of machine, we would add all the machine
requirements together and round up to the next whole number.
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In this example, we would buy three machines. (Never round down on
your own. You will be building a bottleneck in your plant.)
How Many people should we hire?
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Look at the operations chart shown in Figure 4-1.
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From a study of this chart, we find the time standard (or every
operation required to fabricate each part of the product and each
assembly operation required to assemble and pack the finished
product.
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In the operation shown here (casting the handle), the 05 indicates
the operation number. Usually, 05 is the first operation of each
part. The 500 is the pieces per hour standard. This operator should
produce 500 pieces per hour. The 2.0 is the hours required to
produce 1,000 pieces. At 500 pieces per hour, it would take us 2
hours to make 1,000. How many people would be required to cast 2,000
handles per shift?
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Not many people, departments, or plants work at 100% performance.
How many hours would be required if we work at the rate of
60%, 85%, or 120%?
4 hours
4 hours
4 hours
----------- = 6.66 hours;
------------- = 4.7 hours;
-------------- = 3.33 hours.
60%
85%
120%
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Look again it use operations chart shown in Figure 4-1. Note the
total 138.94 hours at the bottom right side. The operations chart
includes every operation required to fabricate, paint, inspect,
assemble, and pack out a product. The total hours is the total time
required to make 1,000 finished products.
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In our water valve factory, we need 138.94 hours at 100% to produce
1,000 water valves. If this is a new product, we could expect 75%
performance during the first year of production. Therefore,
138.94 hours per
1,000
---------------------------------- = 185 hours/1,000
where 75% = 0.75
75% performance
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The marketing department has forecasted sales of 2,500 water valves
per day. How many people are needed to make water valves?
185 hours/1,000 X 2.5 (1,000) = 463 hours/day needed.
463 / 8 = 57.87
which is equal to 58 people.
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Management will be judged by how well it performs to this goal.
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If less than 2,500 units are produced per day with the 58 people,
management will be over budget, and that is not good.
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If it produces more than 2,500 units per day, management is judged
as being good at managing, and the managers are promotable.
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For example, how many direct labor employees do we need for a
multi-product plant? Per day, 1,132 hours of direct labor are
needed. Each employee will work 8 hours; therefore,
1,132 hours
----------------------- = 141.5 employees.
8 hours/employee
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We will hire 142 employees, and management will be evaluated on the
performance of these 142 employees. Without time standards, how many
employees would you hire?
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