work measurement ppt @ bec doms
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Work Measurement
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Outline LABOR STANDARDS AND WORK MEASUREMENT HISTORICAL EXPERIENCE TIME-STUDIES PREDETERMINED TIME STANDARDS WORK SAMPLING
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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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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
Uses of Labor Standards
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Historical experience Time studies Predetermined time
standards (MTM) Work sampling
© 1995 Corel Corp.
Sources of Labor Standards
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Historical Experience
Relatively easy, convenient, and inexpensive Not objective, unknown accuracy
Not recommended
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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 Studies
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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 times
adjusted for unusual influences)
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6. 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 Time Study - continued
Standard time = Total normal time1- Allowance factor
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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.
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Rest Allowances (%) for Various Classes of Work
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, pushingWeight lifted (pounds)20 …………………………………40………………………………….60………………………………….
5 4
2
2
7
3 917
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Rest Allowances (%) for Various Classes of Work - Continue
(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
2 5
1-10
2 5
2 5
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Rest Allowances (%) for Various Classes of Work - Continue
(H) Mental strain(i) Complex or wide span of attention
………………………(ii) Very complex …………….
(I) Tediousness(i) Tedious …………………….(ii) Very tedious ………………
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2 5
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Time 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
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2
n
xixs :Note
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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?
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Common z values
Desired ConfidenceLevel (%)
Z Value
90.11 1.65
95.00 1.96
95.45 2.00
99.11 2.58
99.73 3.0099.0
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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 Equations
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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 Standards
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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 Motion
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Sample MTM Table for GET and PLACE Motions
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MTM-HC Analysis: Pouring Tube Specimen
Element Description Element TimeGet tube from rack AA2 35Get stopper, place on counter
AA2 35
Get centrifuge tube, place at sample tube
AD2 45
Pour (3 sec.) PT 83Place tubes in rack (simo) PC2 400.0006*238=Total standard minutes = 0.14
Total TMU
238
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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 Sampling
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Used for Ratio delay studies Setting labor standards Measuring worker performance
Work Sampling
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The Five Step Work Sampling Procedure
1. Take a preliminary sample to obtain an estimate of the parameter value
2. Compute the sample size required3. Prepare a schedule for observing the worker at
appropriate times4. Observe and record worker activities; rate worker
performance5. Determine how workers spend their time (usually as a
percent)
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Work 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
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Normal Time =(Total Time) (% of time working) (Rating)
Number of units Produced
Standard Time = Normal Time
1 - Allowance
Work Sampling Equations
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Work Sampling Time Studies
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