Predetermined Motion Time Systems (PMTS)
After reading this article you will learn about:- 1. Meaning of Predetermined Motion Time System (PMTS) 2. Objectives of PMTS 3. Techniques 4. Selection 5. Uses 6. Advantages 7. Limitations.
Meaning of Predetermined Motion Time System (PMTS):
A predetermined motion time system can be defined as a procedure / method that analyzes all the basic or fundamental movements necessary for manual activity / human movement. Each of these motions is given a predetermined standard time value or a previously fixed time value in such a way that the individual motions are used for total time.
PMTS is a tool for estimating work that meets synthetic times. The fact that they are slowly collected more accurately and often used as a source of synthetic time data is more precise and exact than in modern times.
Therefore, PMTS are more common than standard data and are used for manual cycles more generally.
The use of a default time system requires that the measurement is divided into basic movements / motions, as required by the particular system. All programs must be followed exactly by their own particular rules and procedures.
In order to correspond with the company level of performance, the level of performance as reflecting the time standards produced by the system must be determined and adjusted, if a company first adopts a predetermined system.
This is a one-off change, as performance ratings must not be considered further. Time systems are not usually pre-determined so that they are added as they would in a time study.
Predicted time systems can be classified in terms of accuracy, application time and the description of the methods. The systems were initially designed for general use and could be used for most industrial operations. Numerous advanced systems with a simplified version designed to be used for longer operations are now available.
They can be applied more quickly but the results are less precise. There are also functional systems designed for clerical, machine or large-scale use of very small tools. PMTS has been used in a limited manner for many years but is now growing in use since the advantages and disadvantages of such systems have been better understood by the user.
The major advantage of PMTS is that it allows the standard time for an activity / job to be pre-determined if the motion pattern is identified. Through the workplace design and description of the method used, one can find out how long an operation would take beforehand.
The root of PMTS can be traced to the "therblig" as Gilbreth did in the chronocyclography, and the first attempt to establish time by motion length. Therbligs was used in all PMTSs as fundamental motion units.
Thus, a detailed knowledge of the job can be achieved through two-hand process charts. In addition, it is possible to establish the links between two different activities. Different charts are therefore generated and then the principles of motion economics are compared and the best approach is discovered.
Procedure:
(1) Study the complete operation cycle few times.
(2) Observe and record the activities of one hand at a time.
(3) Record only few symbols at a time.
(4) Recording should be started at a point of time that can be easily distinguished. For examples activity of picking up the such work piece at the beginning of cycle of work is a good point from which recording the movements should be started,
(5) Care should be taken that no activity is left while recording, as it\will affect the method study badly.
(6) Combinations of operations and transport should be avoided, unless they actually occur at the same time.
A two hand process chart for nut and bolt assembly is shown in Fig. 18.13.
Objectives of PMTS:
The predetermined lime systems have been successfully applied to:
(i) Identify expectations for working time.
(ii) Compare times for alternative methods so that the economics of the proposals is determined before the production is carried out or otherwise round production / production of equipment to be employed.
(iii) To estimate the workforce, equipment and space requirements before development or deployment.
(iv) Develop provisional layouts for assembly lines before starting work in order to minimize investment in future rearrangements and re-equilibriums, etc.
(v) To improve and modify working methods before specifying the task.
(vi) Set time limits for different jobs.
(vii) To provide a basis for estimating work costs and wage schemes.
(viii) To support employees and control workers to prepare.
(ix) To be used to measure those short and recurring movements that are difficult to measure by stop watch.
Technique /Development of a PMT System:
It consists following steps:
(i) The methodology used to create PMTS data does not calculate element time by stop watch, so as not to introduce inaccuracies by use of human elements.
(ii) All manual work for the industry is assumed to consist of certain fundamental human movements such as movement, reach, involvement or disengagement etc., common in almost all jobs.
(iii) The average time taken to carry out the basic activity / movement by the (normal) industrial workers is almost constant.
Taking into consideration the facts mentioned above, the various steps involved in collecting PMTS data are as follows:
(1) Choose a large number of employees performing different activities or working different jobs in the industrial unit under normal working conditions.
(2) Carry out a micro motion study, which means recording the work on a film.
(3) After the analyzes, record and compile the data as a table, which is the time required to complete each element.
Another argument to be remembered is that the jobs are chosen in such a way that most specific fundamental tasks are involved and are performed by employees of different ages and with different characteristics under different conditions.
Once the tables / charts have been prepared for different basic activities / motions, the normal time can be determined by dividing the job into its main movements, taking into account the time of each move from the chart, and adding the time values for all the basic movements. This can achieve standard time by adding the correct allowances to normal time.
Selection of a Particular PMT System:
The following factors are considered while selecting a particular PMT system for application to a particular industry:
(1) Cost of Installation:
Installation costs are the cost of getting specialists to implement the program under consideration.
(2) Operational Cost:
This is determined by the time it takes for the systems to set a standard.
(3) Level of Performance of the System:
The performance level in the system being considered may differ from the normal performance in the industry to be used. However, the calibration that can resolve this problem is nothing but a multiplication by calibration factor (certain constant) or by applying an adjustment allowance of the times given in the diagrams.
(4) Consistency of Standards:
Consistency of standards established by a system on various jobs will be a key factor to consider. The system can be used on a test basis on a number of industrial unit operations and can be checked for consistency between them.
(5) Nature of Operation:
Best results can be obtained if the type and nature of the operations in the plant match the type and nature of land under research when the system is created.
Uses of PMTS:
The majority of uses are minted and the advantages are explained. Their application is classified under both headings, i.e. working and working methods.
Uses in Work Methods:
(1) Enhancement of existing methods.
(2) Assessment in advance of the current production of the proposed methods.
(3) Assessment of machine design, jigs and machinery, etc.
(4) Assistance in manufacturing design.
(5) Assistance to coaches.
(6) Training staff members to be aware of the movement.
Uses in Work Measurement:
(1) Establishing time standards.
(2) Completion of standard data formulas for certain working classes.
(3) Checking standards established by time study.
(4) Auditing time standards.
(5) Balancing Production lines.
(6) Estimating labour costs.
Advantages of PMTS.:
Predetermined motion time system possesses the following advantages:
(1) There is no time required to remove it in the exactness of the time study for the stop watch.
(2) The implementation of PMT removes the need for alarming and divisive performance ratings. This does not require a performance rating.
(3) Use PMTS, the analyst is conscious of the process and takes a detailed look at the system. This can help improve the process occasionally.
(4) Use PMTS, the analyst is conscious of the process and takes a detailed look at the system. This can help improve the process occasionally.
(5) They are a good technique for preparation.
(6) When an organization's analysts are identified, they can be implemented easily.
(7) Relatively consistent are the basic times when the PMT system is used.
(8) You will arrive at a time level for a job without going to work.
(9) The time and costs of finding the default time for a job are reduced significantly.
Limitations of PMTS:
(1) PMTS can only accommodate service manual movements.
(2) For non-repetitive activities, they are not economic.
(3) They can not be applied to limited work (see time studies for processes).
(4) The fact that PMTS is based on data from specific operations is restrictive in nature and thus PMTS provides better results if only for this type of work/ operation is used.
(5) During collecting PMTS data, all categories of motions were not considered.
(6) The need for qualified staff. Although the PMT system removes the use of ratings, there is still some judgment at various stages.
