05work Measurement

7/31/2019 05work Measurement

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WORK MEASUREMENTThe objective of any work measurement system is todetermine the time it should take an average, trainedperson to perform a task

if he or she were doing that over an 8-hour day

under usual working conditions and working at a normal pace.

This time is called standard time.

There are two basic approaches to defining standardtime.


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WHY WORK MEASUREMENTS

To determine efficiency of jobs

Determining equipment requirements.

Determining labor requirements.

Designing training methods.

Designing scheduling procedures.

Designing incentive systems.

Gauging work performance. Estimating cost.


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THE TWO APPROACHESThe bottom-up

starts with a basic measurement of time, adjusts for operator pace, and then allows for fatigue, personal needs, and

delaysThe top-down

used in many labor contracts. It normally defines standard time as thattime under which a qualified employeeworking under usual conditions can make an

incentive pay (specified) percent above basepay.


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SOME IMPORTANT DEFINITIONSNormal Time. The time required for an average, trained operator

to perform a task under usual working conditionsand working at a normal pace.

Normal Pace The pace of an average, trained, and

conscientious operator working over an 8-hourday.

Actual Time. The observed time required for an operator to

perform a task.

Allowances. The amount of time added to the normal time toprovide for personal needs, unavoidable delays,and fatigue.


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DEFINITIONS

Qualified worker: physical sufficiency, intelligence,train and skills for safely working, quality andamount.

Determined task (Task bringing standard) :Task is reported point of view production methods

Determined productivity level: Qualified workerperforms task with great motivation and nonoverloading during on a day or one shift.Finally task gives average output.

Standard performance is the rate of output which

qualified workers will achieve without over-exertionas an average over the working day provided theyare motivated to apply themselves to their work.


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METHODS OF DETERMINING

STANDARD TIMES. Direct time study.

Time study standard data.

Predetermined time systems.

Predetermined time systems standarddata.

Work sampling.


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DIRECT TIME STUDY

Direct time study is a work measurementtechnique in which

A physical measurement is made of the

actual time required to do a task byusing a watch or some other timingdevice.

This measured time is then modified byconsidering the operator's pace, andfinally, allowances are added.


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TIME STUDY BOARD


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TIME SHEET FRONT SIDE

Date Name Sketch

Operation

Operator Dept

Part No.

Special Equipment

Left Hand Right Hand Element No. Feeds Speeds Special Tools, e tc.

Notes


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TIME SHEET BACK SIDE


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PROCESS The front of the sheet is for recording the

task being studied, the existing procedure indetail, and any other pertinent information.

The back of the sheet is for recording the

actual time study.The task is broken down into easily discernibleelements,

The elements are recorded, and then the timing

is done.The watch reading is recorded in column R,

( the watch does not stop) and the time foreach element is entered in column T later.


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HOW IT WORKS

1. Establish the

standard jobmethod.

2. Break down the

job into elements

3. Study the job.

4. Rate the workersperformance


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HOW IT WORKS(contd.)

5. Compute the average time

6. Compute the normal time

Nt=(t)(RF) or

Normal Time=(elemental average time)

(rating factor)

7. Compute the standard time

ST=(Nt)(1+AF) or

Standard Time=(Normal cycletime)(1+Allowance factor)


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EXAMPLE Total actual time = 15 + 7 + 5 + 8 = 35

Performance rating = 115%

Normal time = (35)(1.15) = 40.25Allowances = 12%

Standard time = (40.25)(1.12) = 45.08


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Experiencedworker

Trainee

DISTRIBUTION OFWORK TIMES


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The reason for thejobadjustment factoris that the worker being

observed may be working at a rate different from the normal rate(working at a deliberately slow rate, natural abilities differ from the norm,

working at a rate to impress the observer). Thus the observedtime is

adjustedby this factor to yield a more accurate work pace.

performance rating = 1.0 indicates the worker is working at anormal rate

performance rating = .90 indicates the worker is working at 90%

of a normal rate

performance rating = 1.10 indicates that the worker is working

10% faster than a normal rate

Job Standard Time


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SOME PRACTICAL PROBLEMS ?

Is the job ready for time study ?

Care During the Time Study

Dividing an Operation into Elements Taking and Recording of Data

Performance Rating

Allowances Number of observations to make

Foreign elements


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IS THE JOB READY FOR A TIME

STUDY? Need correct method

Materials in specification

Correct machine speed

All other conditions of work in standardsettings

Lastly, would a motion study bringabout improvements?


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DURING THE TIME STUDY

The time analyst should ask (for each phase):

Can the speed or feed be increased w/o hurting

quality? Can changes in tooling decrease cycle time?

Can materials be moved closer to work area?

Is equipment operating correctly, and a qualityproduct being produced?

Is the operation being performed safely?


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REASONS FOR ELEMENT

BREAKDOWN Data is more readily reusable when each

element is described separately, esp. beginningand ending points.

Standard (estimated) time values may bedetermined.

Individual elements may be excessively short

(e.g., inspection), or too long. These can bepicked out more easily in element form.

This allows for separate performance ratings foreach.


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DIVIDING AN OPERATION INTO

ELEMENTS1. The elements should be as short in duration as

can be accurately timed. (Not in individualhand motions, which are too short to time.)

2. Handling time should be separated frommachine time.

3. Constant elements should be separated from

variable elements (i.e., those that are sizedependent).

