1. Predetermined Time Systems
Chapter 26
Predetermined
Time Systems

2. Methods To Set Time Standards
Estimation
Estimated times
Historical records
Historical times
Methods to set time standards
Work measure-ment techniques
Direct time studies
Engineered standards
Pre-determined time systems
Standard data systems
Work sampling
Proportions of work activities

3. Predetermined Time Systems
Frank and Lillian Gilbreth broke work into therbligs (elements).
The next step is to 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.

4. Methods-Time Measurements
Developed in 1946
Simplified versions are available.
A training course is required for using the system correctly.

5. MTM-1 10 categories of movements
Times in TMUs (Time Measurement Units)
1 TMU = h
= min
= s
Times are for an experienced worker working at a normal pace.
No allowances are included in the times.
Takes ~ 2,000 cycles to make MTM standard time.

6. Reach 5 cases: Parameterized by distance (inches) knuckle-to-knuckle
Reach to an object in a fixed location or in the other hand.
Reach to a single object whose general location is known.
Reach to an object jumbled with others in a group (requires search & select).
Reach to a very small object or where accurate grasp is required (visual control).
Reach to an indefinite location (minimum mental control).
Parameterized by distance (inches)
knuckle-to-knuckle
Must consider
shoulder, body movement (body assist)
acceleration, deceleration

7. Move Hand usually holding something. 3 cases: Parameterized by
Move object to the other hand or against stop (little control).
Move object to an approximate or indefinite location (some control).
Move object to an exact location (control).
Parameterized by
distance
object weight
Variation: Crank
parameterized by diameter

8. 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.

9. Apply Pressure
Application of force without resultant movement.

10. Grasp Pickup grasp Regrasp Transfer grasp Jumbled grasp
Contact, sliding, or hook grasp

11. 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

12. Disengage Breaking contact between one object and another
Times vary with:
Class of fit
Ease of handling
Care in handling

13. Release Relinquishing control of an object by the hand or fingers
Two types:
Simple opening of the fingers
Contact release

14. Other Motions Body, leg, and foot motions Eye motions Combined motions
e.g., Regrasp during Move
time is greater of two times
Limited motions
accuracy required for one motion limits accuracy of simultaneous motion
requires continuation of limited motion after limiting motion is completed

15. MTM Form

16. 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 7 other motions.

17. MTM-2 Analysis

18. MTM-2 Exercise

19. 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 2 other motions.

20. MTM-3 Analysis

21. 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.
4 sequence models.

22. General Move Sequence Model

23. 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).

24. Comments about PTS In theory, PTS can accurately predict task times.
Evidence shows reality and theory don’t agree.
One problem is that analyst judgment is required.
Most managements are not concerned with a great deal of accuracy.
Managements are concerned with cost of analysis.