Wrk Msrmt-1

8/8/2019 Wrk Msrmt-1

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Establishing the time taken by a worker to carry out a specified joba defined level of performance.

Purpose of Work Measurement :y To reduce the amount of ineffective time

y Provides management with a means of identifying the causes of ineffective time


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1 . Time study

2. Synthesis from standard data

3. Analytical estimating

4. Predetermined motion time systems

5. Activity sampling


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Select work elements

Timing the elements

Determine sample time

Setting the work standard


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O bvious starting and stopping points

Long enough to accurately time

Should have been running smoothly for a period of time in astandard work environment

Separate incidental operations from the repetetive work


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Stopwatch

Investigate single sample times that differ greatly from other

timings for the same element. Dont include irregularoccurrences', use allowances.


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We are trying to estimate the average of the true timedistribution to a certain precision with a particular confidence

Do a set of initial samples

Use

n = required sample size

p = precision of estimate as a proportion of true value

t = mean time from sample (the select time )

W = standard deviation of sample times

z = number of standard deviations for desired confidence

n = [( )( )] z W p t

2


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1.Time Study Method


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Step 1: Selecting Work ElementsStep 1: Selecting Work Elements

Work Element

1. Get cartons2. Put liner in carton3. Place cups in carton4. Seal carton and set aside


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Step 2: Timing the ElementsStep 2: Timing the Elements(10 observations)(10 observations)

Standard SelectDeviation, W Time, t

Work Element (minutes) (minutes)

1. Get cartons 0.0305 0.252. Put liner in carton 0.0171 0.113. Place cups in carton 0.0226 0.714. Seal carton and set aside 0.0241 1.10


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Step 3: Determining the Sample SizeStep 3: Determining the Sample Size

Standard Select RequiredDeviation, W Time, t Sample

Work Element (minutes) (minutes) Size1. Get two carton 0.0305 0.252. Put liner in carton 0.0171 0.113. Place cups in carton 0.0226 0.714. Seal carton and set aside 0.0241 1.10

DesiredConfidence (%) z

90 1.6595 1.9696 2.0597 2.1798 2.3399 2.58

1.96 W0.04 t n = [( )( )]

2


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Standard Select RequiredDeviation, W Time, t Sample

Work Element (minutes) (minutes) Size

1. Get carton 0.0305 0.252. Put liner in carton 0.0171 0.113. Place cups in carton 0.0226 0.714. Seal carton and set aside 0.0241 1.10

n = [( )( )]1.96 0.03050.04 0.252

n=36


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Standard Select Required

Deviation, W Time, t SampleWork Element (minutes) (minutes) Size

1. Get carton 0.0305 0.25 362. Put liner in carton 0.0171 0.11 583. Place cups in carton 0.0226 0.71 3

4. Seal carton and set aside 0.0241 1.10 2


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N eed to judge the pace of the worker to produce a rating factor(RF).

x RF < 1 means worker going slower than standardx RF > 1 means worker going faster than standard

AllowancesContingency Allowance. For legitimate and expected work or delays

which are uneconomic to measureRelaxation Allowance. To allow for physiological or psychologicaleffects of conditions eg.

5-7% Personal0- 1 0% Energy O utput0-5% N oisy0- 1 00% Conditions


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Basic time ( BT) in Basic Minutes ( BM) is

O bserved Time * Rating Factor

Basic Time for Cycle ( BTC) is7 BT

Standard time is

BTC + AllowancesST = BTC (1 + A )

BT = t * RF BTC = 7 BT


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Step 4: Setting the StandardStep 4: Setting the Standard(after 48 additional observations)(after 48 additional observations)

Work Element t RF BT

1. Get carton 0.26 1.052. Put liner in carton 0.10 0.953. Place cups in carton 0.75 1.104. Seal carton and set aside 1.08 0.90

BT = t * RF


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Work Elementt

RF BT1. Get carton 0.26 1.05 0.282. Put liner in carton 0.10 0.953. Place cups in carton 0.75 1.104. Seal carton and set aside 1.08 0.90

BT = 0.26 * 1.05 =0.28 minute


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1. Get carton 0.53 1.05 0.282. Put liner in carton 0.10 0.95 0.103. Place cups in carton 0.75 1.10 0.834. Seal carton and set aside 1.08 0.90 0.97

Total 2.18

BT = t * RF BTC = 7 BT


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Allowance ( A ) = 15% Total 2.18

ST = BTC (1 + A ) ST = BTC (1 + A )


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Allowance ( A ) = 15% Total 2.18Standard Time 2.51

ST = 2.18 (1 + 0.15) = 2.51 minutes/carton


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Synthesis is a Work Measurement technique which builds upStandard Times using data obtained from previous Time Studies

Build up job times from previous element times from studies onother jobs

Useful where new jobs made up of well understood elements

Estimating in connection with quotations


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Times built up from synthetic data fall into two main categories:

Element Times which can be assembled to form job times, used where accuracy equal to that of time study is required;

Job Cycle Times where such accuracy is not needed, i.e. painting,maintenance work


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The various steps involved are :1 . Find out the job details2. Break the job into its elements.3. Select time values

4. Estimate the time values5. Add the time values6. Add the appropriate blanket relaxation allowance (say 1 0% to

20% of total normal or basic time)7. Add any other allowances if applicable, to arrive at the standard

time for the given job.


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Use established timings for basic human movements to build uptime for jobPotentially accurate

Can be used before production in place

Performance ratings may not be required

Time consuming

Cant use for low repeatability jobs

Different part shapes


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Types of PMTS :MTM x Predetermines time values for basic motions .

Work Factorx Based on basic motions which are modified elements of difficulty, which tend

to make slower movement.

Basic Motion Times( BMT)x Times were derived and carefully checked agains a variety of factory

operations before being accepted for general use.


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Advantages :Fine analysisFaster and economical than time studyN o interference in the normal work routineEffective tool for repetitive jobs of short duration

Disadvantages:Standards are not available for each human activity

Limited to only uninhibited workThis technique is to be performed under expert guidance


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A large number of instantaneous observations made over a lengthof time

Percentage of observations in which an activity is taking placeapproximates proportion of total time that activity takes place

P= x / N


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y AdvantagesCan measure activities which are too impracticalor costly to measure by time study

O nly needs one observerSampling can be interrupted

y DisadvantagesQ uicker and easier to use Work Study on jobs of short durationDoes not provide elemental detail


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Confidence interval

Probability that trueproportion will fall

within confidence interval

p - e p + e p

e = z p (1 - p )

n


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