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Chapter 24: Determining Time/Job. Uses for time/unit information Cost allocation Production and inventory control Evaluation of alternatives Determining acceptable day’s work Determining incentive pay. Establishing time standards. Choice of time measurement technique depends on: - PowerPoint PPT Presentation
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Chapter 24: Determining Time/Job
Uses for time/unit information Cost allocation Production and inventory control Evaluation of alternatives Determining acceptable day’s
work Determining incentive pay
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Establishing time standards
Choice of time measurement technique depends on: Cost of obtaining the information Benefits of using the information Inaccurate information leads to wrong decisions. If the standard is set 5% too low, there is a 5% loss
in productivity.
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Nonengineered (type 2) estimates
“Did take” or “Should take” Used as a temporary measure, based on
Historical records Expert opinion Time logs Occurrence sampling
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Engineered (type 1) estimates
Provide accurate estimates Must be preceded by a methods and quality
analysis Have few subjective and many objective
characteristics May be found through stopwatch time study or
standard data
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Time study: 3 levels Observed time: “raw” data Normal time = Observed time × Rating
Rating:
Standard time = Normal time + Allowances Standard time is normal time plus allowances.
Shift allowances are a percentage of shift time. Work allowances are a percentage of work time.
Personal Allowances
Fatigue Allowances
Delay Allowances
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Standard data
Are expressed in normal time
Are set by analyst visualizing the work method
Have three advantages: Cost of determining the standard is low. Consistency is high. Standards can be calculated ahead of production.
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Learning
Amount of time to perform a task depends on how much practice the person has.
Learning occurs in both the individual and the organization.
The primary cause for incorrect standard times is failure to adjust for learning.
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Individual learning
Improvement in time/unit even though the product, tools, and equipment don’t change.
Individual improvements come from: Better eye–hand coordination Fewer mistakes Reduced decision time
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Organizational learning
Improvement in time/unit due to changing product design, changing tools and equipment, or changing work methods.
Organizational learning includes individual learning.
Organization improvements come from: Operator learning New technology Substitution of capital for labor
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Quantifying improvement Manufacturing progress curves are placed on a
log–log scale. On a log scale the physical distance between doubled
quantities is a constant. The progress curve becomes straight.
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Example learning curve
Assembling a part
This is an ____________ learning curve.
Mathematically, ______________
# CyclesLog # Cycles
Cycle Time, min.
Log Cycle Time
% Decrease
1 0 12.00 1.08 20
2 0.301 9.60 .982 20
4 0.602 7.68 .885 20
8 0.903 6.14 .788 20
16 1.204 4.92 .692 20
32 1.505 3.93 .594 20
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Working with the curve
Determining the learning factor, b, for the 80% curvelog10 y = log10a + b*log10x
or, rearranging and solving for b:
Solve for a using the cycle time for 1 cycle
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Using the learning curve
1. MTM-2 analysis shows a standard time of 2 min. How many cycles does it take to reach it?
2. How long will this take (in minutes)?
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Your turn …
You have conducted a time study for an operation. At the 50th cycle the cycle time is 20 minutes and at 100th cycle the cycle time is 15 min. (i.e.,
(x1,y1) = (50,20) and (x2,y2) = (100,15))
1. What is the learning curve? What are a and b?
2. How many cycles would be required to meet a standard time of 10 minutes?
3. How long will this take? What is the average cycle time?
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Organization progress
Rate of improvement depends on amount that can be learned.
Amount that can be learned depends on: Amount of previous experience with the product Extent of mechanization
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Individual learning Has two components:
Cognitive learning Motor learning
Motor learning is slower. Cognitive learning has greater improvement.
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Applications of learning
Cost allocation
Scheduling
Evaluation of alternatives
Acceptable day’s work
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Documenting, using, and maintaining standards Quantification of output Audits Feeding information back to workers
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