PTS (Predetermined Time system) took a long time to become part of general work study practice. The main reason for this delay is probably the considerable number and variety of systems that have been produced, together with the fact that many of them would be obtained only by employing consultants. At present, over 200 such systems exist.
1) Any PTS system is rather complicated. It is not easy to learn and a work study man needs a good deal of practice before he can apply it correctly.
2) The task of learning enough about the various systems to be able to judge their claims and their relative merits is an almost impossible one. For example some systems do not go into sufficient detail in defining a certain motion.
3) PTS systems do not, as was claimed, eliminate the need for the stop watch, any more than they eliminate method study or work sampling.
4) Machine time, process time and waiting time are not measurable with PTS systems and occasional or incident elements are often more economically measured by using other techniques.
5) In fact it is difficult to obtain 100% coverage in a plant using only a PTS system and for certain operations such as batch production or non-repetitive jobs the use of such a system can be an expensive proposition.
6) It is invalid to add up times for individual small motions in the way required by PTS systems because the time taken to perform a particular motion is influenced by the motions preceding and following it.
The main of PTS systems may be divided in the following two classes:
1) Improving existing methods
2) Evaluating proposed methods in advance of actual production
3) Evaluating suggested designs of tool, jigs requirement
4) Aiding in the design of the product
5) Training members of the staff to become motion-minded.
6) Aiding in training operators.
1) Establishing time standards.
2) Complication of standard data and formulae for specific classes of work
3) Checking standards established by time study
4) Auditing time standards
5) Estimating labor costs
6) Balancing production lines.
Nine predetermined time systems area as follows:
1) Motion Time Analysis (MTA) – A B Segur
2) Body Member Movements – WG Holmes
3) Motion Time Data for Assy, work – Harold Engstrom & HC Geppinger
4) The Work Factor System – J H Quick , W J Shea & R E Koehler
5) Elemental Time standard – Western Electric for Basic Manual work.
6) Methods Time Measurement (MTM)_ — H B Maynard, G J Stegements J L Schwab
7) Basic Motion Times study (BMT) – Ralph Presgrave , G B Bailey, J A Lowden
8) Dimensional Motion Tiems (DMT) – HC Geepinge
9) Predetermined Human Work Tomes – Irwin P Lazarus.
The First Predetermined Time system
A B Segur developed the first PTS system, which he called Methods Time analysis (MTA). He worked with Gilbreth during World War I using micro motion analysis of films. By 1924 Segur had perfected his system and made it available on a consulting basis. His data was never published. His system was very detailed and required a high degree of skill and training.
The Work Factor System:
It is a widely and generally used PTM system. The first actual shop application was made in 1938 and time values published in 1945. The system includes,
1) Detailed work factor
2) Ready work factor
3) Abbreviated (using Form A)
4) Abbreviated (using Form B)
5) Brief work force
6) Detailed Mento factors
This system makes it possible to determine the work factor time for manual tasks by the use of predetermined time data. First, a detailed analysis of each task is made, based on the identification of the four major variables of work and the use of work factors as a unit of measure.
Then the proper standard tome from the tables is applied to each motion. The total may be increased by personal, fatigue and delay allowances.
Four Major Variables:
There are four major variables which affect the time to perform manual motions
1) Body member used
2) Distance moved ( inches)
3) Manual control required
4) Weight or resistance involved
Standard Elements of work:
Work Factor recognizes the following standard elements of work:
1) Transport (Reach & Move) (TRP)
2) Grasp (GR)
4) Assembly (ASY)
5) Use (manual, process , or machine time( (US)
6) Disassemble (DSY)
7) Mental Process (MP)
8) Release (RL