Production System Industrial Engineering

Your comments are welcome. The article will be edited multiple times to make it more crisp. Your suggestions will be incorporated. This is an important contribution to Industrial Engineering Thought synthesized from multiple sources created by industrial engineering pioneers and subsequent professors and practitioners like Lowry, Maynard and Stegemerten.

Production System Industrial Engineering - Focus Areas of Industrial Engineering Utilized

Productivity Science  

Taylor - Productivity Science and Art of Metal Cutting - Important Points

https://nraoiekc.blogspot.com/2019/06/taylor-art-of-metal-cutting-important.html

Facilities Industrial Engineering 

https://nraoiekc.blogspot.com/2020/05/facilities-industrial-engineering.html

Product Industrial Engineering
https://nraoiekc.blogspot.com/2012/09/product-design-industrial-engineering.html

Process Industrial Engineering
https://nraoiekc.blogspot.com/2017/02/process-industrial-engineering.html

Human Effort Industrial Engineering
https://nraoiekc.blogspot.com/2017/09/human-effort-industrial-engineering.html

Industrial Engineering Management - Productivity Management
Productivity Management in Engineering Organizations - Online Book
https://nraoiekc.blogspot.com/2019/10/productivity-management-in-engineering.html

In industrial engineering literature, the production system industrial engineering is discussed in good detail in the "Operation Analysis" topic. Operation analysis was used in Westinghouse. Maynard described it in a book. It was a chapter in "Time and Motion Study" authored by Lowry, Maynard and Stegemerten in 1927. Then Maynard and Stegemerten  authored a full book on it in 1939. Niebel described it well in his book Motion and Time Study first published in 1955.

The operation analysis steps include:

Product Design - Specifications and  Tolerances
Materials
Process of Manufacture
Sequence of Operations
Purpose of Operation
Equipment/Machine
Setup and Tools
Plant Layout
Material Handling
Working Conditions
Principles of Motion Economy and Motion Study

Gerald Nadler, cites Marvin Mundel and gives five alternatives for contemplating industrial engineering changes.

Product Design
Material
Sequence of Work or Sequence of Material transformations
Equipment
Hand Pattern or Motions of the Operators

The above steps can be arranged under the four main components of industrial engineering and explained for application in engineering systems productivity improvement. The article now focuses on production but inspection, maintenance, design and such other engineering processes are also improved using a similar structure. Separate articles will be created in the future for each engineering process.

Product Industrial Engineering

Product Design

Industrial engineer should review every design for possible improvements. Designs are not permanent; they can be changed by both product designers and industrial engineers. If  improvement is possible,  the change should be made. Industrial engineer has to initiate an industrial engineering design change project.  Design for manufacture and assembly is now an established subject. But Niebel covered it well in his 1955 book.

To improve the design, the analyst should keep in mind the following pointers for lower-cost designs:

1. Reduce the number of parts, thus simplifying the design.
2. Reduce the number of operations and length of travel in manufacturing by joining parts better and making the machining and assembly easier.
3. Utilize a better material.
4. Rely for accuracy upon “key” operations rather than upon series of closely held limits. These general observances should be kept in mind as consideration is given to design analysis on each component and each subassembly.

The General Electric Company has summarized the following ideas to be kept in mind for developing minimum cost designs: [American Machinist, reference sheets (12th ed.; New York: McGraw-Hill Publishing Co., Inc.).]

Castings
1. Eliminate dry sand (baked-sand) cores.
2. Minimize depth to obtain flatter castings.
3. Use minimum weight consistent with sufficient thickness to cast without chilling.
4. Choose simple forms.
5. Symmetrical forms produce uniform shrinkage.
6. Liberal radii—no sharp corners.
7 . If surfaces are to be accurate with relation to each other, they should be in the same part of the pattern, if possible.
8. Locate parting lines so that they will not affect looks and utility, and need not be ground smooth.
9. Specify multiple patterns instead of single ones.
10. Metal patterns are preferable to wood.
11. Permanent molds instead of metal patterns.

