Basics of Work Study - Work Measurement

N.K.Agarwal

Work Study

• Systematic examination of the method of carrying out an activity so as to – Improve the existing method of doing the

job, called method study, and– To set up standards of performance ,

called work measurement

With the objective of improving the productivity

Work Study - Objectives

• To recommend and implement the desired improvement in work methods by establishing the most economical way of doing things

• Investigation and analysis of existing situation• Examination of weaknesses if any in the production

process• Most effective use of the existing or proposed plant• Efficient use of human efforts• Ensure proper performance of those employed in the

production process

• Measurement of work values• To initiate and maintain incentive bonus schemes• Setting standards for labor cost and originating labour

cost control documentation• To standardise the method, material and equipment

used in the production process• To determine the time required by an ideal operator

to perform the task at some desired level of performance

Work Study - Objectives

BASIC WORK CONTENT

POOR DESIGN AND FREQUENT CHANGES

WASTE OF MATERIALS

POOR LAYOUT AND UTILISATION OF SPACE

INADEQUATE MATERIAL HANDLING

FREQUENT STOPPAGES AS PRODUCTION CHANGES FROM ONE PRODUCT TO ANOTHER

INEFFECTIVE METHOD OF WORK

POOR PLANNING OF INVENTORY

FREQUENT BREAKDOWNS OF MACHINES AND EQUIPMENT

ABSENTEEISM AND LATENESS

POOR WORKMANSHIP

ACCIDENTS AND OCCUPATIONAL HAZARDS

TOTAL WORK CONTENT

WORK CONTENT ADDED DUE TO POOR PRODUCT DESIGN OR MATERIAL SPECIFICATION

WORK CONTENT ADDED DUE TO INEFFICIENT METHODS OF MANUFACTURE OR OPERATION

WORK CONTENT ADDED DUE TO HUMAN FACTORS

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WORK STUDY

METHOD STUDY WORK MEASUREMENT

TO IMPROVE METHODS OF PRODUCTION

TO ASSESS EFFECTIVENESS OF WORKERS

RESULTING IN MORE EFFECTIVE USE OF MATERIALS, MANPOWER, PLANT & EQUIPMENT

MAKING POSSIBLE IMPROVED PLANNING & CONTROL, MANNING & AS A BASIS FOR SOUND INCENTIVES

HIGHER PRODUCTIVITY

WORK STUDY

Method Study

• Systematic investigation i.e. recording & critical examination of the existing method of doing a job in order to– Develop and install an easy, rapid,

efficient, effective & less fatiguing procedure

– Develop a more economic method

For doing the same job

Work Measurement

• Application of different techniques to measure and establish time required to complete the job by a qualified worker at a defined level of performance

• Objectives– Reveals excess work content in any operation– Can be used to look into cause and take steps to

reduce ineffective time– Set standard time for the work

Method Study - Procedure• Select and define

– Economic (cost) benefit is the main criteria

• Record– Recording/ collection of necessary information

• Movement of equipment or material

• Clerical procedure involved in the job

• Work done by an operator

• Movement of operator with respect to machines and other operations, etc.

• Examine critically the existing method– Each activity critically examined after recording all

relevant information about the same (for value / non value adding )

– Two sets of detailed questions are asked• To indicate facts and the reasons underlying• To indicate alternatives and means of

improvements– Brain storming and creative thinking session

• . Develop and evaluate the best method– Record method proposed– Consult management & workers for their

suggestions– Workout cost of installing new method– Prepare new flow process chart– Put up report for management approval

Method Study - Procedure

• Define the new method– Management and workers to be familiarised with the

new method and written standard practice report prepared

• Install– Properly plan and implement the new method– Do trial runs to remove snags till it works smoothly

• Maintain– Once installed, the new method to be maintained – Verify proper functioning through periodic checks /

verifications

Method Study - Procedure

Method Study - Techniques

• Various techniques used are– Charts

• Outline process charts• Flow process charts: man, material, equipment types• Two handed process charts• Multiple activity chart• Travel chart

OPERATION

STORAGE

DELAY OR TEMPORARY STORAGE

TRANSPORT

INSPECTION

OPERATION CUM TRANSPORT

OPERATION CUM INSPECTION

A chart / diagram giving an overall view of the process : activities represented by symbols

PROCESS CHARTS

– Diagrams• Flow • String• Cyclegraph• Chronocycle graph

– String diagram• String strung to follow path taken by material• Deals to solve complex movement & plant layout

