Time and motion study

Operations Management Work Measurement Supplement 10 PowerPoint presentation to accompany Operations Management, 6E (Heizer & Render)

S10-1

© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458

Outline ♦ Labor Standards and Work Measurement ♦ Historical Experience ♦ Time-Studies ♦ Predetermined Time Standards ♦ Work Sampling

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S10-2

© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458

Learning 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

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S10-3

© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458

Uses of Labor Standards ♦ 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

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S10-4

© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458

Sources of Labor Standards ♦ Historical experience ♦ Time studies ♦ Predetermined time standards (MTM) ♦ Work sampling © 1995 Corel Corp.

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S10-5

© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458

Time Studies ♦ 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

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S10-6

© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458

The Eight Steps to Conducting a Time Study ➊ Define the task to be studied (after a methods analysis) ➋ Break down the task into precise elements ➌ Decide how many times each element of the task must be measured ➍ Record the times and ratings of performance for the task elements ➎ Compute the average observed cycle time (element times adjusted for unusual influences)

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S10-7

© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458

The Eight Steps to Conducting a Time Study - continued ➏ Compute the normal time for each task element: Normal time = (Average actual cycle time) x (Rating factor) ➐ Sum the normal times for each element to develop total normal Total time Standard time =a normal time for the task1- Allowance factor ➑ Compute the standard time: PowerPoint presentation to accompany Operations Management, 6E (Heizer & Render)

S10-8

© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458

Allowances ♦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)

S10-9

© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458

Time Studies - Sample Size zs   Sample size, n =    hx 

2

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 2 ( ) x − x ∑ i sample Note : s = x = mean of the initial sample PowerPoint presentation to accompany Operations Management, 6E (Heizer & Render)

S10-10

n −1

© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458

Considerations in Determining Sample Size ❶ How accurate do you want to be? ❷ What level of confidence do you want your measurements to have? ❸ How much variation exists within the job elements? PowerPoint presentation to accompany Operations Management, 6E (Heizer & Render)

S10-11

© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458

Common 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)

S10-12

© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458

Time Study Equations Allowance factor

Nonwork time = Total time

Σ Element times Average element time = Number of cycles

= Normal timeAverage element time * Perf. Rat Total normal time Standard time = 1 - Allowance factor PowerPoint presentation to accompany Operations Management, 6E (Heizer & Render)

S10-13

© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458

Predetermined Time Standards ♦ 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

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S10-14

© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458

MTM Table for Reach Motion Hand in

Time TMU

Motion

Distance Moved (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. 1 TMU = . B Reach to object in variable 0006 locations. minutes C Reach to object jumbled© with 2001 by Prentice Hall, Inc., Upper Saddle PowerPoint presentation to accompany S10-15 River, N.J. 07458 Operationsothers. Management, 6E (Heizer & Render)

Sample MTM Table for GET and PLACE Motions

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S10-16

© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458

Work Sampling ♦ 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

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S10-17

© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458

Work Sampling ♦ Used for ♦ ♦ ♦

Ratio delay studies Setting labor standards Measuring worker performance

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S10-18

© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458

The Seven Step Work Sampling Procedure ➊ Take a preliminary sample to obtain an estimate of the parameter value ➋ Compute the sample size required ➌ Prepare a schedule for observing the worker at appropriate times ➍ Observe and record worker activities; rate worker performance

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S10-19

© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458

The Seven Step Work Sampling Procedure continued ➎ Record the number of units produced during the applicable portion of the study ➏ Compute the normal time per part ➐ Compute the standard time per part

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S10-20

© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458

Work Sampling Sample Size z 2 p( 1 − p ) n= h2 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)

S10-21

© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458

Work Sampling Equations

(Total Time) (% of time working) (Rating) Normal Time = Number of units Produced Normal Time

Standard Time =

1 - Allowance

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S10-22

© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458

Figure S10.3

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S10-23

© 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458