This article throws light upon the top three commercial PMTS (Predetermined Motion Time Standard) which are basically used in industries. The PMTS are: 1. Work Factors System 2. Method Time Measurement (MTM) Basic Motion Time Study (BMTS).
PMTS # 1. Work Factors System:
It is a very versatile concept of having a catalogue of manual motion times and mental process times arranged in such a way that an appropriate time can be obtained from every manual motion likely to be found in any work situation.
Work factor system has ‘8’ types of standard elements which are:
(i) Transport (T)
ADVERTISEMENTS:
(ii) Preposition (PP)
(iii) Grasp (G)
(iv) Use (U)
(v) Assembly (ASY)
ADVERTISEMENTS:
(vi) Disassembly (DSY)
(vii) Mental process (MP)
(viii) Release (RL)
Procedure to calculate operation time by work factor system:
ADVERTISEMENTS:
Following are the procedural steps:
(i) Analyze the job in detail by breaking it into individual motions.
(ii) Determine the number of work factors associated with each motion
(iii) Find the time for each motion from the given tables.
ADVERTISEMENTS:
(iv) Add the times for each motion.
(v) Add the appropriate allowances to get the standard time.
In this system, there are four major variables which affect the time required to perform an operation.
There are:
ADVERTISEMENTS:
(I) Body Members Used:
Following are the body members used to perform the motion:
(i) Arm (A)
(ii) Legs (L)
(iii) Trunk (T)
(iv) Foot (FT)
(v) Finger (F)
(vi) Head Turn (HT), etc.
(II) Distance Moved:
Distances moved measured in inches or cms.
(III) Weight or Resistance:
Weights are always associated with motions and the resistance is experienced by a limb in performing a motion are properly accounted for W.F. system.
(IV) Manual Control:
These reflects the difficulties involved in a motion, these are:
(i) Directional control (steer) – [S]
(ii) Change of Direction – [U]
(iii) Precaution or care – [P]
(iv) Definite stop – [D]
Advantages of Work-Factor System:
Following are the main advantages of work-factor system:
(i) It is simple and easier.
(ii) Quicker work measurement.
(iii) Elimination of use of stop-watch.
(iv) Precise description of jobs.
(v) Elimination of inconsistencies in judgment of speed and effort rating.
PMTS # 2. Method Time Measurement (MTM):
MTM (Method Time Measurement) was developed from motion picture camera study. This is a procedure which analyse any manual operation or method into the basic motions required to perform it and assigns to each motion a predetermined time by the nature of motion and the conditions under which it is performed. The motion time datas measured in the Time Measurement Unit (MTU).
1 MTU = 0.0006 minutes
In this procedure all motions of a operation have been identified, classified and recorded by using time values for each motion from the MTM data. The sum of these motion times gives the time which an average operator would take to perform the task. Standard time can be calculated by adding proper allowances.
In this system, motions are classified in the following categories:
(i) Reach (R)
(ii) Move (M)
(iii) Apply pressure (AP)
(iv) Turn (T)
(v) Grasp (G)
(vi) Position (P)
(vii) Release load (RL)
(viii) Eye times
(ix) Body, Legs and Foot motions.
PMTS # 3. Basic Motion Time Study (BMTS):
In this system basic motion is defined as “Any motion which starts from rest, moves through space and ends at rest.”
Under this system, the body motions are classified as – finger, hand and arm motions, body and leg motions and miscellaneous body motions. Depending upon the nature of muscular control required, there are three classes of finger, hand and arm motions.
These are:
(I) Class ‘A’ motion:
A motion that is stopped by impact with a solid object. Such a motion requires no muscular effort for stopping.
(II) Class ‘B’ motion:
A motion that is stopped by the force.
(Ill) Class ‘C’ motion:
A motion that is stopped by grasping or placing an object by using muscular force. Muscular effort is also used to slow down the motion.
Factors affecting Motion Time:
(a) Distance moved,
(b) Visual attention,
(c) Precision required,
(d) Weight or resistance, and
(e) Simultaneous arm motions.