Artists' Exhibition on Time and Motion Study - FACT Liverpool 2013

The exhibition is on digital labourers of the modern day.

http://www.furtherfield.org/features/reviews/time-motion-fact-punchcard-protocol-and-creative-capital-our-modern-times

An Enduring Quest: The Story of Purdue Industrial Engineers - Book Information

An Enduring Quest: The Story of Purdue Industrial Engineers

Ferdinand F. Leimkuhler
Purdue University Press, 2009 - Technology & Engineering - 290 pages


The profession of industrial engineering improves the economic efficiency of the technology that drives industrialization.

This book describes how industrial engineering evolved over the past two centuries developing methods and principles for the redesign of production and service systems to make them more economical and efficient. The story focuses on the growth of the discipline at Purdue University where it helped shape the university itself and made substantial contributions to the industrialization of America and the world. The story includes description of prominent industrial engineers like Frank and Lillian Gilbreth, and Charles B. Going.

https://books.google.co.in/books?id=SfJ_FbYtA2IC




Purdue University IE Magazines

Fall 2010
https://engineering.purdue.edu/Engr/AboutUs/News/Publications/EngineeringImpact/2010_2/IE/IMPACT_IE_Fall_2010.pdf 


October 2012
https://engineering.purdue.edu/IE/Spotlights/ie-impact-magazine-focuses-on-rethink-ie/IE%20IMPACT%20Magazine%20-%20October%202012.pdf

Fall  2014
https://engineering.purdue.edu/IE/IEMagazine/ie-magazine/2014%20IE%20Magazine.pdf

What's a Coal Miner to Do?: The Mechanization of Coal Mining

https://books.google.co.in/books?id=km4z1ePwI0oC

The Anatomy of Japanese Business - Kazuo Sato - 11 Essays - Book Information

The Anatomy of Japanese Business


Kazuo Sato
Routledge, 18-Oct-2010 - Business & Economics - 384 pages


This volume collects eleven essays written by Japanese experts on various aspects of Japanese business management and is a sequel to the volume Industry and Business in Japan. It examines the mechanisms for Japan’s phenomenal economic growth since the Second World War by analyzing Japanese management, business groups, production systems and business strategy.


Essay by Taichi Ohno on development of Toyota Production System is there in the book as one essay.

Preview Google Books
https://books.google.co.in/books?hl=en&lr=&id=bY1dBwAAQBAJ

Scientific Management: Frederick Winslow Taylor’s Gift to the World? - 2012 Book Information

Scientific Management: Frederick Winslow Taylor’s Gift to the World?

J.-C. Spender, Hugo Kijne
Springer Science & Business Media, Dec 6, 2012 - 192 pages


Many of those interested in the effect of industry on contemporary life are also interested in Frederick W. Taylor and his work. He was a true character, the stuff of legends, enormously influential and quintessentially American, an award-winning sportsman and mechanical tinkerer as well as a moralizing rationalist and early scientist. But he was also intensely modem, one of the long line of American social reformers exploiting the freedom to present an idiosyncratic version of American democracy, in this case one that began in the industrial workplace. Such as wide net captures an amazing range of critics and questioners as well as supporters. So much is puzzling, ambiguous, unexplained and even secret about Taylor's life that there will be plenty of scope for re-examination, re-interpretation and disagreement for years to come.

There is a surge of fresh interest and new analyses have appeared in recent years (e. g. Wrege, C. & R. Greenwood, 1991 "F. W. Taylor: The father of scientific management", Business One Irwin, Homewood IL; Nelson, D. (Ed. ) 1992 "The mental revolution: Scientific management since Taylor", Ohio State University Press, Columbus OH).

There are other books are under way. The authors offer this additional volume with the hope that it will provoke fresh thought and discussion.
https://books.google.co.in/books?id=WcLkBwAAQBAJ

Operation Analysis - Common Possibilities for Operation Improvement

These common possibilities are indicated by principles of motion economy.

A good analysis of efficiency improvement opportunities has to include examining the 10 efficiency aids.

Gravity Delivery Chutes. 

Gravity delivery chutes are useful for bringing material close to the point of use, thereby shortening the motions required to obtain the material. The usual arrangement consists of a hopper that will hold a reasonable supply of material with an opening at the bottom through which a few pieces may pass. Material may be removed directly from the opening at the bottom of the hopper. If the workplace is crowded, the hopper may be set out of the way and a chute provided between the bottom of the hopper and the point of use along which the parts may slide by gravity.

