Time and motion study

(1)

Operations

Management

Work Measurement

Supplement 10

(2)

Outline

♦

Labor Standards and Work

Measurement

♦

Historical Experience

♦

Time-Studies

♦

Predetermined Time Standards

(3)

Learning Objectives

When you complete this supplement,

you should be able to :

♦

Identify or Define

:

♦

Four ways of establishing labor standards

♦

Describe or Explain

:

♦

Requirements for good labor standards

♦

Time study

♦

Predetermined time standards

♦

Work sampling

(4)

♦

Costing labor content of products

♦

Planning staffing needs

♦

Estimating time and cost for bids

♦

Planning production (crew size and work

balance)

♦

Basing wage-incentive plans

♦

Determining employee efficiency

Uses of Labor

Standards

(5)

♦

Historical experience

♦

Time studies

♦

Predetermined time

standards (MTM)

♦

Work sampling

Sources of Labor

Standards

(6)

♦

Labor standards are based on

observing worker doing task

♦

_{Observe only a sample of work}

♦

_{Use average time & pace to set}

standard

♦

Disadvantages

♦

_{Requires a trained & experienced}

analyst

♦

_{Standard cannot be set}

_before

_{task is}

performed

Time Studies

(7)

The Eight Steps to

Conducting a Time Study

➊

Define the task to be studied (after a methods

analysis)

➋

Break down the task into precise elements

➌

Decide how many times each element of the

task must be measured

➍

Record the times and ratings of performance

for the task elements

➎

Compute the average observed cycle time

(8)

➏

_{Compute the normal time for each}

task element:

Normal time = (Average actual

cycle

time) x (Rating

factor)

➐

_{Sum the normal times for each}

element to develop a total normal

time for the task

➑

_{Compute the standard time:}

The Eight Steps to

Conducting a Time

Study - continued

Standard time =

Total normal time

1- Allowance factor

(9)

Allowances

♦

Personal time allowance

- 4% - 7% of

total time - use of restroom, water

fountain, etc.

♦

Delay allowance

- based upon actual

delays that occur

♦

Fatigue allowance

- to compensate for

physical or mental strain, noise level,

tediousness, heat and humidity,

assumption of an abnormal position,

etc.

(10)

Time Studies - Sample

Size

2 











=

x

h

zs

n

,

size

Sample

h = accuracy level desired as

percent of job element, expressed

as a decimal (5% = 0.05)

z = number of standard deviations

required for the desired level of

confidence

s = standard deviation of the initial

sample

x = mean of the initial sample

(

)

1 −

−

=

∑

2 n

x

s

:

Note

i

(11)

Considerations in

Determining Sample

Size

❶

_{How accurate do you want to}

be?

❷

_{What level of confidence do}

you want your measurements

to have?

❸

_{How much variation exists}

(12)

Common z values

Desired Confidence

Level (%)

Z Value

90.0

1.65

95.0

1.96

95.4

2.00

99.0

2.58

99.7

3.00

99.0

(13)

Allowance factor

Nonwork time

Total time

Average element time

Σ

Element times

Number of cycles

Normal timeAverage element time * Perf. Rating

Standard time

Total normal time

1 - Allowance factor

=

Time Study Equations

(14)

♦

Labor standards are set from times in

published tables (e.g., MTM Table)

♦

Procedure

♦

_{Divide manual work into basic elements}

♦

_{Look up basic element times in table; sum}

♦

Advantages

♦

_{Times established in laboratory setting}

♦

_{Useful for planning tasks}

♦

_{Widely accepted by unions}

Predetermined Time

Standards

(15)

Time TMU

Hand in

Motion

Distance

Moved (in)

A

B

C

A

B

3/4 or less 2.0

2.0

1.6

1

2.5

3.6

2.3

2

4.0

5.9

3.5

2.7 A Reach to object in fixed location.

B Reach to object in variable

locations.

1 TMU = .

0006

minutes

MTM Table for Reach

Motion

(16)

Sample MTM Table for

GET and PLACE

Motions

(17)

♦

Labor standard is set using output and

% of time worker spends on tasks

♦

Involves observing worker at random

times over a long period

♦

Advantages

♦

Less expensive than time studies

♦

Observer requires little training

♦

Disadvantages

♦

Ineffective with short cycles

Work Sampling

(18)

♦

Used for

♦

_{Ratio delay studies}

♦

_{Setting labor standards}

♦

_{Measuring worker performance}

Work Sampling

(19)

The Seven Step

Work Sampling

Procedure

➊

Take a preliminary sample to obtain an

estimate of the parameter value

➋

Compute the sample size required

➌

Prepare a schedule for observing the

worker at appropriate times

➍

Observe and record worker activities;

(20)

The Seven Step

Work Sampling Procedure -

continued

➎

_{Record the number of units}

produced during the applicable

portion of the study

➏

_{Compute the}

_{normal time}

_per

part

➐

_{Compute the}

_{standard time}

_per

part

(21)

Work Sampling -

Sample Size

(

)

2

2 ₁

₋

=

h

p

z

n

p = estimated value of

sample proportion (of time

worker is observed busy or

idle)

h = accuracy level desired in

percent, expressed as a

(22)

Normal Time =

(Total Time) (% of time working) (Rating)

Number of units Produced

Standard Time =

Normal Time

1 - Allowance

Work Sampling

Equations

(23)

Figure S10.3