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4. Time Study

The major objective of this chapter is to learn how to calculate a time standard based on stopwatch time study procedures.

Konsep Pengukuran Sistem Kerja

Suatu siklusPerancangan Sistem KerjaPengukuran (Sistem) KerjaPembakuan Sistem Kerja (Standarisasi)

Pengukuran: ???

Time StudyA process for measuring the required time for performing a given task, by a given method, by a trained worker, working in a normal pace.

Why needed?For methods improvement

For determining time standards

Needs for Time Standard

Developing schedulesDetermining wage payment plansEstimating production costsProviding a base for estimating productivity goalsAppraising employee performanceEvaluating alternative process, equipment

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Methods for Creating Time Standards

Direct time studyCyclic workNon cyclic work

Work samplingSynthetic data

Predetermined times

Direct Time Study - Tools

HOW ??? Direct Time Study

Methods improvementSelection of the examined workersExplanation (union, managers, workers)Collecting and recording informationTask division into elements

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Methodology

Who to choose?Select an Average Worker (What is average?)Experienced operatorNormal pace

Consistency (well defined, understood by all)No undue strain for entire day (speed/effort)Pace that should be performed, not average of current rate

Rating accuracy Worker acceptance

Can you suggest a better method?

Preparation for Timing

Identify the TASK/ CYCLE to be studied before time study Analyze the Complete Task

MethodLayout of workplaceEquipment usedEnvironmental conditionsMachine speeds and feedsInspection equipment

Communications with foreman, workersDocuments for process, task instructionsEstablish relationship

Elemental analysisBreak task into elements

Fundamental definitions

What is an ELEMENT?Element is a component of job or task that are logical divisions with easily identifiable starting and end points, and are repeated on a regular basis

What is a CYCLE?Cycle is the completion of the activities (elements) required to perform the job under study.

Element Analysis

Every element must have an easily identifiable starting and ending point (breakpoints)No discontinuities between elementsElements times: 0.04min (short), 0.25min (reasonable)Relative frequency must be included

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WaktuSiklus

WaktuNormal

WaktuBaku

P l

Determining Number of Cycles

Time measurementMeasuring time of each elementThe number of observation of each element depends on the significance level and required level of accuracy

Primary time study(normally 5 to 10

observation)

Examination of therequired number of

observations (N)

Continue study up to Nobservations

Re-checking the requirednumber of observations (n)

N>=n

End the time study

N=n

No

Yes

Recommended number of cycles/observations

Maytag Company Approach

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r Rules for Performing Time Study

Don’t comment to the worker during the taskStand (don’t sit) beside the workerWrite every event (even though it may seems not important)Have a good position to observeStop the study if the worker seems to be under pressure and it affects his/her work

Time Study On Cyclic Work

Rating evaluation may be written once in a couple of cyclesElements times: 0.04min (short), 0.25min (reasonable)Denoting non-cyclic elementsThe breakpoint between elements should be clear (touch, push, etc.).

Types of Elements

Manual/machine (determines the task duration)Cyclic/non cyclicFixed time/ variable time (i.e. loading time as a function of weight)Avoidable/unavoidable unproductive elements (sometimes hard to identify)

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Time Study on Non Cyclic Work

Use continuous timing Divide the task into relatively large elementsWrite the evaluated performance rate at the end of each elementMultiply the observed time with the rate and summarize the data

Principles of the learning curve

A learning curve identifies the relationship between experience and performance to estimate/forecast future performance

Each time you perform a task it takes less time than the last

The extent of task time decreases over time

The reduction in time will follow a predictable pattern

x

Learning curve graph

Cyc

le ti

me

(min

)

Number of cycles

x RATING FACTORS

WaktuSiklus

WaktuNormal

WaktuBaku

P l

x

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What happens when standards are not accurate?

Too tight (standard time is too short)

Too loose (standard time is too long)

Do we expect the average worker to work in normal rating ?

Performance Ratings

The pace of work changesBetween workersWithin the same worker throughout the day

Analysts must be consistent in rating performancePerformance is influenced by speed and methods

Rating Evaluation Methods

Subjective judgmentPractice by watching moviesFor a study with long elements, rate each separatelyMethods:

Speed ratingWestinghouse

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Subjective performance ratings

Analyst uses own judgment from experience

When would these ratings become a problem?

Consistency is most important!

Subjective ratings: Simple guide

035526987104

023456

No activityVery slow, clumsySteady, deliberateBrisk, businesslikeVery fast, high degree of dexterityUpper limit for short period

067

100133167200

Cards Dealt per½ Minute

Walking Speed (mph)

Verbal Anchor PointsRating

Criteria for Successful Speed Rating Evaluation

Experience in the class of work performedSelection of an operator who gives performances between 85 and 115Use of the average value of three or more independent studies

Westinghouse Rating System

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Westinghouse example

An operator is rated as working with excellent skill and good effort, under fair conditions and average consistency. What is the operator’s performance rating?

S = 0.11E = 0.05Cd = -0.03Cs = 0.00Wn = 16.95 (Silvi)

Case study

Allowances (PFD)

Allowances = Additional time added to the normal time for creating the standard time

Personal needsFatigueDelays (unavoidable)

How can we determine PFD allowances?

Direct time study – observers (analysts) study several workers for a long period of time

Work sampling studies – large number of observations at random times to mark activity of worker

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Elements of Allowances

Normal Time

Extra Allowances

Unavoidable Delays

Special AllowancesConstant Allowances

Basic Fatigue

Personal Need

Variable Fatigue

Avoidable Delays

Standard Time

Total Allowances Allowances + =

Constant Allowances

Personal needs – water fountain, restroom, etc. (may depend on working condition)

About 5%

Basic fatigue – Assumes worker doing light job in very good environmental and working conditions.

About 4%

9% total constant allowances

Variable fatigue

Additional fatigue caused byWorking conditions (noise, heat, humidity)Nature of work (posture, muscular exertion, tediousness, mental stress)

Special Allowances

Unavoidable delaysSupervisor interruptionsMaterial irregularitiesStochastic behavior in production (machine interference – maintenance workers)

Avoidable delays (idleness, social visits)

Extra Allowances (learning time, etc.)

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Practices

Chapter 11, Problem no 1“Develop an allowance factor for an assembly element for which the operator stands in a slightly awkward position, regularly lifts a weight of 15 pounds, and has good light and atmospheric conditions. The attention required is fine, the noise level is continuous at 70dBA, and the mental strain is low, as is the monotony and the tediousness of work”.

Summary: Ratings and Allowances

Accurate standards are necessary for both workers and managementPerformance ratings are included in normal timesAllowances are added to normal times for standard timesPerformance ratings can be obtained by

Subjective ratingsSystems such as WestinghouseSynthetic ratingsObjective measurements

Allowances account for constant and variable PFD measures