department of industrial engieering chapter...

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Islamic University of Gaza - Palestine

Department of Industrial Engieering

Chapter : Predetermined Time Systems (PTS)

Assistant Prof. Abed Schokry


Predetermined Time Systems

• To increase productivity for a particular task:

– Frank and Lillian Gilbreth broke work into therbligs (elements).

– Then assign time values to the elements.

– Times for elements are added to obtain a total time.

• Independence and additivity are assumed.

• PTS are based on the concept that there are basic, universal units of work with standard amounts of time.

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Purposes of PTS Studies

• Make a methods analysis to determine an efficient work method.

• Determine the amount of time necessary to do the job.


Methods-Time Measurements

• Developed in 1946

• Simplified versions are available.

• A training course is required for using the system correctly.

• TIME UNITS:

1 TMU = 0.00001 HOUR 1 HOUR = 100000 TMU1 TMU = 0.0006 MINUTES 1 MINUTE = 1667 TMU1 TMU = 0.036 SECONDS 1 SECOND = 27.8 TMU

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Why MTM?

• In order to effectively utilize the man power,

• To balance the line and to establish the no. of workstations,

• Then to determine the moving speed, which depends upon the time taken at each station.


MTM-1

• 10 categories of movements

• Times in TMUs (1 TMU = .000 010 h)

• Times are for an experienced worker working at a normal pave.

• No allowances are included in the times.


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Types of Reach

• To an object in a fixed location or in the other hand.

• To a single object whose general location is known.

• To an object jumbled with others in a group.

• To a very small object or where accurate grasp is required.

• To an indefinite location.


Types of Move

• Move object to the other hand or against stop.

• Move object to an approximate or indefinite location.

• Move object to an exact location.


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Turn

• A movement that rotates the hand, wrist, and forearm about the long axis of the forearm.

• Time depends on degrees of turn, weight of the object, and resistance against turn.


Apply Pressure

• Application of force without resultant movement.


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Grasp

• Pickup grasp

• Regrasp

• Transfer grasp

• Jumbled grasp

• Contact, sliding, or hook grasp


Position

• Aligning, orienting, or engaging one object with another

• Position times vary with:

– Amount of pressure needed to fit

– Symmetry of the object

– Ease of handling


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Disengage (free)

• Breaking contact between one object and another

• Times vary with:

– Class of fit

– Ease of handling

– Care in handling


Release

• Relinquishing (letting go) control of an object by the hand or fingers

• Two types:

– Simple opening of the fingers

– Contact release


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Other Motions

• Body, leg, and foot motions

• Eye motions

• Combined motions

• Limited motions


MTM Form


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MTM-2

• Takes about 40% of the time of MTM-1 to analyze a task.

• Has only 37 times in all.

• Key categories are GET and PUT.

• Provides decision trees to determine case.

• User estimates distance and uses time from table.

• Includes seven other motions.


MTM-2 Analysis


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MTM-3

• Takes about 15% of the time of MTM-1 to analyze a task.

• Has only 10 times.

• Key categories are HANDLE and TRANSPORT.

• Provides decision trees to determine case.

• User estimates distance (< 6 in. or > 6 in.) and uses time from table.

• Includes two other motions.


MTM-3 Analysis


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MOST Work Measurement System

• Based on observation that the majority of activities are associated with a limited number of motion sequences.

• Significantly reduces time required to perform an analysis.

• Four sequence models

The four sequences are:

• Basic MOST, Mini MOST, Maxi MOST, Admin MOST

(Maynard Operation Sequence Technique)


General Move Sequence Model


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MODlar Arrangement Of Predetermined Time Standards

MODAPTS

• Based on the concept that the body member used is the key variable.

• All body movements are multiples of a MOD (1 MOD = .129 s).


Comments about PTS

• In theory, PTS can accurately predict task times.

• Evidence shows reality and theory don’t agree.

• Analyst judgment is required (could be a problem).

• Most managements are not concerned with a great deal of accuracy.

• Managements are concerned with cost of analysis.


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End of Chapter


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