Method Study - Procedure

– Cycle graph• Introduced by Gilberth• Photographic method • Very accurate• Used for recording very fast movement not possible for seeing by

eye

– Chronocycle graph• Light source 10-20 times per second records the path of movement

in the form of pear shaped spots on the plate

– Motion and film analysis( micro motion & memo motion studies)

• Simultaneous motion (Simo) chart• Pre-determined motion time system (PMTS)

Method Study - Procedure

– SIMO chart• Used for micro motion studies• Time in terms of winks • Very accurate for detailed analysis• 1 wink 1/2000 of a minute

Method study - Procedure

Work Measurement - Objectives

• Target time for each job can be estimated scientifically

• Sound comparison of alternative methods can be made by comparing their basic times

• Useful incentive schemes can be generated by linking these target times

• Variance between actual time and the target time can lead to apply better control on the operations

• It can lead to proper balancing of the work distribution• Forecast for future manpower and related costs can

be made

• Select the job to be measured– Decision mostly based on increasing productivity

• Break job into operations / elements• Determine number of observations to be

timed• Measure with a timing device and record on

time study form– Time study is a work measurement technique for

recording the times and rates of working for the elements of a specified job

• Compute Observed time

Work Measurement - Steps

• Calculate Normal (Basic) time by using Performance Rating Factor

• Add process allowance, rest and personal allowance and special allowances to Normal (Basic) time to obtain Standard time

• Define the new method• Install the new method as agreed standard

procedure with the standard time allowed• Maintain the new standard practice

Work Measurement - Steps

Time Estimates and Production Standards

• Standard Time– Time required to complete a unit of work

• Under existing working condition• Using specified method & machine• By an operator able to work in a proper manner

and at a standard pace

• Basic time– Time required to perform a task by a Normal

Operator working at a standard pace (rate) with no allowance for personal delays, unavoidable delays or fatigue

– Basic / Normal (time) = Observed time * Observed rating of operator / Standard rating ( i.e. 100 )

Time Estimates and Production Standards

• Allowances– Personal allowances

• For visiting toilets, drinking water etc

– Fatigue / relaxation allowance– Delay allowance

• For tool breakage, interruption by foreman etc

– Typically• Personal allowance : 2-5 % per day• Fatigue : 12-20% of normal time

Time Estimates and Production Standards

• Performance rating

– Indicates gauging and comparing the pace rate of the performance of a worker against a standard performance level set by time study engineer

– Rating Factor is the leveling factor– Generally 0-100 % standard rating scale is the

best and has been adopted by British Standard

Time Estimates and Production Standards

• Standard time calculation

– Standard time for an operation will be the sum of the standard times for all the elements of which it is made of.

– Expressed in standard minutes or hours

• Standard time = Basic time + Allowances– Basic (Normal time )= Observed time * Observed

rating of operator / Standard rating– Observed time is the time observed by stopwatch

Time Estimates and Production Standards

OBSERVED TIME

BASIC TIME

STANDARD TIME

RATING FACTORRELAXATION ALLOWANCE

DELAY ALLOWANCEINTERFERENCE ALLOWANCE

POLICY ALLOWANCE

BONUS

Performance Rating

ALLOWANCES

TIME ISSUED FOR PAYMENT PURPOSES

Work Measurement - Techniques

• Time study– Stop watch procedure

• Work sampling• Pre-determined Motion Time Systems (PMTS) or

Elemental Motion Time Systems ( EMTS ) or Basic Motion Time Systems (BMTS ) ( work factor and M-T-M systems )

• Structured estimation– Analytical estimation– Comparative estimations

Time Study - Procedure

• Most widely used and involves– Recording the time for performing a certain job / its

elements under specified conditions– Analyse data– Obtain time necessary for an operator for the job

at a defined performance rate

• Steps-preliminary– Identify job and operation to be timed– Use improved procedure– Select worker and brief him and his superior about

study– Collect equipments, arrange machine, jigs ,

fixtures etc

• Uniform & improved production flow• Higher productive efficiency• Reduced manufacturing cost• Fast & accurate delivery dates• Better employee-employer relations• Better service to customers• Job security & job satisfaction to workers• Better working & other conditions • Higher wages to workers

Work study- advantages

• Always looked upon by the supervisor & workers or unions with suspicion

• Sudden change is not appreciated

Work Study - Limitations

References

• Production Operations Management : Dr. B. S. Goel• Work Study (Motion & Time Study) : O.P.Khanna• Productivity Techniques : Gondhlekar / Salunke• Production and Operations Management :

