time & motion study

4/11/2013

© Copyright 2013 Anupam Kumar 1

Time & Motion Study

Presented By:

Anupam Kumar

Reader

SMS Varanasi.

Email: [email protected]

1© Copyright 2013 Anupam Kumar

Time & Motion Study

• Frederick W. Taylor and his followers developed and

refined the Time Study

• A method created to determine the ‘correct time’ it

takes to complete a certain task

• Frank B. Gilbreth and his wife Lillian developed and refined the Motion Study

• A method to establish ‘the one best way to perform a task’

• Historically the two studies are discussed individually, today they generally are discussed as one


Time Study

• It is a work measurement technique

– for recording the times and rates of working

– for the elements of a specified jobs,

– carried out under specific conditions

– for analyzing the data

– so as to obtain the time necessary

– for carrying out the job

– at an defined level of performance.


Motion Study

• It is the science of eliminating wastefulness resulting from using– unnecessary,

– ill-directed and

– inefficient motion.

• The aim of the study is to find and perpetuate the scheme of least waste methods of labour.– Workers do not enjoy making unnecessary or wasted

motions, as they result in needless fatigue.

– Motion study thus helps in reducing fatigue & waste motions.


Use of Time & Motion Study

• Historically:

– T&M Studies were used in the manufacturing industry to

evolve pay scales with the thought that money was the

only motivation for work.

• Today:

– T&M Studies can be effective for performance evaluations

– T&M Studies can be used for planning purposes in order to predict the level of output that may be achieved

– T&M Studies can be used to uncover problems and create solutions

– T&M Studies can be used for time cost analysis


Objectives of Time & Motion Study

• Estimation of realistic manpower

requirement.

• Comparison of alternative methods of

working.

• Establishment of incentive schemes

• Improved control over operations.

• Proper work distribution.

• Future manpower and cost forecasting.


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Steps Involved in T&M Study

• Selection

• Obtain all necessary information

• Divide the job into job-elements

• Time each element

• Number of cycles to be timed

• Rate the operator

• The rating of the operator to be objective

• Make provisions for allowances.


Job Element

• Should be as short as possible and should be conveniently timed.

• Should be unified and should have logical sequence of basic motions.

• Constant and variable elements should be separated for generation of data for subsequent studies.

• Regular and Irregular elements should be separated so as to provide for time allowances.

• Elements involving heavy and fatigue work should be separated to allow for proper allowances.


Determination of Times

• Standard Time

– It is the time required

– by an operator of average skill

– who expends an average amount of effort and

– is working under average conditions.

• Use of Standard Time

– To establish minimum performance requirements

– Control of labour cost

– Planning wage incentive schemes

– Product line balancing.



• Performance Rating

– It is the pace of the actual work being done as a

percentage of the standard pace of doing the same work.

• Level of Performance

– It is the rate of output achieved by a qualified worker as an

average for the day.

• Normal Time

– It is the productive time needed to perform a task, utilizing

appropriate work methods, work area layout and

performing at a pace the firm defines as normal.



• Actual Time

– It is the time actually taken in completing the desired task.

– If the operator works at 100% efficiency then the actual time would be equal to the normal time.

• Use of Actual Time

– In method study

– In plant layout planning

– In setting realistic starting and finishing times for operator.



• Allowance

– Standard times for elements or jobs are necessary to

provide for allowances for compensating fatigue, personal

needs, contingencies, etc.

– These are generally given as a percentage of the standards

time or normal time.

– If allowance is given as a percentage of normal time

• Standard Time = Normal Time (1+Allowance)

– If allowance is given as a percentage of standard time

• Normal Time = Standard Time (1 – Allowance)


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Allowances or Time Allowances

• Relaxation Allowance

– For fatigue and personal needs

• Contingency Allowance

– For duties of periodic nature

• Tools and Machinery Allowance

– For adjusting machines, sharpening tools, etc.

• Reject Allowance

– Time used up in producing items which turn out to be defective

• Interference Allowance

– Stoppage of 2 or machines

• Excessive Work Allowance

– Due to unforeseen temporary changes


Illustration 1

• How many working minutes do you expect

would take a worker to produce a part for

which

– the time standard is 10 minutes,

– if the allowance for this work is 25% of the normal

time and

– the worker is rated at 80%?

Click for Solutions


Solution to Illustration No. 1

Standard time = 10 Min

Allowance = 25% of N.T.

