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Procedure for the determination of time

required to perform a task involving either human

or machine under certain standard conditions of

measurement

• Direct time study

• Predetermined time system

• Standard time data

• Work sampling

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Systematic procedure that divides an

operation into motions or work elements, with a

set of time data assigned to each elements

• Allowance excluded

• Various available systems, for examples

• Work - Factor System

• Method - Time Measurement (MTM)

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• Developed from 4-year implementation of Micromotion study

• Employed in 1938

• Four techniques:

• Detailed• Ready • Brief• Mento-Factor

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• Body Members

Finger, Hand, Arm, Body, Leg , Foot, etc.

• Distance by Inch

• Weight & Resistance

• Manual Control

Basic, Definite stop, Directional control,

Care, Change of direction

Time Unit: 1/10,000 min

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• Body Members

• Distance by Inch

• Weight & Resistance

• Manual Control

T, FT, L, HT

F, H, A, FS

0 = Basic

1, D = Definite stop

2, S = Directional control

3, P = Care

4, U = Change of direction

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A10

Description of job: …..

Time Required: …...

A30WS

Description of job: …..

Time Required: …..

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• More Focus on Basic elements

• First developed for Drill Press Work

• Time Unit: 1/ 100,000 hr

(TMU, 0.0006 min)

• A family of MTM

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• Transport (Reach & Move)

• Grasp

• Pre-Position

• Assemble

• Use (Manual, Process or Machine)

• Disassemble

• Mental Process

• Release

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Reach• Class of Reach: A - E

• Distance measured in Inch

• Motion of hand

• Example: R8C, Time Unit= 11.5

• Equivalent to …… Min.

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Move• Class of Move: ……..

• Load measured in …….

• Motion of hand ??

• Example: mM10C, Time Unit= …...

• Equivalent to …… Min.

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• Trial time study, Based on work instruction & work station layout

• Verify time data, Compared to Direct time study

• Applicable to most of jobs

• No Rating Factor

• Facilitate Motion-Minded training

• Tools & equipment Design / Setup

• Estimate processing time required for cost

estimation

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• Selection of Various Systems

• Well trained analyst

????

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Applications

1) Determine machine utilization / downtime

2) Determine allowances

3) Establish time standards

Concept: To find out the proportions of total time

devoted to various activities that constitute a

job, by taking a large number of observations

at random times.

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Basic idea

• Random sampling over a long period of working hour

• Binomial distribution: p,q ratio out of n observations,

which approaches Normal distribution when n is large

npq

Distribution of a proportion: at 95%CI and +/- 5% relative accuracy, Z = 1.96

Mean, proportion of working time = p

Standard Deviation =

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0) Obtain cooperation from all concerns

1) Trial observations or a past record

2) Determine the number of obs. needed: Alignment chart

3) Design data collection procedure

a. Observer: number of person, position

b. Period of the study

c. Time table for daily random observation

d. Observation sheet

4) Assure 95% CI and +/- 5% relative accuracy

5) Calculate utilization ratio or standard time

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Table of Random Numbers

Daily working hours

Frequency of daily obs.

Routes of observation

Observation sheet

Observe At First sight

Data Summary and control

Recheck CI and accuracy level

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Control Chart (P chart) is to make sure every reading is in normal condition

mean

UCL = p + 3sigma

LCL = p - 3sigma

day

p, daily

mean = expected value of relevant proportion, p

sigma = standard deviation of p

3 sigma = 99.7% of population should fall within the range

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P chart: To detect unusual situation during the study

Within chart values

Out of chart values

Reasons of the unusual daily p

a) accident

b) lack of proper production flow

c) a change in expected value of p reconstruct the p chart, using the new information

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• 95% CI & +/- 5% relative accuracy

• Alignment chart or

Table for determining the number of obs.

given degree of accuracy, value of p at 95% CI

• Table for determining the degree of accuracy given number of obs., value of p at 95% CI

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total output during total time

Rep. Time = (total time spent) (proportion)

Normal Time = Rep. Time (Performance Index)

Std. Time = Normal Time + Allowances

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Advantages: compared with Direct time Study

• No continuous observation

• Normally less cost

• Study crew operation by one analyst

• Study long cycle time operation

• Easy to observe

• Don’t need specialist

• Operator would not feel under too much attention

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Disadvantages

• No details about operation

• Not suitable for short cycle task

• ??