1 ISE Ch. 26: 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.

2 ISE Therbligs The smallest unit of activity in a task. “Gilbreth” backward (sort of) from:

3 ISE Methods-Time Measurements (MTM) Developed in 1946 Simplified versions are available. A training course is required for using the system correctly.

4 ISE MTM-1 10 categories of movements Times in TMUs (1 TMU = h) Times are for an experienced worker working at a normal pace. No allowances are included in the times.

5 ISE Reach (table 26.1, pg. 503) 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. Reach to a very small object or where accurate grasp is required. Reach to an indefinite location.

6 ISE Move (table 26.2, pg. 504) Move object to the other hand or against stop. Move object to an approximate or indefinite location. Move object to an exact location.

7 ISE Turn (table 26.4, pg. 506) 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 (table 26.5, pg. 506) Application of force without resultant movement.

8 ISE Grasp (table 29.6, pg. 567) Pickup grasp Regrasp Transfer grasp Jumbled grasp Contact, sliding, or hook grasp

9 ISE Position (table 26.7, pg. 508) 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

10 ISE Disengage (table 26.8, pg. 509) Breaking contact between one object and another Times vary with:  Class of fit  Ease of handling  Care in handling

11 ISE Release (table 26.9, pg. 509) Relinquishing control of an object by the hand or fingers Two types:  Simple opening of the fingers  Contact release

12 ISE Other Motions Body, leg, and foot motions Eye motions Combined motions Limited motions

13 ISE MTM Form

14 ISE 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.

15 ISE MTM-2 Analysis

16 ISE 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.) and uses time from table. Includes 2 other motions.

17 ISE MTM-3 Analysis

18 ISE 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 (pp. 513 – 516)  General move sequence [A B G A B P A]  Controlled move sequence [A B G M X I A]  Tool use sequence [A B G A B P use* A B P A]  Manual crane sequence [A B G M X I A, specific to crane use.]

19 ISE General Move Sequence Model

20 ISE Your turn … Perform a MOST analysis of the peg board task. Perform a MOST analysis of writing “MOST” on your notes with a pencil (assume the pencil is picked up from the desk at the beginning and returned to the desk at the end of the task.)

21 ISE 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).

22 ISE 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. For the most part, consistency and cost are more important than accuracy.  a consistent deviation from reality can be adjusted for Purpose of a PTS study  use methods analysis to determine an efficient work method  determine the amount of time necessary to do the job