Department of Industrial Engieering. Chapter : Predetermined Time Systems (PTS)

Transcription

1 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. 1

2 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 = HOUR 1 HOUR = TMU 1 TMU = MINUTES 1 MINUTE = 1667 TMU 1 TMU = SECONDS 1 SECOND = 27.8 TMU 2

3 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 = h) Times are for an experienced worker working at a normal pave. No allowances are included in the times. 3

4 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. 4

5 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. 5

6 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 6

7 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 7

8 Other Motions Body, leg, and foot motions Eye motions Combined motions Limited motions MTM Form 8

9 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 9

10 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 10

11 MOST Work Measurement System (Maynard Operation Sequence Technique) 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 General Move Sequence Model 11

12 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. 12

13 End of Chapter 13