If parts are of a suitable shape, special delivery devices may be built that are more effective than the common chute. Small, uniform parts with no projections may be handled in an arrange-ment that delivers the parts at the bottom in predetermined quantities. The coin holders used by street-railway conductors, newsboys, and others who must make change frequently are a well-known example of this sort of delivery device.

Many parts are by no means free from projections or even symmetrical in shape. The design of chutes and hoppers that will handle irregular parts is more difficult, and considerable cutting and trying may be necessary before an arrangement can be devised that will deliver parts uniformly at a given point and will neither jam nor overflow. If the chute is used in conjunction with moving machinery, the delivery problem is much easier. Even the smoothest running machine has a certain amount of vibration, and if the chute Is rigidly attached to some part of the machine, the vibration mill cause the parts to move slowly and uniformly down the chute and even around bends.

Illustration:  Chute used in conjunction with a trimming machine for a leather of machine.

As originally designed, the parts tended to jam in the hopper. Removing the key of the jam brought a rush of parts which sometimes overflowed the sides of the chute. The parts did not slide easily, and, therefore, the chute had to be steep. An angle sufficient to overcome starting friction was too steep when the parts were in motion, and the parts shot down so quickly that they were continually falling to the floor. These difficulties were overcome by slight design changes, but principally by attaching the chute to the machine so that the vibration from the machine kept the parts in motion. After this, the parts fed uniformly down the chute and arrived without interruption at a point where they could conveniently be grasped by the operator.

Drop Delivery. 

Drop delivery, as the name implies, consists of getting rid of a part by dropping it. It is used when placing finished parts aside. Sometimes, it is possible to arrange a setup In such a way that the finished part falls off into a container or chute as it Is completed, and the operator does not have to handle it after completing work upon it. For example, after completing the trimming operation on the machine, the operator merely opens his fingers, and the finished part falls into a box placed directly beneath the cutter. On operations where the finished part must be carried aside by the operator, drop delivery is still obtained if the part is carried over a container or a chute and is released by opening the fingers as the hand continues on its way to the next point, which is usually the raw-material supply. Not all parts can be dropped, of course. Fragile, brittle, or soft parts would be damaged if dropped with any appreciable jar. Even with parts of this kind, however, drop delivery can sometimes be used if the parts are dropped onto some sort of soft, yielding surface. A canvas chute may be provided, for example, which first breaks the fall of the part and then permits It to slide gently into a container.

When drop delivery is employed, the relative position of the raw- and the finished-material containers is Important. Many times workplace layouts are encountered In which the raw material Is close to the operator and the finished material farther away. This is Incorrect. The finished material should be closer to the operator and the raw material farther away and in the same line.  When the operator finishes work on a part, he grasps the part. He moves toward the raw-material container and drops the part in the finished-material container on the way. With a little practice, he can do this without hesitation. Finished material is laid aside and raw material is obtained with two motions, one over to the raw-material container and one back to the work point. If the position of the material containers is reversed, three motions will be required, one to the finished-material container where the part is dropped, one to the raw-material container, and one from the raw-material container to the work point.



In order that parts may be dropped during a motion without hesitation, the object into which they are dropped must be large enough so that there is no danger of missing it. If the container itself is small or if the part must pass through a small hole in the bench, a funnel should be provided to make it easy to drop the part in the desired location.

Drop delivery suggests that the part falls away owing to the force of gravity. The same effect may be obtained by the use of springs that carry the released part aside, usually in an upward direction. The most common application of this arrangement is in the suspension of tools above the workplace.  The tools are hung on a "spring. After the tool has been used, it is released by opening the fingers. The spring carries it away without further attention on the part of the operator.

A similar application of this principle may be made to the levers of small hand-operated arbor presses. When the handle of the press is released after the operation has been performed, a spring carries it out of the way and raises the arbor. The hand of the operator at the point of release is thus near the point where it must next go. Instead of some distance away as it would be if the hand had to return the press lever to the aside position.

Methods Used by Two or More Operators. 

 If no detailed instruction has been given, in at least 95 per cent of all cases observed by the authors, different operators on the same job will use different methods, even if the operation is fairly simple. The methods will all resemble each other, to be sure, but the trained observer will be able to detect many minor differences, and it is these differences that account for variations in production, fatigue, and quality of work.

As a matter of fact, where no specific instruction regarding proper methods has been given, it is not uncommon to see the same operator using two or three different methods on the same operation. Questioning fails to reveal the reason for this. Most operators do not seem to realize that they are using different methods. They have not been taught to regard their job as a series of elemental motions, and therefore an extra motion or two may be made without conscious recognition.

