MOTION ECONOMY AND WORK EFFICIENCY
Most workers do not enjoy making unnecessary or wasted motions, particularly if they result in unnecessary fatigue. In addition to providing some social and psychological rewards, a job should be reasonably efficient Motion study helps to reduce fatigue and waste motions.
Principles of Motion economy
The rules of motion economy and efficiency which referred to hand motions of operators were developed by Gilbreths. The principles of motion economy are divided into three groups, namely:
(i) Effective use of the operator
(ii) Arrangement of the workplace
(iii) Tools and equipment.
Lists below are twenty-two principles of motion economy as developed by Barnes
A. Rules concerning use of human body,
1. The two hands should begin as well as complete their motion at the same time.
2. The two hands should not be idle at the same time except during rest periods.
3. Motions of the arms should be made in opposite and symmetrical direction, and should be made simultaneously.
4. Hand and body motions should be confined to the lowest classification with which it is possible to perform the work satisfactorily.
5. The ascending order of motion classification is:
(a) Fingers only
(b) Fingers and wrists.
(c) Fingers, wrists and lower arms.
(d) Fingers, wrists, lower and upper arms.
(e) Hands, arms and body.
6. Momentum should be employed to assist the worker wherever possible, and it should be reduced to a minimum if it must be overcome by muscular effort.
7. Smooth, continuous curved motions of the hands are preferable to straight line motions involving sudden and sharp changes in direction.
8. Ballistic movements are faster, easier and more accurate than restricted or controlled movements.
9. Work should be arranged to permit easy and natural rhythm wherever possible.
10. Eye fixation should be as free and as close together as possible.
B. Rules concerning arrangement of the work place
1. There should be a definite and fixed place for all tools and materials.
2. Tools, materials and controls should be located close to the point of use.
3. Gravity feed bins and containers should be used to deliver material close to the point of use.
4. Drop deliveries should be used wherever possible.
5. Materials and tools should be located to permit the best sequence of motions.
6. Provisions should be made for adequate conditions for seeing. Good illumination is the first requirement for satisfactory visual perception.
7. The height of the work place and the chair should preferably be arranged so that alternate sitting and standing at work are easily possible.
8. A chair of the type and height to permit good posture should be provided for every worker.
C. Rules concerning the design of tools and equipment
1. The hands should be relieved of all work that can be done more advantageously by a jig, a fixture or a foot-operated device.
2. Two or more tools should be combined wherever possible.
3. Tools and materials should be pre-positioned whenever possible.
4. Where each finger performs some specific movement such as in type-writing, the load should be distributed in accordance with the inherent capacities of the fingers.
5. Levers, cross bars, and hand wheels, which should be located in such positions that the operator can manipulate them with the least change in body position and with the greatest mechanical advantage.
6. Through the application of the principles of motion economy, it is possible to greatly increase the output of manual labor with a minimum of fatigue.
Memo motion Study
Memo Motion study is a special form of micro-motion study in which motion pictures are taken at slow speed using a motion picture camera. Sixty frames per minute and one hundred frames per minute are most common.
Memo motion study has been used frequently to study the flow and handling of materials, new activities and multi-man-and machine relationships and activities of department store clerk. In addition to all the advantages of micro-motion study, it can be used at relatively low film cost and permit rapid visual review of long sequences of activities.
This technique is not usable unless the work is restricted to a general area which can be covered by a motion picture camera. If the person under observation moves from place to place, it could be difficult to use this study.