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.