Good Tooling Simplifies Production of Flying Fortresses

By Boyd K Bucey,
Superintendent of Tooling, Boeing Aircraft Co

Correct tooling methods not only speed production of parts but frequently reduce assembly time and make possible employment of more unskilled labor.

With more than 100,000 specially designed tools built and currently in production, and probably an equal number of standard tools which required no design, the Boeing Aircraft Co's tooling department is in high gear for the production of the Boeing Flying Fortress, one of the many tools of victory. This 200,000 figure is exclusive of the commercially produced tools, such as lathes, pneumatic riveting hammers, electric drills, and the like, which are listed at Boeing as plant equipment. Including these, the tools used to produce the Flying Fortress would total more than 250,000. These implements of production have been turned out since the declaration by the President of the state of national emergency. But the tooling organization at Boeing which made this record has not always been in existence.

Growth of the tooling department at Boeing has paralleled the increase in Flying Fortress production. Quantity production of any product cannot be achieved without the tools necessary for increased output.

In former days, before the ugly thereat of war reared its head in Europe, the Army Air Corps considered 40 Flying Fortresses in a year to be a substantial order. Extensive tooling played a role in the production of such orders, the tooling activities being devoted to the building of drop hammer dies, the designing and building of jigs and fixtures, which in most instances seldom exceeded one or two of each kind. Templates were made to check accuracy, and other devices which aided production were built.

Prior to 1930, at the Boeing Aircraft Co's plants in Washington, tools were planned in the shops and built by the men who built the planes. In those days, when the all-metal plane was just being introduced, if a new or different rivet bucking bar were required, a man got a piece of scrap metal and ground one out to the desired shape. Special tools, as they were required, were developed by a group reporting directly to the factory superintendent. In those days, the Boeing plant, while one of the largest in the nation, employed less than 3,000 persons. With most of the personnel being highly skilled workers, and by and large familiar with the problems involved throughout the construction of the small orders of planes which aircraft companies managed to obtain, extensive tooling was not economically practical. At present, the tooling department alone almost equals the total Boeing payroll of more than a decade ago.

About 1930, one man in the department began to design tools which aided in the production of the Boeing 247. This ship, the forerunner of the modern air transport, marked on innovation in aircraft construction. Boeing's order for the ship was quite substantial and because no commercially produced tools were available, special tools had to be built for the job. Wing spar drill jigs, riveting mice, standard tools such as angle drills, punch and die blanks, and the like, were designed for the more rapid production of the transport ship that brought airline travel into the three-mile-a-minute class.

In those days, the tool records consisted mainly of a rubber serial number stamp and a stenographer's notebook in which the item was recorded, as well as where it could be found in the plant. Machining fixtures, drop hammer dies, and the like, were made in the shops by skilled workers, direct from engineering prints, and without the necessity of tool design. Complete interchangeability of parts was not as great a prerequisite of production in those days. Tool planning at Boeing was then under the production office, and was not a separate department. Design of special machines, jigs, tools, etc, was handled, as formerly, with the equipment engineers.

Boeing-designed planes, over a period of years, brought about a complete change in the trend of aircraft, from the tri-motor to the bi-motor 247, from the Army B-9 to the Boeing 299, the original Flying Fortress. Subsequent development of four-engine commercial planes, such as the Stratoliner, the Clipper, and the many models of the Flying Fortress led to Boeing's establishment of a tooling department called Engineers of Manufacturing, a fairly complete unit which planned tools, designed tools, and followed through in the manufacturing shops to see exactly what tools were most urgently required to expedite production. Just prior to this time a tool fabrication shop was organized, separate from the machine shop, and manned by skilled machinists and tool and die makers. A jig shop, comprising primarily welding experts, was divorced from the production welding shops to work exclusively on the building of jigs for the production of four engine planes.

During 1940 the present tooling department, an expansion of the Engineers of Manufacturing, was formed to handle tooling in all its phases: Design, engineering, and fabrication. Vastly increased orders for the Flying Fortress and previous plant expansion in separated areas called for more design of tools and more detailed planning of tools which were needed for production. Problems which formerly could be solved by personal contact could no longer be handled. Instead of hammer dies of the past, double and triple action deep draw dies came into use in the fabrication section, using huge mechanical and hydraulic presses.

Jigs were built in batteries. New and present, a deep draw die makes one part which is spot welded to the skin highly specialized machines, designed and built by Boeing, took their places along the production lines. Special pieces of handling equipment were devised to expedite the moving of large heavy parts of assemblies. Through extensive tooling, Boeing got into quantity production of the Boeing Flying Fortress, the ship which no less authority than Gen Arnold has called "the guts and backbone of our worldwide aerial offensive."

Frequently, in the process of manufacturing an article, the determination of the amount to be spent on tooling is based on the following factors making up the cost of the finished part: Cost of the tool, plus the cost of the labor which uses the tool, plus the amount of material wasted, totaled, then divided by the number of parts which are required to manufacture the finished product. Boeing has gone even further. It has been determined that this fabrication cost frequently used in computing the cost of the part represents only 20 percent of the total labor cost of producing the plane. The remaining 80 percent is the time required to assemble the parts into the finished aircraft. Consequently, anything which tooling can do to shorten the amount of assembly time required for each Flying Fortress results in speedier production at a lower labor cost per ship. If the tooling cost seems higher than the part itself might justify, but the assembly time is reduced, the tool is scheduled into production.

