CHAPTER VIIIMAKING ADJUSTMENTS: HOW PRESENT PRACTICE IS DEVELOPED INTO STANDARD PRACTICE
In order to make plain exactly how changes are made and take place from the condition before analysis, measurement, and synthesis are made to the standard method of doing the work, we shall take a concrete example and consider it from every phase. This concrete example will be the assembly of a braider or machine for manufacturing braid, which is a standard product of the New England Butt Company. With the co-operation ofMr.John G. Aldrich, who has since become president of the company, the problem of assembling a braider was studied, both in the laboratory and in the shop.
It is not generally recognized that ultimate standards can best be derived in the research room and laboratory. The standard practice inthe plant will be the result of the laboratory practice. If the finer measurements are made in the shop during the general working operations, much time will be lost, as shop conditions cannot be controlled as laboratory conditions can. It has been said that laboratory experimentation is not directly available in shop practice, because laboratory conditions differ from shop conditions. They certainly do differ, but so do the ultimate shop conditions that must be introduced with the new standard method. The ultimate conditions in the shop are far nearer the laboratory conditions than are the shop conditions prior to installation of the new methods.
The method of assembly in use before the motion study and fatigue study were applied was as follows: The base of the braider was placed on an ordinary low bench, and the various parts were kept in tote boxes or on the floor. The worker selected such parts as he wished, and put the braider together according to any traditional method that he had learned, together with such changes as his whims dictated.
All of the previous assembly methods had been determined by the usual practice of putting braider partstogether. In the present case the braider was taken apart; that is, handled in the reverse order of assembly, in order to determine from a new viewpoint the best method of putting the various parts together. The parts were laid out on a table in the sequence in which they were disassembled. This allowed the various members of the braider divisions, groups, and sub-groups to be studied in relation to one another and also separately.
The problem resolved itself into two parts:
1. To make the table of the most convenient height and shape to hold tools and the base group as it grew, while being assembled.2. To provide the most convenient, temporary, resting place for the tools and the various parts, before they were carried to the final position of assembly.
1. To make the table of the most convenient height and shape to hold tools and the base group as it grew, while being assembled.
2. To provide the most convenient, temporary, resting place for the tools and the various parts, before they were carried to the final position of assembly.
The two parts were so closely related that anymodification in one demanded a modification in the other.
Fig 25 - Easel for simplifying motions and reducing fatigue
Fig.25Easel for simplifying motions and reducing fatigue from work of assembly. The obvious sequence in our packet method eliminates the delay and fatigue of the decision of choice.
Fig 26 - rigging on a typical Gilbreth packet
Fig.26The rigging on a typical Gilbreth packet, as used for the assembly of braiders and cord machines at the New England Butt Company. This picture shows only the supporting devices. The length of the supporting devices is determined by what is to be held upon them. The right quantity of each kind, therefore, can be put on without counting. These devices are standardized and are but few in number. They are specially designed and arranged for picking up parts with both hands, simultaneously, in an obvious sequence with shortest motions and least fatigue.
It became apparent, as the work progressed, that the determining elements were (1) to shorten, as far as possible, the distance for transporting the arms and hands while loaded; (2) to arrange the parts so that their sequence of use would be obvious; (3) to position each piece so that it could be grasped, transported, and released in the shortest time with the least expenditure of effort and with the least resulting fatigue. This meant that the parts should be arranged on some sort of a holder, or packet, that would shorten the transporting distance, and that the base group should be placed upon a table that would carry it as near this packet as possible.
A packet, which was practically a table with its top extending vertically, was placed near the table supporting the base group, and removable wire rods of the right length were placed in it to support the various pieces in the best position forgrasping. This also considered the shortest distance for transporting the arms and hands, whether empty or loaded. These table packets were then modified, following closely the principles of the design of the brick packet, especially the hand-hole feature for firm grasping with one motion and for quick counting of the number of pieces. The packets now consist of strips of wood two inches apart, horizontally, and two inches apart, vertically, with holes for pins, interchangeable wire rods, forked hooks, and other hangers, including interchangeable platforms, shelves, and vertical supports, extended and positioned for still shorter reach, and holding in turn such devices as pins to permit the best position for handful grasping without disturbing the motions of the hand or the wrist from the natural position, or, that is, the position most resembling that of normal rest.
The right position for grasping anything with least fatigue is that position that will permit grasping without turning, twisting, or holding the wrist at all from its natural resting position, that is, with muscles in natural balance. It is but natural that this should be the best way, forit cuts out the positioning motions of the hand prior to grasping.
Two reasons that the strips of wood were made two inches apart, horizontally, and two inches apart, vertically, were:
1. Because we desired to get standard data at the same time comparable with our other standard data. We might also use it for checking, by means of motions in another trade, the underlying laws of motions, which we had already deduced in several other trades.2. Because we desired to have the motions in very nearly the same places every time, in order to get the extra efficiency and the lesser fatigue that come from the habit that is formed in this reaching and grasping.