On repetitive work, considerable difference is found in the output of different operators doing the same operation. The usual tendency is to attribute this to differences in skill and perhaps effort. In reality, however, the difference is usually primarily due to a difference in method. The high producers have the best methods. These may have been developed as the result of long experience, or they may have  been hit upon the first day on the job. The low producers have poor methods. These operators may be new to the work, or they may be old operators following a poor method from habit.

With proper operator instruction, this condition will not exist. If the best existing method is first recognized and then taught, all operators but the obvious misfits may be raised to the levels of the highest producers.. This can be done by any supervisor who is able to recognize different methods when he sees them and who realizes the difference that minor variations make. If he is sufficiently interested to decide which of several methods is best and to teach that method in detail to each operator in the department, he can raise the performance level of his department within a short time without any outside assistance.

It must be recognized, of course, that it is not always easy to teach operators new methods. Old methods, because of constant repetition, become habitual, and habits are hard to change. Very often, the easiest and best method will seem harder and slower to an operator than his own method. His production will fall off at first, and he will want to return to his own way of doing things. Patience and persistence on the part of both the operator and his instructor will overcome these difficulties, however, and a better performance and higher earnings will eventually result.

Chairs for Industrial Workers.

The subject of chairs for industrial workers has received a good deal of attention, and most progressive concerns have tried to do something along these lines. Interest in the subject is usually not sustained, however, and therefore the analyst often finds room for improvement. Many chairs designed for industrial use have been placed upon the market, some of which are good.

To minimize fatigue, work should be done alternately seated and standing. Although it is less fatiguing to work seated than standing, even the seated position becomes tiring after long periods of time. Therefore, a workplace arrangement that permits the operator to vary his position from time to time is the best from the standpoint of fatigue.

In order to permit the use of the same motions seated or standing, the height of the chair must be such that the elbows of the operator are the same distance from the floor when he is seated as when he stands. The proper height of the workplace should be determined while the operator is standing.

This is the ideal condition, and like many ideals, is difficult to attain under everyday conditions. Operators vary in size which makes adjustable chairs and even adjustable work-station heights necessary- Where two or more shifts use the same equipment, the problem is further complicated. A tall operator may work a given operation on one shift and a short operator on the next. For example, a certain plant operated a large sewing department on a two-shift basis. When the first shift finished work, all the operators were required to leave the department. Then ; after a signal was given, the second-shift operators entered. The first few minutes were occupied by a confused search for suitable chairs. The sewing machines were all the same height from the floor, and so each operator had to search for a chair that was adjusted so that it would enable her to assume a fairly comfortable working position. Considerable time was lost in starting work, and it was not always possible for an operator to find a suitable chair.

Variable conditions of this sort may best be met by providing equipment that is suitable for a certain size range. Chairs may be adjusted for several classes of operators as very short, short, medium, tall, and very taU. If the chairs are marked as to class and the operator is informed of the class to which she belongs, she will have no difficulty in locating a proper chair at the beginning of the shift, provided that a sufficient number of all classes is available.

The height of the workplace is a point that has received too little attention throughout industry. Benches are made to a standard height. Thus, when an operator stands at the bench, if he is short, he stands on a box or a platform if he can get one. If he is tall, he stoops and as a result has an aching back at the end of the day. Conditions of this sort should be corrected wherever found. A slight change in the height of a workplace will often result in more production of a better quality and a more satisfied and less fatigued operator.

An industrial chair, besides being adjustable for height, should have a wide seat from side to side and an adjustable back rest. If, however, the seat is wide from front to back, many operators will sit on the front edge of the chair and will not use the back rest. This apparently is. because, when one is sitting far back on a wide seat, the front edge of the chair presses the underside of the thighs, cutting off circulation from, the feet and legs and causing general discomfort. A tired back seems preferable, and so operators sit on the front edge of their chairs. This condition may be avoided by providing narrow seats not greater than 13 inches from front to back.

Ejectors and Quick-acting Clamps. 

The possibility of improving jigs and fixtures and of providing ejectors, quick-acting clamps, and other time-saving devices should have been considered when the tool equipment was analyzed. The point is so important, however, that it is brought up for consideration again under item 7 of the analysis sheet so that it will not be overlooked. Quick-acting clamps, for example, materially reduce the time required to fix a part in a holding device. Ejectors kick the part out of the holding device and make the removal of the part easier.

Foot-operated Mechanisms. 

Any time that an operation can be performed by parts of the body other than the hands, it should be so done, if there is other work that the hands can perform at the same time. In this way, the hands are relieved of performing certain motions, and time is saved. If, however, there is no other work for the hands to do, there is usually no point in transferring operations to the feet.