Moldings
1. Eliminate inserts from parts.
Design molds with smallest number of parts.
Use simple shapes.
Locate flash lines so that the flash does not need to be filed and polished.
Minimum weight. :



Punchings
1. Punched parts instead of molded, cast, machined or fabricated parts.
2. “Nestable” punchings to economize on material.
3. Holes requiring accurate relation to each other to be made by the same die.
4. Design to use coil stock.
5. Punchings designed to have minimum sheared length and maximum die strength with fewest die moves.

Formed Parts
1. Drawn parts instead of spun, welded or forged parts.
2. Shallow draws if possible.
3. Liberal radii on corners.
 4. Bent parts instead of drawn.
5. Parts formed of strip or wire instead of punched from sheet.

Fabricated Parts
1. Self-tapping screws instead of standard screws.
Drive pins instead of standard screws.
Rivets instead of screws.
Hollow rivets instead of solid rivets.
Spot or projection welding instead of riveting.
Welding instead of brazing or soldering.
Use die-castings or molded parts instead of fabricated construction requiring several parts.

Machined Parts
1. Use rotary machining processes instead of shaping methods.
2. Use automatic or semi-automatic machining instead of hand-operated.
3. Reduce the number of shoulders.
4. Omit finishes where possible.
5. Use rough finish when satisfactory.
6. Dimension drawings from same point as used by factory in measuring and inspecting.
7. Use centerless grinding instead of between-center grinding. .
8. Avoid tapers and formed contours.
9. Allow a radius or undercut at shoulders.

Screw-Machine Parts 1. Eliminate second operation. 2. Use cold-rolled stock. 3. Design for header instead of screw machine. 4. Use rolled threads instead of cut threads.

Welded Parts
1. Fabricated construction instead of castings or forgings.
Minimum sizes of welds.
Welds made in flat position rather than vertical or overhead.
Eliminate chamfering edges before welding.
Use “burn-outs” (torch-cut contours) instead of machined contours. .
Lay out parts to cut to best advantage from standard rectangular plates and avoid scrap. :
7. Use intermittent instead of continuous weld.
8. Design for circular or straight-line welding to use automatic machines.

Treatments and Finishes
1. Reduce baking time to minimum.
2. Use air drying instead of baking.
3. Use fewer or thinner coats.
4. Eliminate treatments and finishes entirely.

Assemblies
1. Make assemblies simple.
2. Make assemblies progressive.
3. Make only one assembly and eliminate trial assemblies.
4. Make component parts RIGHT in the first place so that fitting and adjusting will not be required in assembly.

This means that drawings must be correct, with proper tolerances, and that parts be made according to drawing.

General
1. Reduce number of parts.
2. Reduce number of operations.
 3. Reduce length of travel in manufacturing.

It is a poor policy to think of any design as being permanent. It is much better to consider that all designs are wrong, and that the only reason they are in effect is because a better design or process has not been dis- covered. One manufacturer always used cast-iron brackets on its motors. An industrial engineer  questioned this design, and this led to the redesign of the bracket, making it from welded sheet steel. Not only was the new design stronger, lighter, and more eye-appealing, but it was less expensive to produce. A similar design improvement was in the construction of conduit boxes. Originally, they were built of cast iron, whereas, the improved design, making a stronger, neater, lighter, and less expensive conduit box, was fabricated from sheet steel. In another instance a brass cam switch used in control equipment was made as a brass die casting. By slightly altering the design, the less expensive process of extruding was utilized. The extruded sections were cut to desired length to produce the cam switch. All the above improvements were brought about by considering a better material in an effort to improve the design.

