Analysis of Purpose of Operation
In beginning the analysis of any industrial operation, the very first point that should be considered is the purpose of the operation. Why is the operation being performed?
In a number of instances where the authors (Maynard) have directed detailed studies of the operations performed on mass-production jobs, they have found that from 10 to 35 per cent of the operations were unnecessary.
In view of this experience, therefore, the logical point at which to begin an operation study lies in a consideration of the purpose of the operation.
Unnecessary Operations in Industry.
The reasons that unnecessary operations are performed in industry are several. In the first place, even the most standardized product at one time passed through the development stage. At the outset, the designer was the only one in all probability who thoroughly understood the product. When manufacture was begun, he had to tell the shop what was wanted through the medium of drawings and written and verbal instructions. This is not easy to do. No matter how clearly information is prepared, there are always questions that arise. Every designer has been called upon again and again to explain points that are clearly portrayed on his drawings. It requires a definite period of cutting and trying and developing before all the so-called "bugs" are worked out.
During this development stage, the operations by which the product is to be made are being devised. The operations are performed on a sort of hand-to-mouth basis; that is, one operation is performed before the next is considered. Even if an attempt is made to lay out in advance the proper sequence of operations on new work in the planning or methods department, difficulties are likely to develop in the shop that make changes necessary. The design may be changed, or the material, or the operations themselves as trouble is encountered.
As a result of this development condition, it is small wonder that the process is finally set up with certain unnecessary operations. These operations may have seemed necessary at one time, but owing to changes or development they are no longer necessary. Nevertheless, they are performed and are likely to continue in effect until, after the process has been reduced to a standard routine, someone with the questioning attitude comes along and begins an investigation.
After the initial-development state has been passed, manufacturing troubles are by no means over. A process may run smoothly for a number of months, and then suddenly a difficulty is encountered. The difficulty, of course, must be corrected immediately, and it is often much quicker to add an extra operation than to investigate the causes of the difficulty. If the operation corrects or seemingly corrects the difficulty, it soon becomes a standard operation, even if the causes of the difficulty disappear or are otherwise eliminated, and thus another unnecessary operation is born.
The difficulties referred to may be several. A shipment of poor or improperly prepared material may cause difficulties that can be eliminated only by extra work. The extra work may develop into a standard operation, even though good material is received in the future. If the product is an assembly, it may suddenly start to function improperly on test. If it is at all complicated, it may be difficult to determine just what the causes of the unsatisfactory performance are. Extra operations are added to overcome this or that supposed difficulty. When the product begins to function again, it is not always clear which operation corrected the difficulty and some or all are retained.
Those who are responsible for setting up manufacturing processes are no more infallible than other men. In the judgment of a certain individual, an operation may seem necessary, and he orders it to be performed. Regardless of the soundness of his judgment, the operation will continue to be performed until someone proves it to be unnecessary.
Again, certain operations are performed because of the snap judgment of someone who has the authority to enforce his decisions. Again and again, operations are discovered that are performed because an executive of the company in walking through the shop saw something of which he did not approve and at once issued orders that were followed ever since. When various department heads meet to consider a customer's complaint that may seem serious at the time, extra work may be insisted upon by the sales department and agreed to by the manufacturing department for reasons of policy. The cases of unnecessary work caused in this way are too numerous to attempt to list completely.
In the final analysis, unnecessary operations are due primarily to a lack of thorough investigation at the time the operations are first set up or to a natural inertia or an oversight that keeps operations in effect after changes have rendered them unnecessary. Detailed, searching analysis is needed to reveal these conditions, and it is this kind of investigation that methods studies bring. about.
It should be recognized, of course, that operations rendered unnecessary by new developments, inventions, improved machinery, and the like, are not being referred to here.
It is important to consider the purpose of the operation, but the mere question "What is the purpose of the operation?", mentally framed, may not be suggestive enough to develop a thorough understanding of the matter. If one approaches the supervisor in charge of the operation and asks the question, one will get an answer, of course, and usually the answer will appear logical on the surface. It is not until one begins to search and probe more deeply that the real answer is obtained. For this reason, questions similar to those contained in the following list should be asked. Further, they should be answered only after mature consideration, if the true answer is to be obtained.