The foot-operated drill press is a common example of a foot-operated mechanism. The operator works the drill spindle by a foot pedal, leaving both hands free to place drilled parts aside and to get other parts to be drilled. Foot-operated ejectors are sometimes advantageous, as they leave both hands free to grasp the part as it is ejected. Vises may be opened and closed by foot with a considerable saving of time. When chips or cuttings must be removed from a fixture at the end of an operation, an air jet built into the fixture and controlled by a foot-operated valve may be provided. The possibilities for employing foot-operated mechanisms are many, and the analyst should constantly be on the watch for them.

Two-handed Operation. 

Two-handed setups which permit the use of motions made simultaneously by both arms moving in
opposite directions over symmetrical paths are highly desirable, because they yield far greater output with the same or less expenditure of energy than do setups on which one hand only is able to work effectively.

Although when two-handed setups are once devised they are fairly simple to operate, it requires considerable ingenuity and a thorough understanding of the principles of motion economy to make them correctly. Two-handed-operation setups are usually made only after detailed motion study. The possibility of making such a setup should be considered during the analysis of all operations, however, for throughout the analysis process, the desirability of a subsequent more detailed study must be kept in mind.

Normal Working Area. 

The concept of normal and maximum working areas (a principle of motion economy) has been discussed in under the head of "The Workplace Layout." If the arrangement of tools and material was not considered during the analysis of item 6, it should be studied during the analysis of item 7, for the proper arrangement of the workplace is highly important to effective performance.

Layout Changes and Machine Coupling .

(One operator manning multiple machines) 

As the result of detailed analysis, the possibility of coupling machines may have occurred. Machine coupling or multiple machine operation is possible when the operator is idle during part of the operation cycle, usually because a machine is doing the work without attention on his part. The idle time can often be utilized in running another machine if the second machine is located near the first.

If no machine is available near by, it may be desirable to change the layout and move one or more machines about. It is usually best to avoid making many minor layout changes separately, for if all factors affecting the department as a whole are not considered, the layout is likely to become inefficient. Unless a change is obviously desirable and easy to make, it is better to accumulate suggestions for change until sufficient are at hand to make a detailed layout study advisable.

The possibilities for machine coupling are brought out by man and machine process charts. (discussed in another chapter). Plant layout is a study in itself. Some of the issues in related to making layout studies are described in another chapter.

Utilization of Improvements Developed for Other Jobs. 

Each operation analysis should not be regarded as an entirely new investigation. Many different operations present points of similarity; if a good method has been worked out for one operation, parts of it may often be applied to another.

Full Knol Book - Method Study: Methods Efficiency Engineering - Knol Book


Updated 4 July 2015
First published 24 Nov 2013

The Rules of Work: A Practical Engineering Guide to Ergonomics, Second Edition 2012 - Book Information

The Rules of Work: A Practical Engineering Guide to Ergonomics, Second Edition
Dan MacLeod
CRC Press, Oct 23, 2012 - 196 pages


The experience of the past decade since the publication of the first edition of The Rules of Work: A Practical Engineering Guide to Ergonomics proves just how central ergonomics is for effective production. Revised and updated to reflect new insights from workplace developments, the second edition continues the tradition of providing essential tools for implementing good ergonomics in a way that simultaneously improves both productivity and safety.

https://books.google.co.in/books?id=_fvPqFox1LcC

Analysis of Purpose of Operation

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.

Questions

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?

Typical Answers.

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.

Tfli.Tnitifl.ti.ng Operations.

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

Analysis of Tolerances and Inspection Standards - Methods Efficiency Engineering

Analysis of Tolerances and Inspection Standards

The specification of tolerances or the standards of quality, accuracy, finish, and so on, that the operation must satisfy play an important part in the methods used to produce the part. In fact, in many cases, the requirements fix the method. The accuracy with which the diameter of a small shaft must be machined and the finish which the machined surface must possess will determine the machines that must be used, the number of cuts taken, and the feeds and speeds.

Hence, at the outset of any methods study, it is important, first, that the tolerance requirements of the operation be known and, second, that these requirements be reviewed for correctness.  The assumptions are made that the operator is doing a job which will pass inspection and that the requirements as specified by the designer or the chief inspector are correct. Undoubtedly these assumptions are true in the majority of industrial operations, but enough important exceptions are encountered to make an analysis of tolerance and inspection requirements a point of primary importance.

Questions.

