Time and motion study

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



OutlineOutline

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



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



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



Historical experience Time studies Predetermined time

standards (MTM) Work sampling

© 1995 Corel Corp.

Sources of Labor StandardsSources of Labor Standards



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



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 elementsDecide how many times each element of the

task must be measuredRecord the times and ratings of

performance for the task elementsCompute the average observed cycle time

(element times adjusted for unusual influences)



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 taskCompute 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



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.



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



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?



Common z valuesCommon z values

Desired ConfidenceLevel (%)

Z Value

90.0 1.65

95.0 1.96

95.4 2.00

99.0 2.58

99.7 3.0099.0



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



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



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



Sample MTM Table for GET and Sample MTM Table for GET and PLACE MotionsPLACE Motions



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



Used for Ratio delay studies Setting labor standards Measuring worker performance

Work SamplingWork Sampling



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 requiredPrepare a schedule for observing the

worker at appropriate timesObserve and record worker activities; rate

worker performance



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 partCompute the standard time per part



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



Normal Time =(Total Time) (% of time working) (Rating)

Number of units Produced

Standard Time = Normal Time

1 - Allowance

Work Sampling EquationsWork Sampling Equations



Figure S10.3Figure S10.3

Documents

Time and motion study