4. Regular elements are recorded first, then allothers.


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TAKING AND RECORDING OF DATA

Continuous timing - records readings atthe end of each element as watch runs

Repetitive timing - after recording, watchis snapped back to zero at the end of eachelement

Multiple watches - connected by a lever;

one runs, another is stopped, another set togo

Electronic watch - may continue in splitmode


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NUMBER OF OBSERVATIONS

When making a time studyseveral decisions are made to

assure desired results:

# of observations to make

Desired level of accuracy

Desired level of confidence for

the estimated standard time

Desired accuracy level is

typically expressed as a % of

the mean observed times The formula for determining

the number of observations

needed ?

n: number of observations

z: provides desired statisticalconfidence (e.g.: 1.96 for 95%)

s: observed standard deviation

in time required to complete thetask element

a: desired accuracy orprecision

x-bar: the mean observed timeto complete the task

2

x

s

a

zn


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Pizza Place: To determine a standard time to prepare a large pepperoni and

cheese pizza. Analyst takes 10 observations of the 7 elements and calculates

the mean time and the standard deviation per element. He must then

calculate the # of observations needed so that the time estimate is to be

within 5% of the true mean 95% of the time.

The analyst must calculate the observations for each element to determine how

many additional observations must be taken. The maximum number of 25 (in this

case) for element #7 means that an additional 15 observations must be made and

then the observed times are revised.

nsobservatio250.24

0.03

0.05

1.96

x

s

a

zn

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7

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A B C D E

Example 11.3 Pat's Pizza Place

Standard Deviation Mean Observed Revised Observed

Work Element (minutes) Time (minutes) Time (minutes) # Observations

1. Get ball of dough 0.010 0.12 0.15 11

2. Flatten dough 0.030 0.25 0.25 233. Spin and toss dough 0.040 0.50 0.60 10

4. Place dough on counter 0.005 0.12 0.15 3

5. Pour sauce on formed dough 0.035 0.30 0.30 21

6. Place grated cheese on top 0.025 0.25 0.28 16

7. Place pepperoni on sauce 0.030 0.24 0.28 25


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OTHER TIME FACTORS USED INCALCULATING STANDARD TIME

The normal time (NT) is the mean observed time multiplied by the

performance rating factor (PRF)

The PRFis a subjective estimate of a workers pace relative to a normal

work pace

The frequency of occurrence (F) is how often the element must be done

each cycle.

NT=(OT)(PRF)(F)

The allowance factor (AF) is the amount of time allowed for personal,

fatigue, and unavoidable delays

Standard Time=normal time x allowance factor, where:

(NT)(AF)ST

117.6%1.1760.151

1

PFD1

1AF WorkedTme


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CALCULATING NORMAL TIME ANDSTANDARD TIME AT PATS PIZZA

The standard time for preparing a large, hand-tossed pepperoni pizza is 2.312minutes. This means that a worker can prepare 207 pizzas in an 8-hour shift(480 minutes divided by 2.312 minutes)

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A B C D E F

Example 11.4 Calculating Standard Time for a Hand-Tossed Cheese and Pepperoni Pizza

Revised Observed Performance Rating Frequency Normal Time Standard Time

Work Element Time (minutes) Factor (minutes) (minutes)

1. Get ball of dough 0.15 0.90 1 0.135 0.1592. Flatten dough 0.25 1.00 1 0.250 0.294

3. Spin and toss dough 0.60 0.85 1 0.510 0.600

4. Place dough on counter 0.15 1.10 1 0.165 0.194

5. Pour sauce on formed dough 0.30 1.20 1 0.360 0.423

6. Place grated cheese on top 0.28 1.00 1 0.280 0.329

7. Place pepperoni on sauce 0.28 0.95 1 0.266 0.313Total Time 1.966 2.312


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FOREIGN ELEMENTS

A foreign element is one that does not

explicitly belong in the sequence Examples:

Worker has to adjust glasses,

Must speak to supervisor,

Rest break, lunch break, Wrench breaks, must find new wrench.

Some foreign elements can be eliminated, but otherscannot or should not be.

Foreign elements can give the analyst an idea of howmuch extra time is reasonable to allow in anoperation.


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CHECK LIST1. Secure and record information about the operation

and operator being studied.2. Orient the supervisor and the workers.

3. Improve the work methods.

4. Break the task into elements and record.

5. Observe and record the time taken by the operator.6. Determine the number of cycles to be timed.

7. Rate the operators performance.

8. Check to make certain that a sufficient number of

cycles have been recorded.9. Determine the allowances.

10. Determine the time standard for the operation.

11. Check and debug the standards with audits.

12. Implement with recall review in one month.


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New Tools

With this PDA, youcan study elements,

time, performancerate, and statisticalconfidence intervalscan be created,edited, managed, and

downloaded to aspreadsheet


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OTHER TIME STUDY METHODS

Elemental time data for typical work elements from

previously completed time studies can be stored in a

data base for use on future similar studies.

Predetermined time data (e.g. MTM and MTS) is a

larger database of valid work element times used to set

standards for common job elements

Reach, grasp, move, engage, insert, turn, etc. Work Sampling is a technique for estimating the

proportion of time a worker spends on an activity


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Rating scales

BritishStandard

I.L.O.

AmericanStandard

StandardPerformance

Incentive

Normal

100 80

6075

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05work Measurement