Attaching nuts were originally arc welded to transformer cases. This proved to be a slow, costly operation. Furthermore, the resulting design had an unsightly appearance due to the overflow and spatter from the arc-welding process. By projection welding nuts to the transformer case, not only were time and money saved but the resulting design had considerably more sales appeal. A similar improvement was brought about by changing from arc welding to spot welding to join mounting brackets to resistor tubes. Another example of design simplification through joining parts better

Improved design of conduit box. New design fabricated from sheet steel. was in the assembly of terminal clips to their mating conductors. It had been the policy to turn the end of the clip up to form a socket. This socket was filled with solder, and the wire conductor was then tinned and inserted in the solder-filled socket and held until the solder solidified.

The above examples are characteristic of the possibilities for improvement when the design of the part is investigated. It is wise to always check the design for improvement because design changes can be valuable. In order to be able to recognize good design, the industrial engineer should have had some training and practical experience in this area. Good designs do not just happen; they are the result of broad experience and creative thinking, tempered with an appreciation of cost.

Designs should never be regarded as being permanent. Experience has shown that practically every design can be improved. The industrial engineer should question the present design in order to determine if it is possible to improve it. He should learn to recognize good design and if he encounters poor design, he should assume the responsibility of making recommendation for the change of design and do an industrial engineering project of changing the design in the desired direction.

(The content needs to be expanded from adding inputs from the current versions of DFMA books and Value Engineering)

VE Analytical Techniques 

Blast, Create and Refine

Blast

To do blast activity, the basic functions to be accomplished by a product or a component are given the focus and alternative products, materials and processes are brought into the picture. These alternatives need not entirely accomplish all the basic functions completely. These alternatives need to qualify on the basis of accomplishing some important part of the function or functions in a very economical manner. The alternatives are in the consideration list even if they can accomplish important part of the function based on some modifications. During this activity, the amount of the function which would be accomplished by the suggested or identified alternatives and the cost involved are ascertained.

Create
Use real creativity to generate alternatives to  improve the ideas of blast stage, to accomplish large part of the required function with accompanying increase in cost. Increase in functions obtained needs to be accounted by increase in cost.

Refine
The solution obtained in create stage is further sifted and refined by adding features which provide further functions and fully accomplish the desired function. Miles stated that this blast, create and refine technique delivered the total function with the same reliability but at a cost of one-half to one-tenth of the original for many components and products.

Utilize vendors’ available functional products

Number of products like special hinges, special rivets, special tapered structural shapes etc. are available to perform various functions from vendors. Available functional products (even though not standard but special) have low costs because the specialty supplier has a sufficient lead in his particular technology and sufficient volume.

But there are interfering factors that prevent engineers from using the available functional products and they design items for their products afresh. Miles identified some of them as lack of knowledge regarding the availability of the items, preference for do-it-ourselves, feeling that boss wants me to design, inhouse design shows our capability thinking, feeling that own designs are proprietary knowledge, problems of search, and feeling that we can improve over a period of time etc.

Miles recommends preparing functional product lists and specially creating lists for items that are not usually bought.

Utilize applicable standards

Miles has written that including in the list of techniques and highlighting it may look silly, but it is a valuable technique in VE application.

The full meaning includes utilization of standard parts, parts of standard products, engineering concepts, manufacturing concepts, manufacturing processes and materials. He also emphasized that where not applicable standard items should not be used.

Get a dollar sign on key tolerances

Tolerances are required to obtain necessary fit or to allow assembly.
But many times tolerances are specified as standard practice and to give the impression of a complete drawing. Tolerances have cost.
For efficient use in value work each tolerance is to subjected to the following questions.
i) What does it cost?
ii) What function does it provide?
If the cost of tolerance is trifling, it did not be analyzed further. But if it is substantial in the process cost, it is to be analyzed.

(This point was given in Maynard Time Study 1940 book also).

 Use real creativity

Creativity is generating alternatives.  Creative people believe that there are many ways of doing a thing. Miles made the observation that many creative people believe there are at least eight ways of doing a thing. They are not satisfied when they find one way.

