Principles of Motion Economy as related to the work place

There should be a definite and fixed place for all tools and materials. The operator should always be able to find the tools and materials in the same location. Similarly finished parts and assembled units should be disposed of in fixed places. It should not be that the operator will have to think where the materials are located. Definite stations for materials and tools aid the worker in habit formation, permitting the rapid development of automation.

Tools, materials, and controls should, be located close to the point of use.

Very frequently the work place such as a bench machine desk or table is land out with the tools and materials in straight lines. This is incorrect, for a person naturally works in areas bounded by lines which are arcs.

Normal Working Area:

Considering the horizontal plane, there is a very definite and limited area which the worker can use with a normal expenditure of effort. The normal working area for the right hand is determined by an arc drawn with a sweep of the right hand across the table. The forearm only is extended, and the upper arm hangs at the side of the body in a natural position until it tends to swing away as the hand moves toward the outer part of the work place. The normal working area for the left hand is determined in a similar manner. The normal arcs drawn with the right and left hands will cross each other at a point in front of the worker. The overlapping area constitutes a zone in which two handed work may be done most conveniently.

Maximum Working Area:

There is a maximum working area for the right hand and for the left hand, working separately and for both hands working together.

The maximum working area for the right hand is determined by an arc drawn with a sweep of the right hand across the table, with the arm pivoted at the right shoulder (similarly for left hand). The overlapping area formed by these curves constitutes a zone beyond which two handed work cannot be performed without causing considerable disturbance of posture and accompanied by excessive fatigue.

Each Hand has its normal and maximum working area in vertical plane.

The use of duplicate fixtures and duplicate bins arranged symmetrically on each side of the fixtures permits the two hands to make simultaneous motions in opposite directions in performing the operations. Such an arrangement facilitates natural, easy, rhythmical movements of the arm.

Those tools and parts that must be handled several times during an operation should be located closer to the fixture of working position than tools or parts that are handled but once.

Arrangement of machines: The following statement might be considered as a corollary to rule.

In the continuous type of manufacturing, machines, process apparatus, and equipment should be arranged so as to require the least movement on the part of the operator.

Gravity feed bins and containers should be used to deliver material close to the point of use.

A bin with sloping bottom permits the material to be fed to the front by gravity thereby relieving the operator of having to dip down into the container to grasp parts.

Drop deliveries should be used wherever possible.

The work should be arranged so that the finished units may be disposed of by releasing them in the position in which they are completed, thus delivering them by gravity. This saves time and also frees the two hands to begin another cycle. If a chute is used to carry the finished parts away, it should be located so that the parts can be released in the position in which they are finished.

Materials and tools should be located to permit the best sequence of motions:

The material required at the beginning of a cycle should be placed next to the point of release of the finished piece in the preceding cycle. This arrangement permits the use of two hands to best advantage at the beginning of the new cycle.

Provisions should be made for adequate conditions for seeing. Good illumination is the first requirement for satisfactory visual perception.

By adequate illumination is meant,

Light of sufficient intensity for the particular task.
Light of proper color and without glare.
Light coming from the right direction.
The height of the work place and the chair should preferably be arranged so that alternate sitting and standing at work are easily possible.

Workers should be permitted to vary their positions by either sitting or standing as they prefer. Such an arrangement enables an individual to rest certain sets of muscles and a change in position tends to improve the circulation.

It also produces less fatigue. To determine the average height of the workplace, the height of the worker’s elbow above the standing surface is commonly taken.

A chair of the type and height to permit good posture should be provided for every worker.

A good chair should have the following features. The chair should be adjustable in height. It should be rigidly built, preferable of steel frame, with a lightly padded set and back rest. The edges of the seat and back should be rounded so that no sharp, corners are present.

Swivel chairs and chairs with casters are not readily recommended for factory work unless the operator needs to work through an arc or move about.

Foot Rest: An adjustable foot rest should be provided wherever possible. It may be attached to the floor or to the work table.

Arm Rest: Arm rests are most effective on work that requires little movement of the forearms, with the hands working at approximately the same position, e.g. light drilling, tapping and reaming.

The arm rest should be padded and must not interfere with the necessary working movement of arms and hands.