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Operations Management Work Measurement Supplement 10. Outline. LABOR STANDARDS AND WORK MEASUREMENT HISTORICAL EXPERIENCE TIME-STUDIES PREDETERMINED TIME STANDARDS WORK SAMPLING. Learning Objectives. When you complete this supplement, you should be able to : Identify or Define :
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Operations ManagementWork MeasurementSupplement 10 © 2004 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 © 2004 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 © 2004 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) • Estimating expected production • Basing wage-incentive plans • Determining employee efficiency © 2004 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. © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458
Historical Experience • Relatively easy, convenient, and inexpensive • Not objective, unknown accuracy Not recommended © 2004 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 © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458
The Eight Steps to Conducting a Time 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 timesadjusted for unusual influences) © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458
Total normal time 1- Allowance factor Standard time = The Eight Steps to Conducting a Time Study - continued • Compute the normal time for each task element: Normal time = (Average actual cycletime) x (Rating factor) • Sum the normal times for each element to develop a total normal time for the task • Compute the standard time: © 2004 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. © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458
Rest Allowances (%) for Various Classes of Work 5 4 2 2 7 3 9 17 1. Constant allowance (a) Personal allowance ……………... (b) Basic fatigue allowance ………… 2.Variable allowances: (A) Standing allowance …………….. (B) Abnormal position (I) Awkward (bending) …………. (ii) Very awkward (lying, stretching) …………………….. (C) Use of force or muscular energy in lifting, pulling, pushing Weight lifted (pounds) 20 ………………………………… 40…………………………………. 60…………………………………. © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458
Rest Allowances (%) for Various Classes of Work - Continue 2 5 1-10 2 5 2 5 (D) Bad light (i) Well below recommended ….. (ii) Quite inadequate ……………. (E) Atmospheric conditions (heat and humidity) Variable ………………………….. (F) Close attention (i) Fine or exacting ……………… (ii)Very fine or very exacting …... (G) Noise level (i) Intermittent – loud …………… (ii) Intermittent – very loud or high-pitched © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458
Rest Allowances (%) for Various Classes of Work - Continue 4 4 2 5 (H) Mental strain (i) Complex or wide span of attention ……………………… (ii) Very complex ……………. (I) Tediousness (i) Tedious ……………………. (ii) Very tedious ……………… © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458
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 Time Studies - Sample Size © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458
Considerations in Determining Sample 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? © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458
Desired Confidence Z Value Level (%) 90.11 1.65 95.00 1.96 95.45 2.00 99.11 2.58 99.73 3.00 99.0 Common z values © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458
Time Study Equations Nonwork time = Allowance factor Total time Element times Average element time = Number of cycles = Normal time Average element time * Perf. Rating Total normal time = Standard time 1 - Allowance factor © 2004 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 © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458
MTM Table for Reach Motion Hand in Time TMU Motion Distance A B C A B Moved (in) 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 © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458
Sample MTM Table for GET and PLACE Motions © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458
MTM-HC Analysis: Pouring Tube Specimen © 2004 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 © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458
Work Sampling • Used for • Ratio delay studies • Setting labor standards • Measuring worker performance © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458
The Five Step 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 • Determine how workers spend their time (usually as a percent) © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458
Work Sampling - Sample Size p = estimated value of sample proportion (of time worker is observed busy or idle) h = accuracy level desired in percent, expressed as a decimal © 2004 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 © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458
Work Sampling Time Studies © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458