1. Because we desired to get standard data at the same time comparable with our other standard data. We might also use it for checking, by means of motions in another trade, the underlying laws of motions, which we had already deduced in several other trades.
2. Because we desired to have the motions in very nearly the same places every time, in order to get the extra efficiency and the lesser fatigue that come from the habit that is formed in this reaching and grasping.
Many of these laws have since been re-checked and used in methods of least waste for the transference of skill from one trade to another. Habits have been formed that permit a much greater amount of output with less fatigue.
This latticed packet gives us the same dimensions as our cross-sectioned background. We usefour inches in our American work, and ten centimetres in our European work for these distances—the difference between ten centimetres and four inches being almost exactly one-sixteenth of an inch, or so small a difference as to be practically negligible in work on motion study.
This cross-sectioned packet has, therefore, not only many mechanical benefits, such as forming supports, either horizontally or vertically for hangers, but it is also cheap to build, light in weight, and forms an excellent, relative scale for measurement and for “recording the surrounding conditions” of a case of micromotion study.
In fatigue study, as in all other work of investigation, it is difficult to obtain assistants who can “observe what they can see.” Of those observers who observe what they can see, few will write down what they observe. Of those rare ones who can observe and will always write down, few have the habit of maintaining the standard conditions in a long series of observations. We therefore cross-section the background, make our devices, when possible, multiples of four inches, and record the conditions by means of photography,that gives us the key to causes of deviation from class results.
The modification of the table consisted of making it of such a design that it could be turned over on its side to form a low table for tall or double-deck braiders, that would permit motions of less fatigue.
Fig 27 - arrangement of parts for the base group of the braider
Fig 28 - arrangement of parts for the base group of the braider
Fig.27 and 28
This picture shows the arrangement of parts for the base group of the braider. It will be noticed that there are three adjustable shelves, two vertical and one horizontal, for the support in a more convenient position of certain parts that have to be picked up, for least fatigue, by handfuls at a time. The various kinds of shelves, clamps, and tables for different sizes or kinds of machines can be removed or attached to the packet with one motion of the hand.
Note that the top plate is in position and that the tools are at the right side of this top plate before the assembler is sent to the job at all. These parts are arranged in an obvious sequence, and a photograph similar to this is given to the boy whose duty it is to arrange these parts.
In its final form the method consisted of having the parts of the braider placed on the packet by an unskilled laborer or boy, putting large tacks on the floor, which located the table at the most convenient point possible in relation to the packet, which was made fast to the wall or of easel type, on casters, as the position where it must stand demanded. In addition, a small gravity, Johnson-Littlefield packet was attached to the table. This conveyed certain parts, by their own weight, to a yet more convenient position.[6]
Through this adjustment the assembler used only his most skilled motions in doing his work. Meantime, the less skilled worker, or apprentice, who was loading the packet, was learning the assembly principle, and receiving an apprenticeship in assembly itself.
The effect of the adjustment was to establish easily and quickly a new set of efficient habits. The parts being arranged on the packet in an obvious sequence, and the tools being arranged on the table in the standard position, the worker necessarily performed the work according to the standard method, which was the quickest and least fatiguing method, every time that he did it. The result improved his working method, and acted as an incentive to him to do the largest quantity of work of the best quality that could be done with a reasonable amount of fatigue.
This example is even more valuable as a method of attack in the adjustment problem thanit is as a specific illustration of a successful and rapid installation. The workers enjoyed the changes and accepted them in the best spirit of co-operation. Before using the method, eighteen braider base groups had been a large day’s work, per man. With the new method, sixty-six, per man, per day, were assembled with no added fatigue. The resulting saving pleased every one concerned, and has assured the maintenance of the method. Like all other methods, old or new, it must be submitted to certain definite tests. These it has passed with credit. The outlining of such tests is our next problem.
Fig 29 - Littlefield-Johnson carrier packet
Fig.29
This picture shows a Littlefield-Johnson carrier packet. In this carrier packet the carriers by their own weight travel downward to a standard position at the bottom for grasping without looking at them, as fast as they are individually removed. This packet was invented by two men in the New England Butt Company, after they had seen our method of attack, and had begun to think of their work in the terms of elementary and least fatiguing motions.
Fig 30 - Gilbreth packet and a Gilbreth bench
Fig.30
This picture shows a Gilbreth packet and a Gilbreth bench, arranged with the carrier packet shown inFig.29 for the assembly of a 13-strand braider.
The problem of adjustment and its solution can best be illustrated by a concrete example. This is of changes made in assembling the base group of a braider. This example is valuable not only as an incidence of successful application, but as an outline of an efficient working method.
FOOTNOTES:[6]The Johnson-Littlefield packet is a splendid example of the types of fatigue saving devices that are suggested by employees after they have been taught the underlying principles of motion study.
[6]The Johnson-Littlefield packet is a splendid example of the types of fatigue saving devices that are suggested by employees after they have been taught the underlying principles of motion study.
[6]The Johnson-Littlefield packet is a splendid example of the types of fatigue saving devices that are suggested by employees after they have been taught the underlying principles of motion study.