There are a number of principles concerning the economy of movements which form the basis for improved methods at the workplace.
Three aspects are evident:
- Use of human body;
- Arrangement of the work place;
- Design of tools and equipment.
The following ideas are suitable in the office as well as the workshop, and although not universally applicable, form the basis for improving both efficiency and effectiveness, and also effecting the reduction of fatigue.
Use of Human Body
- The two hands should begin and complete their movements at the same time and should only be idle during rest periods;
- Motions of the arms should be simultaneous, symmetrical and in opposite directions;
- The motion sequence which employs the fewest basic divisions of accomplishment is the best for performing a specific task;
- All motions should be made at the lowest classification at which it is possible to do the work satisfactorily, (see below), and hands should be relieved of work which can be done by other parts of the body;
- The work should be arranged to permit an easy and natural rhythm, which is essential to automatic performance.
Classification of Movements
Class Pivot Body Members Moved 1 Knuckle Finger 2 Wrist Hand & Fingers 3 Elbow Forearm, Hand & Fingers 4 Shoulder Upper Arm, Forearm, Hand & Fingers 5 Trunk Torso, Upper Arm, Forearm, Hand & Fingers
Arrangement of the Work Place
- Tools and materials should be pre-positioned at fixed stations within the maximum working area to reduce searching and permit habit formation;
- Gravity feed, bins and containers should be used to deliver the materials as close to the point of use as possible;
- Materials and tools should be arranged to permit the best sequence of motions. 'Drop deliveries' or ejectors should be used wherever possible so that the operator does not have to use his hands to dispose of finished work;
- Provision should be made for adequate lighting, and a chair of the type and height to permit good posture should be provided. The height of the work place and seat should be arranged to allow alternate sitting and standing;
- The colour of the work place should contrast with that of the work and thus reduce eye fatigue.
Design of Tools and Equipment
- The hands should be relieved of all work of 'holding' the work piece where this can be facilitated by a jig, fixture, or foot operated device;
- Two or more tools should be combined wherever possible;
- Where each finger performs some specific movement, as in typewriting, the load should be distributed in accordance with the inherent capacities of the fingers;
- Handles such as those on cranks and large screwdrivers should be designed so as to permit as much of the surface of the hand as possible to come into contact with the handle. This is especially necessary when considerable force has to be used on the handle;
- Levers, crossbars, handwheels and other machine controls should be so placed that the operator can use them with the least change in mechanical position and to the greatest mechanical advantage.