1. What is the purpose of the operation?
2. Is the result accomplished by the operation necessary?
3. If so, what makes it necessary?
4. Was the operation established to correct a difficulty experienced in the final assembly?
5. If so, did it really correct it?
6. Is the operation necessary because of the improper performance of a previous operation?
7. Was the operation established to correct a condition that has since been corrected otherwise?
8. If the operation is done to improve appearance, is the added cost justified by added salability?
9. Can the purpose of the operation be accomplished better in any other way?
10. Can the supplier of the material perform the operation more economically?
In a plant manufacturing frames for automobiles, the last operation before painting consisted of reaming certain holes which had previously been punched in the frame. Two operators equipped with air-driven reamers stood at the end of the assembly line and reamed the holes as the frames passed them on a chain conveyer. It was a full-time job for both men and had been for several months.
During the course of a study of frame-manufacturing methods, the purpose of this operation was questioned. The thought at first was that it might be possible to punch the holes sufficiently closely to size to eliminate the reaming operation. Reference to the drawing, however, showed that the customer demanded reamed holes.
It would have been natural, perhaps, to consider that the question "Is the operation necessary? " was satisfactorily answered by the drawing. One of the methods efficiency engineers in the plant, however, realized the danger of accepting the first answer that came to hand and decided to investigate more thoroughly. He went out on the plant parking lot and located a car of the model that used the frame in question. To find the ultimate purpose of the reaming operation, he crawled underneath the car to see what the holes were used for and discovered that they were not used at all. Obviously, then, not only the reaming but also the punching of the holes was unnecessary.
Subsequent investigation showed that at one time an engineering change in the construction of the frame had been made which eliminated the use of the holes. Through an oversight, the drawing was not changed, and the reaming operation continued until the time of the investigation.
This incident, besides confirming the fact that errors are made in connection with manufacturing information, illustrates two important points. In .the first place, it shows the necessity of constantly questioning the purpose of operations. The reaming operation was performed day after day for a number of months.
It would be entirely natural to assume that the operation was necessary just because it had been done so long. Unless a man is trained to question every factor connected with the manufacturing process he is studying, he is likely to accept familiar operations as necessary and to concentrate upon better tools or methods for doing the operations, rather than to attack them from a more fundamental viewpoint,
In the second place, the case illustrates the necessity of applying the questioning attitude with a real desire to get at the bottom of the matter. The asking of a question will nearly always bring forth an answer. The first answer is quite likely to be superficial, however, and more thorough probing is necessary to learn the real facts. Hence, repeated questioning is necessary.
For example, the first question in the above list is "What is the purpose of the operation?" Asked in connection with the reaming operation, the answer is "To make the holes a certain specific size." This might seem to be an answer , but the trained analyst would follow up with the second question on the list, " Is the result accomplished by the operation necessary? " Reference to the drawing apparently evokes an answer in the affirmative. The .basic reason for performing the operation is still not clear, however, so the analyst asks the third question, "If so, what makes it necessary? " His investigation to determine the answer to this question finally uncovers the fact that the operation is absolutely needless.
For many years, it was the practice to polish the edges of the glass windows that go in the doors of automobiles. The reason given was that a good appearance was desired. It is true that edge polishing improves the appearance of a window glass, but only when it is outside the car. When it is assembled, as it is when the customer sees it, only the top edge shows in most designs of window. Hence, three-quarters of the edge-polishing operation is unnecessary. A smooth edge is required so that the window will not mar the channels in which it runs, but a polished edge is a refinement that is in no way justified. This fact was obvious as soon as it was pointed out, but until that time thousands of dollars were spent unnecessarily by a large manufacturer of automobile glass.
In the manufacture of an electric-clock motor, four small pinion shafts were pressed into a bakelite housing. The first shafts received from the supplier went in nicely. On subsequent shipments, however, difficulty was encountered. The shafts had a small burr on the end formed by the cutting-off tool. In order to use the shafts, it was necessary to add the operation "grind burrs."
This condition was taken up with the supplier by letter, but the supplier said that it was impossible to avoid the burr. There the matter rested until a methods efficiency study was made of the operation. Preliminary questioning brought out the above-mentioned story. The analyst, however, was not convinced that the shaft could not be produced without burrs. As a matter of fact, an investigation showed that a similar shaft used for the rotor of the motor was received from a different supplier without burrs. The first supplier was again asked if he could not furnish shafts without burrs, but he again answered in the negative. The analyst then suggested a change of suppliers. This was made, and shafts free from burrs were received thereafter. The first supplier had been too indifferent to attempt to improve his product. The easiest thing to do was to correct the supplier's shortcomings by adding an extra operation. The correct procedure, however, was to persist until satisfactory material was obtained.