ST = NT (1+All.)

⇒NT = ST / (1 + All.)

⇒NT = 10/(1+25%)

⇒NT = 8 Min

Performance Rating = (Normal

time) / (Observed time)

⇒OT = NT / (Per. Rating)

⇒OT = 8/(80%)

⇒OT = 10 Min.

Standard time = 10 Min

Performance Rating = 80%

Actual time = ST/Per. Ratg

⇒AT = 10/(80%)

⇒AT = 12.5 Min.

Actual time = Observed time

*(1+All.)

⇒OT = AT / (1+ All.)

⇒OT = 12.5 / (1+25%)

⇒OT = 12.5 X 4/5

⇒OT = 10 Min.15© Copyright 2013 Anupam Kumar

Illustration 2

• Calculate the standard production per shift of

8 hours duration, with the following data.

– Observed time per unit = 5 minutes

– Rating factor = 120%

– Total Allowance = 33.33% of normal time.

Click for Solutions


Solution to Illustration No. 2

OT = 5 Min

Per. Ratg. = 120%

All. = 33.33% of NT

NT = OT * Per. Ratg.

⇒NT = 5 X 120/100

⇒NT = 6 Min.

ST = NT (1+ All.)

⇒ST = 6 (1+33.33%)

⇒ST = 6X4/3

⇒ST = 8 Min.

8 Min. is needed for 1 Unit

⇒ 1 Min. is needed for 1/8 unit

⇒ 8 Hrs. is needed for 8 X 60/8

Units

⇒ 8 Hrs. is needed for 60 units.

• The standard production

per shift is 60 Units.


Methods of Time Estimation

• Study of Past Production Records

– It is an invaluable source of information regarding

the time taken to perform a particular task.

– It is however assumed that the nature of activities

performed in the process does not change over

the period of time.

• Estimation Method

– It involves the analysis based on the experience &

judgment of the observer.


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Work Measurement Techniques

• Direct Time Study Methods

– Analytical Estimation

– Work Sampling

• It is based on statistical estimation of work during various time samples.

• Indirect Time Study Methods

– Synthetic Timing Data

• It is based on the previous data available with the establishment which helps in synthesizing the overall data

– Predetermined Motion Time Studies (PMTS)

• It is based on the standard data available based on the various micro motion studies.


Illustration 3

• Calculate the standard time per article produced

from the following data obtained by a work sampling

study.

– Total No. of observations = 2500

– No. of working observations = 2100

– No. of units produced in 100 hours duration = 6000

– Proportion of manual labour = 2/3

– Proportion of machine time = 1/3

– Observed rating factor = 115%

– Total allowance = 12% of normal time.Hint


Hint for Illustration 3

• Actual Working time in 100 hours = 100*2100/2500 = 84

• Time taken per article = 84*60/6000 = 0.84 Min.

• Observed Manual time = (2/3) * 0.84 = 0.56 Min.

• Observed Machine time = (1/3) * 0.84 = 0.28 Min.

• Normal Labour time = Observed Manual time * Rating Factor

= 0.56 * 1.15

• Standard Labour Time = (0.56*1.15) * (1+ 12/100)

= 0.56*1.15*1.12

• Standard time per unit = Standard Labour Time + Observed Machine Time


Illustration 4

• After application of work simplification techniques and a

direct time study of elements the following time elements in

minutes were obtained as in table below.

Job

Element

Cycle

1 2 3 4 5

1 0.16 0.12 0.13 0.15 0.24

2 0.60 0.60 0.60 0.60 0.60

3 0.33 0.50 0.35 0.37 0.35

4 0.50 0.50 0.50 0.50 0.50

5 0.24 0.24 0.25 0.27 0.25


Illustration 4 (Contd.)

• The following information was also determined about the job.

– Job Element 2 & 4 are machine controlled and cannot be speeded up

by the operator

– There were 2 irregular occurrences while timing.

– The operator was rated at 110% when working.

– Personal allowance – 30 min/day; Unavoidable delays – 20 min/day &

Fatigue 10% of the operator’s actual physical time.

– Shift is 8 hour long.

• Calculate standard time per unit & shift output standard.

Hint


Hint for Illustration 4

• Identify the Irregular occurrences.

• Calculate the average time for each job element.

• Calculate Normal Time and then Standard Time by using the

data given for allowances.