The following questions should be raised and, as always, answered only after careful consideration:

1. What are the inspection requirements of this operation?

2. What are the requirements of the preceding operation?

3. What are the requirements of the following operation?

4. Will changing the requirements of a previous operation make this operation easier to perform?

5. Will changing the requirement of this operation make a subsequent operation easier to perform?

6. Are tolerance, allowance, finish, and other requirements necessary?

7. Are they suitable for the purpose the part has to play in the finished product ?

8. Can the requirements be raised to improve quality without increasing cost?

9. Will lowering the requirements materially reduce costs?

10. Can the quality of the finished product be improved in any way even beyond present requirements?

Relation of Methods Efficiency Study to Quality.

Methods efficiency studies are made primarily for the purpose of eliminating waste and reducing costs. In so doing, however, it goes without saying that nothing should be done to impair the quality of the finished product or its salability. Because the methods efficiency engineer is interested in enhancing the competitive position of his company's products, he quite naturally must take a keen interest in the factor of quality. Products of superior quality outsell products of inferior quality, other things being equal; hence, an improvement in quality is always desirable, provided, of course, that it is necessary and useful quality. Any improvement that betters the functioning, appearance, or salability of the product should be constantly sought. Unnecessary quality, however, refinements that add to the cost of the product without in any way improving it, should be eliminated.

Sometimes it is difficult to decide whether a certain requirement is an unnecessary refinement or a desirable improver of quality. Such questions can be answered only after a thorough discussion of all of the factors involved. In general, however, because of the competitive condition existing in industry, any suggested improvement in quality that can be made without taking the product out of its price class should be adopted.

The methods efficiency engineer is in a good position to make suggestions that will improve quality. Because he studies a product in detail and considers thoroughly every factor connected with it, he is quite likely to discover ways of making the product better. In addition, because he eventually sets up working methods that are easy, efficient methods, and because he trains all operators to follow those methods, a higher and more uniform quality of workmanship results than where each operator is left to develop methods for himself. As a result, therefore, methods study tends to raise the quality of the finished product.

Results of Analyzing Inspection Requirements.

For machine work, the limits of accuracy within which the part must be machined are customarily specified on the drawing of the part. These allowances are worked out by the design engineers and are based upon the function the part is to play in the finished product and the relation of the dimensions of the part to the dimensions of the other parts with which it is used. Theoretically, the allowances established by the design engineers should be correct; but because the human element enters in here as elsewhere, they should be carefully checked by the analyst.

Close tolerances raise the cost of a machining operation by making it necessary for the operator to work accurately, checking his work frequently. More cuts are necessary if dimensions must be held accurately, and perhaps even additional operations on other machines. There is a tendency for designers to specify increasingly close tolerances, a tendency that many shopmen deplore. However, the performance requirements of many products are becoming daily more exacting, and as a result accuracy requirements are likely to become increasingly severe. Machine shops, therefore, must face this problem and learn how to work more and more accurately. That this objective can be attained is evidenced by the remarkable advances being made almost daily in the automotive and aviation industries.

When tolerances are carefully reviewed, some may be found that appear to be unnecessarily close for the function of the part hi the finished apparatus. Such cases should be presented to the engineers with a statement of the amount that may be saved by allowing greater leeway. If the tolerance really is too close and a worth-while saving will be made by increasing it, the change will in all probability be made.

It will aid materially in getting such changes made if charts showing tolerance and related cost are available for different classes of operations. Such charts serve to emphasize clearly how much costs are increased as tolerances are decreased. They can also be of value to design engineers, for reference purposes.

Occasionally, tolerances are not close enough. Sometimes, by tightening the requirements on a machining operation, the assembly is made easier, and the amount spent on the extra machine work is offset or more than offset by the saving made on the assembly floor. In standardized manufacture, fitting during assembly has been practically eliminated. Parts are machined so that they go together without filing, bending, or adjusting. The same condition is desirable in small-quantity production where much fitting is commonly done, and it can often be approached by tightening the accuracy requirements on the principal parts.

When a product is made to sell for a price, as, for example, a certain grade of shoe, the matter of allowed quality becomes extremely important. It is possible to add operations almost indefinitely that will improve quality, but the added cost will take the finished shoe out of its price range. Hence, it becomes necessary to determine what can be done for the amount of money available. In a situation of this kind, labor effectiveness is of paramount importance. The more effectively operations are performed, the more operations can be done. The more operations, the better the quality, and, hence, the better the competitive position of the shoe.

Source: Operation Analysis, Maynard

Full Knol Book - Method Study: Methods Efficiency Engineering - Knol Book


Updated 4 July 2015
First published  23 Nov 2013