In value analysis, creativity is to be applied as soon as the function desired is brought out in specifics. The most common obstacle to creative thinking is natural tendency to let judicial thinking work along. It interferes.  What is required is to suspend judicial thinking and let the ideas flow. Creativity is not associated with only complex problems. Even simple things can have creative alternatives. Creativity can be sustained and more alternatives can be generated in a group brainstorming.


TOLERANCES AND SPECIFICATIONS

There is a natural tendency for designers to incorporate more rigid specifications than necessary when developing a product. This is brought about by lack of appreciation for the elements of cost.  The industrial engineer should be versed in the aspects of cost and be fully aware of what unnecessarily close specifications can do to the production cost.  The analyst must be on the alert for too liberal specifications, as well as those that appear too restricted. By closing up a tolerance, it is often possible to facilitate an assembly operation or some other subsequent step. This may be economically sound, even though the time required to perform the present operation has been increased by reducing a manufacturing tolerance.

One manufacturer's drawings called for a .0005” tolerance on a shoulder ring for a DC motor shaft. Original specifications called for a 1.8105” to 18110” tolerance on the inside diameter. It was thought necessary to hold this close tolerance, as the shoulder ring was shrunk on the motor shaft. An investigation revealed that a .003" tolerance was adequate for the shrink fit. The drawing was immediately changed to specify a 1.809” to 1.812" inside diameter. A reaming operation was saved because someone questioned the absolute necessity of a close tolerance.

By investigating tolerances and specifications and taking action when desirable, costs of inspection will be reduced, scrap will be minimized, repair costs diminished, and quality will be kept high.

The industrial engineer, because of his familiarity with shop operations, is in an ideal position to question the tolerances and specifications assigned to a product. He should well understand the additional cost incurred through establishing close tolerances. Frequently, tolerances and specifications can be liberalized so as to decrease unit cost with no detrimental effects on quality. In other instances, tolerances and specifications should be made more rigid in order to facilitate certain manufacturing operations. Occasionally, the method of inspection as well as the inspection procedure can be changed so as to effect savings.

Tolerances and specifications must be investigated carefully by the analyst in order to be assured of a successful operation analysis program.

Sometimes it will be found that the engineer has made the tolerances unnecessarily close for the purpose of the finished product. The industrial engineer should take this up as IE design change project or initiative pointing out that the cost will be unnecessarily high if the close tolerances are adhered to and recommend more appropriate tolerance. A curve that  shows in per cent how the cost increases for an operation as the tolerance decreases can be prepared  to cover all operations such as turning, milling etc.

If the piece is to have one or more subsequent operations performed on it before reaching the finished stage,  the industrial engineer should learn the final requirements. Then, he should study the subsequent operations in order to learn how they fit together as a whole to make up the finished product. He will learn the part played by the particular operation he is about to study in bringing the product toward the finished state.

Knowledge of inspection requirements will also enable the time-study man to be certain that the material or part is delivered to the operator in the proper condition, and that he performs all the necessary, and only the necessary, work upon it.



MATERIAL

One of the first questions an engineer considers when he is designing a new product is, “What material shall I use?” Since the ability to choose the right material is based upon the engineer's knowledge of materials and since it is difficult to choose the correct material because of the great variety of materials available, many times it is possible and practical for industrial engineers  to incorporate a better and more economical material in an existing design. Especially as a continuous engineering improvement exercise carried out by industrial engineers, it is possible at some point in time of the design. There are five considerations that the industrial engineer should keep in mind relative to direct and indirect materials utilized in a process. These are:

Finding a less expensive material.
Finding materials easier to process.
Using materials more economically.
Possible use of salvage materials.
Economical use of supplies and tools. :

A LESS EXPENSIVE MATERIAL

Prices of materials can be compared by making available monthly publications that summarize the approximate cost per pound of steel sheets, bars, and plates, and the cost of cast iron, cast steel, cast aluminum, cast bronze, and other basic materials  to all engineers. These costs can be used as anchor points from which one can judge the application of new materials. Developments of new processes for producing and refining materials are continuously taking place. Thus, the material prices keep changing and a material that was not competitive in price yesterday may be so today.