A certain metal article manufactured in large quantities required a label of directions. This label was stuck onto the outside of the article. During the course of a study of the product, it was learned that the label was pasted on with flour paste. Several labels were placed face down on a cloth. Paste was applied with a brush, after which the labels were stuck in place. The analyst questioned the use of paste. He was told that gummed labels had been suggested and undoubtedly would be supplied in the future. He examined the labels being used at the time and found that they were coated with gum. Seven operators were engaged in applying paste to gummed labels.
This case illustrates the strength of habit and inertia. The original labels were ungummed. Therefore, paste had to be used. A suggestion was made that gummed labels be substituted. They w^ere accordingly ordered and when the supply of ungummed labels was exhausted the gummed labels were issued. No one but the operators realized, probably, that the new labels had arrived, and they proceeded to apply paste as before either without thinking or in order to appear busy in a department that was facing part-time operation.
A stamping, was made, was formed in a series of punch-press operations. On a certain order, the first two operations were performed on about 5,000 pieces. A rush order for another part was then worked on. The 5,000 partly completed pieces remained in temporary storage in the punch-press department and during that time picked up considerable dirt, including particles from the rush job which was made of metal screen.
As a result, when the job was put back in work again, considerable difficulty was experienced on the third operation. The operator had to wipe each blank clean with a rag before he could put it in his press and, of course, could not meet the regular time allowance. He complained to the time-study engineer who arranged to have a boy wipe the parts clean. The operator could then go ahead without interruption.
About two months later, the time-study engineer found that the parts were still being wiped off between the second and third operations, although the particular dirty lot had long since been completed. When he asked why the operation was being performed, he was informed that he himself had authorized it. The operation was, of course, absolutely unnecessary on subsequent lots, but so strong is the reluctance to abandon an operation after it has once been performed that it was necessary for the time-study engineer specifically to authorize its discontinuance.
If an operation is necessary, it can sometimes be accomplished better in some other way. The pinions on the previously mentioned electric clock contained burrs which in this case could not be eliminated. They were removed by picking them off with a pointed instrument. Tumbling them in a tumbling barrel removed the burrs equally satisfactorily at but a fraction of the former cost.
Occasionally , a consideration of a better way of accomplishing a certain purpose leads to a major design change. For example, the coils used in large turbo generators are made up of a number of turns of heavy strap copper. These are formed on a bending machine and form rectangles some 30 or 40 feet in perimeter. The last three turns of each coil have to be about -^ inch narrower than the other turns to fulfill insulation requirements. Formerly, it was the practice to remove the J-g inch of metal from the last three turns by hand filing, the equivalent of filing a strip of copper 120 feet long for each large coil. Thousands of hours were consumed on this work in the department making the coils. During the course of a methods study, the question was asked, " Can the purpose of the operation be accomplished better in any other way?" The operation was at length eliminated by a design change. The last three turns were made of narrower strap copper and joined to the heavier turns of the coil by a single brazed joint.
The battery cable discussed in Chap. IV was originally purchased in 200-foot lengths. It was made up into leads 49 inches long, and the first operation consisted of cutting the cable into 49-inch lengths. The operation was necessary, of course, but the suggestion was made that the manufacturer of the wire might have a better cutting-off method than the comparatively crude method then in use. Investigation showed that the wiremaking machine could be set to cut off the wire in 49-inch lengths as easily as in 200-foot lengths. Thus the cutoff operation was eliminated, and the wire was obtained in 49-inch lengths at no additional cost.
The examples just given demonstrate the fact that many industrial operations can be eliminated if proper investigation is made, It is much easier to add an operation, however, than it is to eliminate one. Even after an operation has been shown to be unnecessary, it is not always easy to obtain its discontinuance. Habit is strong, and there is a natural tendency to resist change. If a process is working smoothly, there is a decided reluctance to abandon any part of it. It is common experience that operations that are added, almost one might say on the spur of the moment, can be discontinued only after serious discussion on the part of a group of interested supervisors and usually only after someone in a fairly responsible position gives the order and accepts the responsibility.
Thereafter, for a time, the change is likely to be blamed for any difficulty that crops up whether there is any justification for it or not. This is a peculiar condition, perhaps, but one that any progressive shopman encounters again and again. Its existence should therefore be recognized. Resistance to change should be taken as a matter of course, and those who desire to make a change must be prepared to make an effort to get it adopted probably out of all proportion to the effort that would be required if human beings were not human beings.
At the same time, the man who prides himself upon being progressive must be careful that he does not adopt a similar attitude when changes are suggested in his own work that he himself does not initiate.
Full Knol Book - Method Study: Methods Efficiency Engineering - Knol Book
Updated 4 July 2015
First published 23 Nov 2011