Aswathappa / Bhat

Thank You

• TECHNIQUE IN WHICH – LARGE NUMBER OF OBSERVATIONS ARE

MADE OVER A PERIOD OF TIME OF ONE OR A GROUP OF MACHINES, PROCESSES OR WORKERS

– RECORD WHAT IS HAPPENING AT THAT INSTANT

• PERCENTAGE OF OBSERVATIONS RECORDED FOR A PARTICULAR ACTIVITY OR DELAY IS A MEASURE OF THE PERCENTAGE OF TIME DURING WHICH ACTIVITY OR DELAY OCCURS

WORK SAMPLING

PRE-DETERMINED MOTION TIME SYSTEM (PMTS)

• PRE-DETERMINED TIME STANDARD IS A WORK MEASUREMENT WHEREBY TIMES ESTABLISHED FOR BASIC HUMAN MOTIONS ( CLASSIFIED AS PER THE NATURE OF THE MOTIONS AND CONDITIONS UNDER WHICH THESE ARE MADE ) ARE USED TO BUILD UP THE TIME FOR THE JOB AT A DEFINED LEVEL OF PERFORMANCE ( B.S. 3138: 1969 )

• MACROMOTION TIME MEASURED IN SEVERAL SECONDS• MICRO MOTION –ELEMENTS OF THE JOB ARE BASIC

HUMAN MOTION WITH DURATION OF 0.1 SECONDS AND LESS

• OPERATIONS ARE RECORDED ON A MOVIE FILM

METHOD TIME MEASUREMENT (M-T-M )

• M-T-M ASSOCIATION GOT RECOGNITION IN 1948• BASIC HUMAN MOVEMENTS ARE ANALYSED IN

MORE DETAILS• TIME MEASURED IN TERMS OF TMUs (TIME

MEASUREMENT UNITS)• 1 TMU = 0.0006 MINUTES

STRUCTURED ESTIMATION

• A TECHNIQUE WHICH USES PAST DATA TO PREDICT FUTURE VALUES

• STEPS INVOLVED ARE:– BREAK THE JOB INTO ELEMENTS– USE STANDARD DATA TO GET TIME VALUES OF ELEMENTS

FOR WHICH SUCH INFORMATION IS AVAILABLE– MEASURE THE TIME VALUES OF ELEMENTS WHICH ARE

WORTH THE EFFORT

• TECHNIQUE IS A COMBINATION OF INFORMATION FROM STANDARD DATA, TIME STUDY AND ESTIMATION

• OVERALL TIME FOR THE JOB WILL BE WITHIN ACCEPTABLE LIMITS

STRUCTURED ESTIMATION

• COMPARATIVE ESTIMATION– RELIES ON IDENTIFICATION & MEASUREMENT OF

BENCHMARK JOBS OF KNOWN WORK CONTENT AGAINST WHICH ALL OTHER JOBS TO BE MEASURED ARE COMPARED

– STEPS INVOLVED ARE• BENCHMARK JOBS ARE SELECTED TO REPRESENT THE

WHOLE RANGE OF WORK INVOLVED AND TO REPRESENT INTERMEDIATE POINTS ON THE OVERALL SCALE OF THE JOB

• BENCHMARK POINTS ARE MEASURED WITH SOME PRECISION USING AN ESTABLISHED WORK MEASUREMENT TECHNIQUE

• IDENTIFY TIME BANDS OR SLOTS, DETERMINED BY STATISTICAL ANALYSIS WHICH MAY NOT BE OF EQUAL WIDTH, WITH EACH SLOT BEING ALLOCATED A BASIC OR STANDARD TIME EQUIVALENT TO ITS MID POINT

STRUCTURED ESTIMATION

• EACH OF THE BENCHMARK JOBS IS ASSIGNED TO THE APPROPRIATE SLOT

• WHEN ESTIMATING WORK SUBSEQUENTLY, THE ESTIMATOR REFERS TO THE BENCHMARK JOBS AND COMPARES THE JOB BEING MEASURED

• A COMPARISON OF THE WORK CONTENT OF THE JOB TO BE ESTIMATED WITH A NUMBER OF THE BENCHMARK JOBS

• ON BEING SATISFIED THAT THE CORRECT SLOT FOR THE JOB HAS BEEN IDENTIFIED, THE SLOT BASIC TIME IS ASSIGNED TO THAT JOB.