-----------------------
2019 Example of New Material at Affordable Price

Once thought too expensive, an innovative Japanese bio-materials company is changing the world with affordable synthetic proteins inspired by spider silk.

https://www.fibre2fashion.com/news/apparel-news/japanese-firms-make-jacket-with-synthetic-protein-textile-251642-newsdetails.htm
https://synbiobeta.com/spibers-biomaterials-stack-from-new-production-facility-to-fashion-runway/
https://synbiobeta.com/along-came-spiber-how-synthetic-proteins-are-weaving-a-new-era-in-materials/
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In one company, micarta spacer bars were used between windings of transformer coils. They were placed so as to separate the windings and permit circulation of air between the windings. An investigation revealed that glass tubing could be substituted for the micarta bars at a saving. Not only was the glass tubing less expensive, but it met service requirements better because the glass could withstand higher temperatures. Furthermore, the hollow tubing permitted more air circulation than the solid micarta bars.

Another example of starting with a less expensive material that still meets service requirements was in the production of distribution transformers. Originally, a porcelain plate was used to separate and hold the wire leads coming out of the transformers. A fuller board plate was substituted which stood up just as well in service, yet was considerably less expensive. The industrial engineer should keep in mind that such items as valves, relays, air cylinders, transformers, pipe fittings, bearings, couplings,  chains, hinges, hardware, motors, etc., can usually be purchased at less cost than they can be manufactured.

FINDING A MATERIAL EASIER TO PROCESS

One material is usually more readily processed than another. By referring to handbook data of the physical properties, it is usually easy to discern which material will react most favorably to the process that it must be subjected to in its transposition from raw material to finished product. For example, machinability varies inversely with hardness and hardness usually varies directly with strength. The  properties of materials can be presented in tables in various ways to  form the basis on which a material is chosen. The tabulation shows the relation between various materials and properties when one of the variables such as thickness, stiffness, strength or weight is held constant. By keeping the thought in mind of selecting a material that is easy to  process, one industrial engineer was able to show real savings when he changed the procedure of producing stainless steel bearing shells. Originally, they were made by drilling and boring to size cut lengths of stainless steel bar stock. By specifying stainless steel tubing as a material  material was conserved, rate of production was increased, and cost of manufacture was reduced.



USING MATERIAL MORE ECONOMICALLY

A fertile field for analysis is the possibility of using material more economically. If the ratio of scrap material to that actually going into the product is high, then consideration should be given to greater utilization.

For example, if a part required 18 inches of 2-inch × 14-gauge seamless steel tubing (including the width of the cut-off tool) and random lengths had been supplied, it would be well to specify to the source that this tubing should be delivered in exact multiple lengths of 18 inches. This procedure would prevent short ends being left over.

In the production of stampings from sheet, if the skeleton seems to contain an undue amount of scrap material, it may be possible to go to the next higher standard width of material and utilize a multiple die. If a multiple die is used, care should be exercised in the arrangement of the cuts to assure greatest utilization of material.

Another example of economical use of material is in compression molding of plastic parts. By pre-weighing the amount of material put into the mold, only the exact amount of material required to fill out the cavity will be used and excessive flash will be eliminated.

SALVAGE MATERIALS

The possibility of salvaging materials that would otherwise be sold as scrap should not be overlooked. Sometimes by-products resulting from the unworked portion or scrap section offer real possibilities for savings.

One manufacturer of stainless steel cooling cabinets had sections of stain- less steel 4 to 8 inches wide left as cuttings on the shear. An analysis brought out a by-product of electric light switch plate covers.

Another manufacturer, after salvaging the steel insert from defective bonded rubber wringer rolls, was able to utilize the cylindrical hollow rubber roll as bumpers for protecting motor and sail boats while moored.