Job

Element

Cycle Ave.

Time1 2 3 4 5

1 0.16 0.12 0.13 0.15 0.24 0.14

2 0.60 0.60 0.60 0.60 0.60 0.60

3 0.33 0.50 0.35 0.37 0.35 0.35

4 0.50 0.50 0.50 0.50 0.50 0.50

5 0.24 0.24 0.25 0.27 0.25 0.25


Solution

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Solution for Illustration No. 4

OTJE1 = 0.14

⇒NTJE1 = OTJE1 X Per. Rat.

⇒NTJE1 = 1.4 X 110/100

⇒NTJE1 = 1.54

Similarly,

NTJE3 = 0.385

NTJE5 = 0.275

NTmanual = 0.814

Tmanual = 0.814 * 1.10 = 0.8954

NTtotal = Tmanual + Tmachine

NTtotal =0.8954+0.50+0.60 =

1.9954

ST = NTtotal / (1 – AllowanceST)

Allowance = (30 + 20) / (8 * 60)

Allowance = 0.104167

ST = 1.9954 / (1- 0.1042)

ST = 1.9954 / 0.8958 = 2.227

min

Standard Time = 2.23 minute

Shift Output = 8 * 60 / 2.23

Shift Output = 215.25 Units.


Illustration No. 5

• An operator manufactures 50 jobs in 6 hours

and 30 minutes. If this time includes the time

for setting the machine. Calculate the

operator’s efficiency. Standard time allowed

for the job is as follows.


Sr. No. Job Element Details

1. Setting Time 35 minutes

2. Production time per piece 8 minutes

Solution


• 50 Jobs in 6 hours and 30 minutes

⇒50 Job in (6*60 +30) minutes = 390 minutes

• Standard Time = Setting time+Production time

⇒S.T. = 35 + 8*50 = 35 + 400 = 435 minutes

• Per. Rating = Standard Time / Actual time

⇒Per. Rat. = (435 / 390)*100 = 111.5%


Illustration 5

• Time data taken for a bulk filling activity in Bangalore were recorded on a

continuous basis as shown below.

• The firm’s labour contract requires a 15% allowance based on total time

for all workers on the bulk filling line

• Compute the standard time for this activity.

Cycle Time (in Sec.) Rating

Factor

1 2 3 4 5

Grasp Bag 4 37 74 105 338 120

Locate for fill 16 51 84 117 352 120

Machine Fill 26 61 94 127 362

Set on Conveyor 34 68 102 334 369 110


Hint

Hint for Illustration No. 6


Cycle Time (in Sec.) Rating

Factor

1 2 3 4 5

Grasp Bag 4 37 74 105 338 120

Locate for fill 16 51 84 117 352 120

Machine Fill 26 61 94 127 362

Set on Conveyor 34 68 102 334 369 110

Grasp Bag 4 3 6 3 4 120

Locate for fill 12 14 10 12 14 120

Machine Fill 10 10 10 10 10

Set on Conveyor 8 7 8 207 7 110

Solution


• Allowance = 15% on total time = 15% of Standard Time

• Normal Time = (OT1 XPer.Rat.1 + OT2 XPer.Rat.2 +OT3 + OT4 XPer.Rat.4)

• Normal Time = 4*1.2 + 12.4*1.2+10+7.5*1.1 = 4.8 + 14.88 + 10 + 8.25

• Normal Time = 37.93 sec.

• Standard Time = NT / (1 – All.) = 37.93 / (1 – 0.15) = 37.93/0.85

• Standard Time = 44.62 sec.


Cycle Time (in Sec.) Average

1 2 3 4 5

Grasp Bag 4 3 6 3 4 4

Locate for fill 12 14 10 12 14 12.4

Machine Fill 10 10 10 10 10 10

Set on Conveyor 8 7 8 207 7 7.5

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Further Numericals

• Assuming that the total observed time for an operation of

assembling an electric switch is 1 minute. If the rating is 125%,

find normal time. If an allowance of 20% is allowed for the

operation for employee fatigue, determine the standard time.

• Find out the standard time using the following data:


Sr. No. Job Element Details

1. Average time for machine element 7 min.

2. Average time for manual element 5 min.

3. Performance Rating 120%

4. Allowance (as a percentage of S.T.) 15%

For further details,…

Contact:

Anupam Kumar

Reader,

SMS Varanasi.

Email: [email protected]


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