powerpoint presentation to accompany operations management, 6e (heizer & render) © 2001 by...
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PowerPoint presentation to accompany Operations Management, 6E (Heizer & Render)
© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458S10-1
Operations Operations ManagementManagement
Work MeasurementWork MeasurementSupplement 10Supplement 10
PowerPoint presentation to accompany Operations Management, 6E (Heizer & Render)
© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458S10-2
OutlineOutline
Labor Standards and Work Measurement Historical Experience Time-Studies Predetermined Time Standards Work Sampling
PowerPoint presentation to accompany Operations Management, 6E (Heizer & Render)
© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458S10-3
Learning ObjectivesLearning Objectives
When you complete this supplement, you should be able to :
Identify or Define: Four ways of establishing labor standards
Describe or Explain: Requirements for good labor standards Time study Predetermined time standards Work sampling
PowerPoint presentation to accompany Operations Management, 6E (Heizer & Render)
© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458S10-4
Costing labor content of products Planning staffing needs Estimating time and cost for bids Planning production (crew size and work
balance) Basing wage-incentive plans Determining employee efficiency
Uses of Labor StandardsUses of Labor Standards
PowerPoint presentation to accompany Operations Management, 6E (Heizer & Render)
© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458S10-5
Historical experience Time studies Predetermined time
standards (MTM) Work sampling
© 1995 Corel Corp.
Sources of Labor StandardsSources of Labor Standards
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Labor standards are based on observing worker doing task Observe only a sample of work Use average time & pace to set standard
Disadvantages Requires a trained & experienced analyst Standard cannot be set before task is performed
Time StudiesTime Studies
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© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458S10-7
The Eight Steps to Conducting a The Eight Steps to Conducting a Time StudyTime Study
Define the task to be studied (after a methods analysis)
Break down the task into precise elements Decide how many times each element of the
task must be measured Record the times and ratings of
performance for the task elements Compute the average observed cycle time
(element times adjusted for unusual influences)
PowerPoint presentation to accompany Operations Management, 6E (Heizer & Render)
© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458S10-8
Compute the normal time for each task element:Normal time = (Average actual cycle
time) x (Rating factor) Sum the normal times for each element to develop
a total normal time for the task Compute the standard time:
The Eight Steps to Conducting a The Eight Steps to Conducting a Time Study - continuedTime Study - continued
Standard time = Total normal time1- Allowance factor
PowerPoint presentation to accompany Operations Management, 6E (Heizer & Render)
© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458S10-9
AllowancesAllowances
Personal time allowance - 4% - 7% of total time - use of restroom, water fountain, etc.
Delay allowance - based upon actual delays that occur
Fatigue allowance - to compensate for physical or mental strain, noise level, tediousness, heat and humidity, assumption of an abnormal position, etc.
PowerPoint presentation to accompany Operations Management, 6E (Heizer & Render)
© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458S10-10
Time Studies - Sample SizeTime Studies - Sample Size
xhzs
n ,size Sample
h = accuracy level desired as percent of job element, expressed as a decimal (5% = 0.05)
z = number of standard deviations required for the desired level of confidence
s = standard deviation of the initial sample
x = mean of the initial sample
nxx
s :Note i
PowerPoint presentation to accompany Operations Management, 6E (Heizer & Render)
© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458S10-11
Considerations in Determining Considerations in Determining Sample SizeSample Size
How accurate do you want to be? What level of confidence do you want your
measurements to have? How much variation exists within the job
elements?
PowerPoint presentation to accompany Operations Management, 6E (Heizer & Render)
© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458S10-12
Common z valuesCommon z values
Desired Confidence Level (%)
Z Value
90.0 1.65
95.0 1.96
95.4 2.00
99.0 2.58
99.7 3.00 99.0
PowerPoint presentation to accompany Operations Management, 6E (Heizer & Render)
© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458S10-13
Allowance factor Nonwork timeTotal time
Average element time Element times
Number of cycles
Normal time Average element time * Perf. Rating
Standard timeTotal normal time
1 - Allowance factor
=
=
=
=
Time Study EquationsTime Study Equations
PowerPoint presentation to accompany Operations Management, 6E (Heizer & Render)
© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458S10-14
Labor standards are set from times in published tables (e.g., MTM Table)
Procedure Divide manual work into basic elements Look up basic element times in table; sum
Advantages Times established in laboratory setting Useful for planning tasks Widely accepted by unions
Predetermined Time StandardsPredetermined Time Standards
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© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458S10-15
Time TMU Hand inMotion
DistanceMoved (in)
A B C A B
3/4 or less 2.0 2.0 2.0 1.6 1.6
1 2.5 2.5 3.6 2.3 2.3
2 4.0 4.0 5.9 3.5 2.7
A Reach to object in fixed location. B Reach to object in variable locations.C Reach to object jumbled with others.
1 TMU = .0006 minutes
MTM Table for Reach MotionMTM Table for Reach Motion
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Sample MTM Table for GET and Sample MTM Table for GET and PLACE MotionsPLACE Motions
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Labor standard is set using output and % of time worker spends on tasks
Involves observing worker at random times over a long period
Advantages Less expensive than time studies Observer requires little training
Disadvantages Ineffective with short cycles
Work SamplingWork Sampling
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Used for Ratio delay studies Setting labor standards Measuring worker performance
Work SamplingWork Sampling
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© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458S10-19
The Seven StepThe Seven Step Work Sampling Procedure Work Sampling Procedure
Take a preliminary sample to obtain an estimate of the parameter value
Compute the sample size required Prepare a schedule for observing the
worker at appropriate times Observe and record worker activities; rate
worker performance
PowerPoint presentation to accompany Operations Management, 6E (Heizer & Render)
© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458S10-20
The Seven StepThe Seven Step Work Sampling Procedure - continuedWork Sampling Procedure - continued
Record the number of units produced during the applicable portion of the study
Compute the normal time per part Compute the standard time per part
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© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458S10-21
Work Sampling - Sample SizeWork Sampling - Sample Size
h
ppzn
p = estimated value of sample proportion (of time worker is observed busy or idle)
h = accuracy level desired in percent, expressed as a decimal
PowerPoint presentation to accompany Operations Management, 6E (Heizer & Render)
© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458S10-22
Normal Time =(Total Time) (% of time working) (Rating)
Number of units Produced
Standard Time = Normal Time
1 - Allowance
Work Sampling EquationsWork Sampling Equations
PowerPoint presentation to accompany Operations Management, 6E (Heizer & Render)
© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458S10-23
Figure S10.3Figure S10.3