If it is not possible to develop a by-product, then scrap materials should be segregated for top scrap prices. Separate bins should be provided in the shop for tool steel, steel, brass, copper, aluminum, and chip haulers and floor sweepers should be instructed to keep the scrap segregated. It is usually wise to salvage items such as electric light bulbs if large quantities are used. The brass socket should be stored in one area, and after breaking and disposing of the glass bulb, the tungsten filament should be removed and stored separately for greatest residual value. Wooden boxes from incoming shipments should be saved and the  boards sawed to standard lengths for use in making smaller boxes for outgoing shipments. This practice is always economical and is being followed by many large industries today as well as service maintenance centers.

Full use of supplies AND Tools

Full use of all shop supplies should be encouraged. One manufacturer of dairy equipment introduced the policy that no new welding rod was to be distributed to workers without return of old tips under two inches long. The cost of welding rods was reduced immediately by more than 15 per cent. It is usually economical to repair by brazing or welding expensive cutting tools such as broaches, special form tools, and milling cutters. If it has been company practice to discard tools of this nature, once broken, it would be well to investigate the potential savings brought about by a tool salvage program. The unworn portion of grinding wheels, emery discs, etc., should be checked for possible use in the plant. Such items as gloves, rags, etc., should not be discarded once they are soiled. It is less expensive to launder them to reuse than to replace them. Waste of material benefits no one. The industrial engineer  can make a real contribution to his company by preventing material wastes which today claim about one fifth of our material.

SUMMARY: In every manufacturer's shop, materials constitute a large percentage of the total costs of the products of production. Consequently, the proper selection and use of materials is important, not only from the standpoint of giving the customer a more satisfactory product, but also because by selecting a material which is more economical to process, production will be performed at a lower cost.

Process Industrial Engineering

PROCESS OF MANUFACTURE

As there are a great number of materials to select from when designing a part, so there are almost an unlimited number of manufacturing processes to choose from when planning for its production. New and improved methods are constantly being developed. A new process may be developed in one plant to satisfy a particular design or project. Investigation will often reveal several other places in the plant where it could be used to advantage over the existing process.

For example, to finish the outside diameter of a product, a setup on an infeed centerless grinder may have been developed. A survey may disclose that the centerless grinding can produce other products faster that were formerly turned down on a lathe, and still have a better machine finish. No methods analyst can ever expect to learn every process and be in- formed on the various operations of the equipment and its limitations as to tolerance, capacities, and various applications. However, by keeping the basic fundamentals in mind, he will be in a position to foresee opportunities for improved processes throughout his organization. For example, the requirements of clean surface, proper fusion temperature at joint, and pressure to force the metal together and hold it while cooling, are applicable to forge welding, butt welding, flash welding, spot welding, projection welding, seam welding, and percussion welding. If the methods analyst understands these fundamental requirements, he will be in a position not only to see possibilities for developing better joining techniques, but will be able to clear up troubles encountered in welding processes. It is wise for the industrial  engineers to review current technical periodicals to identify and accumulate ideas for use in his work of continuous improvement of products and processes. Possible application for improvements should be clipped and filed for future reference, and in time an invaluable manufacturing methods library can be developed.

Ideas for method improvement are often crystallized when you see “what the other fellow is doing.” They have to collected and maintained in a file indexed for each recall when needed. 

By systematically questioning and investigating manufacturing processes, new and better methods will be evolved. It is well for the industrial engineer to adopt the philosophy, “The current way may not be the best way to do a job—there can always be a better way and I have to search, think and decide.” From the standpoint of improving the processes of manufacture, investigation should be made in four ways:

1. When changing an operation, consider possible effects on other operations.
2. Mechanize manual operations.
3. Utilize more efficient facilities on mechanical operations.
 4. Operate mechanical facilities more efficiently.