– BECAUSE OF THE HIGH SETUP COST OF THIS SYSTEM, THIS TECHNIQUE IS MOST SUITABLE FOR SITUATIONS WHERE THERE IS A LOT OF LONG CYCLE, NON-REPETITIVE WORK e.g. MAINTENANCE WORK WHERE THE WORK IS SIMILAR BUT NO TWO JOBS MAY BE IDENTICAL

METHOD STUDY

• DIAGRAMS– STRING DIAGRAM

• STRING STRUNG TO FOLLOW PATH TAKEN BY MATERIAL• DEALS TO SOLVE COMPLEX MOVEMENT & PLANT LAYOUT

– CYCLE GRAPH• INTRODUCED BY GILBERTH• PHOTOGRAPHIC METHOD • VERY ACCURATE• USED FOR RECORDING VERY FAST MOVEMENT NOT

POSSIBLE FOR SEEING BY EYE• LITTLE LIGHT ATTACHED TO THE FINGER OR HAND OF

OPERATOR TRACES THE PATH OF THE LIMB MOVEMENT ON A PHOTOGRAPHIC PLATE AS A CONTINUOUS LINE

• DOES NOT INDICATE DIRECTION OR SPEED

• 3. EXAMINE CRITICALLY• EACH ACTIVITY CRITICALLY EXAMINED AFTER

RECORDING ALL RELEVANT INFORMATION ABOUT THE SAME– ALL ACTIVITIES FALL INTO TWO CATEGORIES

• VALUE ADDING ACTIVITIES: WHERE SOME WORK IS BEING DONE ON THE MATERIAL

• NON VALUE ADDING ACTIVITY: WHERE NO WORK IS BEING DONE ON THE MATERIAL

– EFFICIENCY CAN BE IMPROVED BY INCREASING THE PROPORTION OF THE VALUE ADDING ACITIVITIES BECAUSE THESE ARE THE PRODUCTIVE ACTIVITIES

METHOD STUDY

• EXAMINE CRITICALLY contd…– TWO SETS OF DETAILED QUESTIONS ARE ASKED

• PRIMARY– TO INDICATE FACTS AND THE REASONS UNDERLYING

• SECONDARY– TO INDICATE ALTERNATIVES AND MEANS OF

IMPROVEMENTS– QUESTIONING PATTERN

• PURPOSE FOR WHICH, PLACE AT WHICH, SEQUENCE AT WHICH, PERSON BY WHOM, AND MEANS BY WHICH, THE ACTIVITIES ARE UNDERTAKEN

• WITH A VIEW TO ELIMINATE , COMBINE, REARRANGE OR SIMPLIFY THOSE ACTIVITIES

– TYPICALLY• PURPOSE: (P) WHAT IS DONE, (P) WHY IS IT DONE, (S) WHAT

ELSE CAN BE DONE, (S) WHAT SHOULD BE DONE– BRAIN STORMING AND CREATIVE THINKING SESSION

METHOD STUDY

• PROCEDURE ….contd• 4. DEVELOP AND EVALUATE THE BEST

METHOD– RECORD METHOD PROPOSED– CONSULT MANAGEMENT & WORKERS FOR THEIR

SUGGESTIONS– WORKOUT COST OF INSTALLING NEW METHOD– PREPARE NEW FLOW PROCESS CHART– PUT UP REPORT FOR MANAGEMENT APPROVAL

METHOD STUDY

TIME STUDY - STEPS

• IDENTIFY JOB AND OPERATION TO BE TIMED• USE IMPROVED PROCEDURE• SELECT WORKER AND BRIEF HIM AND HIS SUPERIOR

ABOUT STUDY• COLLECT EQUIPMENTS, ARRANGE MACHINE, JIGS ,

FIXTURES ETC• BREAK JOB INTO OPERATIONS / ELEMENTS• DETERMINE NUMBER OF OBSERVATIONS TO BE TIMED

WORK SAMPLING

• TECHNIQUE IN WHICH – LARGE NUMBER OF OBSERVATIONS ARE MADE OVER A

PERIOD OF TIME OF ONE OR A GROUP OF MACHINES, PROCESSES OR WORKERS

– RECORD WHAT IS HAPPENING AT THAT INSTANT• PERCENTAGE OF OBSERVATIONS RECORDED FOR A

PARTICULAR ACTIVITY OR DELAY IS A MEASURE OF THE PERCENTAGE OF TIME DURING WHICH ACTIVITY OR DELAY OCCURS

• NORMAL FREQUENCY DISTRIBUTION AND CONFIDENCE LEVEL ARE ASSOCIATED WITH WORK SAMPLING

• A CONFIDENCE LEVEL OF 95.45% SIGNIFIES THAT THE WORK STUDY ENGINEER IS SURE THAT 95.45% OF THE TIMES, THE RANDOM OBSERVATIONS WILL REPRESENT THE TRUE FACTS