One typical example of this is the method of making the doors to the ship. Former practice was to rivet about 40 pieces together making the door. At of the door, which comprises the entire part. Many small jigs, and the time required to put together and rivet the 40-odd pieces has been eliminated.

In these days of manpower shortages, devices which expedite production are of paramount importance, not only in the saving of time for labor but in reversing the adage of "too little and too late."

Exact saving which Boeing tooling has effected in production cannot be accurately determined. But at the Flying Fortress factory the number of man-hours required to complete one of the four-engine bombers has been reduced considerably. It is generally conceded that the lion's share of this reduction can be credited to better production methods which have resulted from the extensive tooling program.

For example, metal clips are attached, in numerous places, to the circumferentials of the Boeing Flying Fortress. The clips are used to attach lining, small assemblies, installations, etc. Method of locating these clips is through coordinated holes. For quantity production, special piercing dies are developed to locate the holes in the proper place on the circumferentials. In earlier days, during one rush production run, one of the punches broke. The production shop, instead of removing the die for repairs, completed the parts in order, and set up a Perkins punch to locate the missing hole, thinking this the fastest solution to the problem. By referring to the engineering print, the production shop determined that 1/32 in was as fine a tolerance as need be maintained. The tooling tolerance on these holes is plus or minus .0015, and the hole size 3/32. When these reworked parts reached the production jigs, one hole wouldn't match. The number of man-hours required to hand drill the unmatched hole, and complete the job was excessive and even more serious, upset the sequence of assembly operations, thereby delaying production considerably.

Incorrectly manufactured parts can result in abnormally high assembly costs which are difficult to segregate. If a part doesn't fit, the amount of rework on the job which must be done by the assembly shops is almost incalculable, and is never charged against the tool but always to assembly time. While routers and hammer dies can be set up faster, and put into production speedily, the parts are not completely accurate. A little too much pressure on the part of the router operator will cause the drill to lead slightly to one side. If the lag bolts on the router stock are not tightened, the stock may shift during routing, making the blanks of inaccurate size. Seldom can two parts even approach interchangeability, if made on hammer dies. There is a surprising amount of rework required to make these parts fit with ones which are produced by more accurate tools to closer tolerances.

Nevertheless, these methods which were used for the past several years by the aircraft industry still have a place in the manufacturing of military types of aircraft. There is no method quite so rapid for the development of parts required to incorporate a design change dictated by tactical operations. Boeing uses these tools to incorporate, with a minimum amount of time, changes requested by the air services in the Boeing Flying Fortress. Meanwhile, however, better tools are beginning to manufacture these parts with considerably more accuracy — blanking dies, draw dies, or the like.

Tool coordination, planning, and scheduling have an important function in the operation of the tooling department here. It is not at all unusual that 500 tools be required to produce one large, complex part. An engine mount would be a typical example. Having all of the tools finished and ready for production when the part must be made is no small task. This is accomplished by a systematic record which is brought up to date daily, and in some instances, oftener. Load schedules are maintained on every machine, and each shop in the tool fabrication section. By keeping tool fabrication within the tooling department, there is no buck passing. Everyone works toward the common goal of getting out the tools, and making certain that the tools will turn out the parts. It would be difficult to single out any of the tools as outstanding.

One of the many Boeing developed machines which captured the nation's imagination was the "Octopus," a weird looking hydropunch which notches the circumferentials of the Flying Fortress for more rapid joining of the longitudinal stiffeners. This machine can operate up to 19 dies at one time on a radius of 190 deg. The dies are mounted in tracks which will accommodate the diminishing radii of the circumferentials/ The outstanding achievement of this machine lies in the fact that it can turn out work 45 times faster than the machine which it replaced. The basic idea behind the machines has proved so successful that Boeing will use adaptations of it for similar machines which are now under construction.

Probably no other machine, from a standpoint of time saving is as important as the Boeing developed automatic spot welder. This is a large table which permits the production department to weld together several panels of aluminum into one side of a wing skin. Moving ½ in in a small fraction of a second, the welding points make contact for .8 of a second, and the machine moves another ½ in. Indexing plates are provided to adjust the spacing between the rows of welds which are made on this machine. At the present time six of these welding machines are in use in our plant in Washington, there are others in other Boeing plants, while other aircraft manufacturers have adopted this machine for their welding needs.

The tooling job at Boeing has become a task of simplifying production of the Flying Fortress so that the army of inexperienced manpower can put together a complex fighting aircraft that will maintain the excellent reputation which has been built up over a period of years by the Boeing Flying Fortress. Output of Boeing Flying Fortresses at present is four times that of the time of Pearl Harbor. By providing working tools, the Boeing tooling department is aiding in speeding up the output of the fighting tools of victory.

This article was originally published in the January, 1943 issue of Aviation magazine, vol 42, no 1, pp 107-111, 221.
The PDF of this article [ PDF, 21.7 MiB ] includes a flow chart of tooling development at Boeing, nine captioned photos showing various jigs and specialized tools in use, and four detail drawings of parts of fixtures.
Images are not credited, but certainly come from Boeing.