EFFECTS ON SUBSEQUENT OPERATIONS BY CHANGING PRESENT OPERATION

Before changing any operation, it is wise to consider detrimental effects that may result on subsequent operations down the line. Care is required in analytically changing an element in an effectively running process. Taylor gave the caution to take all precautions to validate that quality is not affected due to productivity improvements. Industrial engineers who do analytical improvements have to consider all downstream effects of a change.   Reducing costs of one operation can result in higher costs on others. For example, a suggested change in manufacturing of A.C. field coils resulted in higher costs and was, therefore, not practical. The field coils were made of heavy copper bands which were formed and then insulated with mica tape. The mica tape was hand wrapped on the already coiled parts. It was thought advantageous to machine wrap the copper bands prior to coiling. This did not prove practical as the forming of the coils cracked the mica tape, and time-consuming repairs were necessitated prior to acceptance.

Rearranging operations often results in savings. The flange of a motor conduit box required four holes to be drilled—one in each corner. Also, the base had to be smooth and flat. Originally, the job was planned by first grinding the base, then drilling the four holes in a drill jig. The drilling operation threw up burrs which had to be removed in the next step. By rearranging operations so that the holes were drilled first, and the base then ground, it was possible to eliminate the deburring operation. The base grinding operation automatically removed the burrs.

By combining operations, costs can usually be reduced. Formerly, the fan motor supports and outlet box of electric fans were completely fabricated, painted separately, and then riveted together. By riveting the outlet box and fan motor support together prior to painting, and then painting the assembly, appreciable savings in time was effected on the painting operation.

MECHANIZE MANUAL OPERATION

Any time heavy manual work is encountered, consideration should be given to possible mechanization. To clean insulation and dried varnish from armature slots, one company resorted to tedious hand filing. By questioning this process of manufacture, an end mill placed in a power air drill was developed. This not only took most of the physical effort out of this job, but allowed a considerable higher rate of production. The utilization of power assembly tools, such as power nut and screw drivers, electric or air hammers, and mechanical feeders, often are more economical than hand-tool methods.

Utilize more efficient facilities on mechanical operations.

Can a more efficient method of machining be used? is a question that should be foremost in the analyst's mind. If the operation is done mechanically, there is always the possibility of a more efficient means of mechanization. Let us look at some examples. Turbine blade roots were machined by performing three separate milling operations. Cycle time was high, as well as costs. By means of external broaching, all three surfaces were finished at once. A pronounced saving was the result.

The possibility of utilizing press operation should never be overlooked. This process is one of the fastest for forming and sizing operations. A stamped bracket had four holes that were drilled after the bracket was formed. By designing a die to pierce the holes, the work was performed in a fraction of the drilling time.

Another applicable example of utilizing a more efficient machine was conversion of steam-heated ovens to banks of infrared lamps for drying transformer tanks after painting. The change allowed drying of the same volume of tanks in one twelfth the time.

OPERATE MECHANICAL FACILITIES MORE EFFICIENTLY

A good slogan for the industrial engineer to in process improvement is to try the idea, “Design for two at a time.” Usually, multiple die operation in press-work is more economical than single stage operation. Again, multiple cavities in die casting, molding, etc., should always be given consideration when there is sufficient volume.

On machine operations, the analyst should be sure that proper feeds and speeds are being used. He should investigate the grinding of cutting tools so that maximum performance will result. He should check to see if the cuttings tools are properly mounted, if the right lubricant is being used, and if the machine tool is in good condition and is being adequately maintained. Many machine tools are being operated at a fraction of their possible output. Always endeavoring to operate mechanical facilities more efficiently will pay dividends.

SUMMARY:

There are usually a number of ways to produce a part. Better production methods are continually being developed. By systematically questioning and investigating manufacturing processes, the analyst is bound to find a more efficient method. Always question the process of manufacture with an idea toward improvement. The current way may not be the  best way to do a job. In industrial engineering always investigate whether there is a better way.

