Chapter 26

Predetermined Time Systems

Learning Outcomes

After careful studying this chapter You should be able to:

Define PTS

Discuss the purpose of PTS

Distinguish between the different types of MTM

Explain what is MOAPTS and what is MOST?

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.

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.

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 (floor).

No allowances are included in the times.

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.

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.

Grasp

Pickup grasp

Re-grasp

Transfer grasp

Jumbled (disorderly) 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

Disengage

Breaking contact between one object and another

Times vary with:

– Class of fit

– Ease of handling

– Care in handling

Release

Relinquishing control of an object by the hand or fingers

Two types:

– Simple opening of the fingers

– Contact release

Other Motions

Body, leg, and foot motions

Eye motions

Combined motions

Limited motions

MTM Form

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

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

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.

(MOST: Maynard Operational Sequence Technique)

General Move Sequence Model

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).

“MODular Arrangement of Predetermined Time Standards”

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.