BELL SHAPED CURVE

-1 +1-2 +2

-3 +3

68.27

95.45

99.73

Standard Deviation Confidence Level %1.00 68.271.96 95.002.00 95.453.00 99.73

WORK SAMPLING….contd

• NUMBER OF OBSERVATIONS TO BE MADE

N = 4*p*(100 – p ) / L2 , WHERE

N = NUMBER OF OBSERVATIONS,

p = PERCENTAGE OF OCCURANCE,

L = LIMIT OF ACCURACY

• COMPONENTS OF A BASIC PMTS ARE– REACH : MOVE HAND TO DESTINATION– GRASP : SECURE CONTROL OF OBJECT WITH

FINGERS– MOVE : MOVE OBJECTS– POSITION: LINE UP & ENGAGE OBJECT– RELEASE : LET GO OF THE OBJECT– BODY MOTIONS : LEG / TRUNK MOVEMENT

• PMTS TABLES ARE AVAILABLE FOR STANDARD TIMES FOR EACH TYPE OF MOTION UNDER GIVEN CIRCUMSTANCES

PRE-DETERMINED MOTION TIME SYSTEM (PMTS)….contd

• STEPS– IDENTIFY BASIC MOTIONS CONSTITUTING OPERATION– GET STANDARD TIME FROM PMTS TABLES FOR

IDENTIFIED MOTIONS– ADD AND GET BASIC TIME– ADD ALLOWANCES TO GET STANDARD TIME FOR THE

OPERATION

• RATING NEED NOT BE DONE AS TABLES CONTAIN ALREADY RATED TIMES

PRE-DETERMINED MOTION TIME SYSTEM (PMTS)….contd

• APPLICATION– DIRECT OBSERVATION OF THE MOTIONS USED BY THE WORKER

– MENTAL VISUALISATION OF MOTIONS NEEDED FOR THE NEW METHOD

– ANALYSIS OF A FILM / VIDEO TAKEN OF WORKER AT WORK PLACE

• ADVANTAGES– USE OF PMT STANDARD AVOIDS RATING WHICH LEADS TO

CONSISTENCY IN SETTING TIME STANDARDS

– ENABLES DETERMINING STANDARD TIME FOR A PROCESS DURING DESIGN STAGE ITSELF FOR SUITABLE MODIFICATION

– COST ESTIMATES ARE ALSO POSSIBLE

– PMTS IS LESS TIME CONSUMING THAN OTHER METHODS

– USEFUL FOR SHORT CYCLES

PRE-DETERMINED MOTION TIME SYSTEM (PMTS)….contd

• LIMITATIONS– LOT OF PRACTICE REQUIRED TO APPLY CORRECTLY– DEALS ONLY WITH NORMAL MANUAL MOTIONS OF AN

OPERATION – DIFFICULT FOR ABNORMAL MOTIONS– ALL CATEGORIES OF MOTIONS NOT CONSIDERED

WHILE COLLECTING PMTS DATA

PRE-DETERMINED MOTION TIME SYSTEM (PMTS)….contd

ANALYTICAL ESTIMATES

• STEPS INVOLVED ARE:– BREAK THE JOB INTO ELEMENTS– USE STANDARD DATA TO GET TIME VALUES OF

ELEMENTS FOR WHICH SUCH INFORMATION IS AVAILABLE

– MEASURE THE TIME VALUES OF ELEMENTS WHICH ARE WORTH THE EFFORT

• TECHNIQUE IS A COMBINATION OF INFORMATION FROM STANDARD DATA, TIME STUDY AND ESTIMATION

• OVERALL TIME FOR THE JOB WILL BE WITHIN ACCEPTABLE LIMITS

COMPARATIVE ESTIMATION

• RELIES ON IDENTIFICATION & MEASUREMENT OF BENCHMARK JOBS OF KNOWN WORK CONTENT AGAINST WHICH ALL OTHER JOBS TO BE MEASURED ARE COMPARED

• BECAUSE OF THE HIGH SETUP COST OF THIS SYSTEM, THIS TECHNIQUE IS MOST SUITABLE FOR SITUATIONS WHERE THERE IS A LOT OF LONG CYCLE, NON-REPETITIVE WORK e.g. MAINTENANCE WORK WHERE THE WORK IS SIMILAR BUT NO TWO JOBS MAY BE IDENTICAL