Inspection and Quality Control

For inspection, in an instance, it was possible to introduce an automatic control on an external cylindrical grinder. Formerly, it was necessary to manually feed the grinding wheel to the required stop. Each piece had to be carefully inspected to assure maintenance of tolerance on the outside diameter. With the automatic machine control, the feed is tripped and the piece released upon completion of the in-feed. The automatic machine control made the operator free to do other work because some methods analyst endeavored to develop an ideal inspection procedure. In an automatic screw machine shop, it was thought necessary to inspect 100 per cent parts coming off the machine because of the critical tolerance requirements. However, it developed that adequate quality control would be maintained by inspecting every sixth piece. This sampling procedure allowed one inspector to service three machines rather than one machine.

Inspection procedure is also to be industrial engineered. Invariably, inspection is a verification of the quantity, the quality, the dimensions, and the performance. Inspection in all of these areas usually can be performed by numerous methods and techniques. One way is usually better, not only from the standpoint of quality control, but also from the time and cost consideration. The industrial engineer  should question the present way with thought toward improvement. The possibilities for installation of spot inspection, lot-by-lot inspection . or statistical quality control should be considered. Spot inspection is a periodic check to assure that established standards are being realized. For example, a nonprecision blanking and piercing operation setup on a punch press should have a spot inspection to assure maintenance of size and the absence of burrs. As the die begins to wear or deficiencies in the material being worked begin to show up, the spot inspection would catch the trouble in time to make the necessary changes without the generation of any scrap. Lot-by-lot inspection is a sampling procedure in which a sample is examined in order to determine the quality of the production run or lot. The size of the sample selected is dependent on the allowable per cent defective and the size of the production lot under check. Statistical quality control is an analytical tool which is employed to control the desired quality level of the process. If a 100 per cent inspection is being encountered, it is well to consider the possibility of spot inspection or lot-by-lot inspection. One hundred per cent inspection refers to the process of inspecting every unit of product and rejecting the defective ones. Experience has shown that this type of inspection does not assure a perfect product. The monotony of screening tends to create fatigue, and thus lowers operator attention. There is always a good chance that the inspector will pass some defective parts as well as reject good parts. Because a perfect product is not assured under 100 per cent inspection, acceptable quality may be realized from the considerably more economical methods of either lot-by-lot or spot inspection. Usually, any elaborate quality control procedure is not justified if the product does not require close tolerances, if its quality is easily checked, and if the generation of defective work is unlikely.

Just as there are several mechanical methods for checking a .500"/.502” reamed hole, so there are several over-all policy procedures that can be adopted as a means of a control. The methods analyst must be alert and well grounded in the various techniques, so that he can make sound recommendations for improvement. In one shop a certain automatic polishing operation was found to have a normal rejection quantity of 1 per cent. It would have been quite expensive to subject each lot of polished goods to 100 per cent inspection.

It was decided, at an appreciable saving, to consider 1 per cent the allowable per cent defective, even though this quantity of defective material would go through to plating and finishing only to be thrown out in the final inspection before shipment. The analyst must always be aware of the fact that the reputation and demand for his company's product depend upon the care taken in establishing correct specifications and in maintaining them. Once quality standards are established, no deviations will be permitted. In general, tolerances and specifications can be investigated in these three ways: 1. Are they absolutely correct? 2. Are ideal inspection methods and inspection procedures being used? 3. Are modern quality control techniques being exercised?


Equipment/Machine Work/Effort Analysis/Study/Improvement

Nadler had written equipment/machine change refer to changes in the equipment, machinery, tools, jigs, fixtures, work place etc.,

As an example of equipment change, Nadler discussed the proposal to spin one pin at a time on a arm. Industrial engineers suggested that these pins can be riveted and in one set up four rivets can be placed thus saving substantial time of the machine. In this case both operation and the equipment have changed.

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https://www.youtube.com/watch?v=b31oEBYu-T4


Further work to continue and develop the article.

Ud. 14.6.2023

Pub  16.11.2019