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Inspecting Bolts, Nuts and Screws pg 498 CONTINUED
And now for something completely, but not entirely different.
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Assembly operations in the aircraft industry are simplified by the use of three-dimensional drawings. Known as pro-duction illustrations, they include only necessary assembly information and present it clearly
Three-Dimensional Views Boost Plane Production
A MAJOR DIFFICULTY in training un-skilled workers for assembly-line oper-ations has been the reading of blue-prints. Advanced blueprint reading requires training, and practice. A new man without this skill, or with only an elementary knowledge, may spend hours in attempting to decipher an involved design. If he asks for help his foreman may understand the print himself, but lack the ability to convey this understanding to the worker by word pictures. A solution to this problem first in-troduced in 1939 has worked with such
MAY 28, 1942
success that it is now used in a number of aircraft plants and is under consid-eration by the Training Within Indus-try branch of the War Production Board. Blueprints are eliminated in assembly line operations, and their place is taken by isometric, or three-dimensional drawings, known as pro-duction illustrations. These sketches are broken down into essentials so that a given drawing de-picts only information needed for a given series of operations. Since the parts to be assembled are preformed, there is no necessity to clutter up the
drawing with dimensions and details. In their early stages, the drawings were used by the Douglas Aircraft Company as sales illustrations for vis-ualizing planes to prospective buyers. When the war brought extensive orders from England and France, mass pro-duction of Douglas military planes became a possibility, and the introduc-tion of thousands of untrained workers became a problem. Starting with a staff of four artistic-ally-inclined engineers, George Thar-ratt built up a production illustration department. They drew sketches of
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production-line proposals. Ideas for special equipment, new tools, and new methods of manufacture were passed from department to department in pic-ture rather than word-description form. It was found that a proposal need-ing approval could be explained ver-bally to an illustrator who would sketch and resketch it until the originator's ideas were accurately conveyed. An :idea presented in isometric-sketch form permitted the proper authority to pass . on its merits quickly and intelligently. If found to be suitable the idea was ready for the engineering department to plan construction in detail.
The next step was to apply the sketches to actual production, using them to explain in simple form the assembly operations to be performed. In one plant a test was made to deter-mine their value, and two crews, one with an illustrated sketch, and one without, were assigned to assemble left-and right-hand wing spars respectively. The crew working with the sketch com-pleted the first unit in 1.9 hours while the crew working without the sketch required 5.4 hours. Similar savings were found in the inspection depart-ment. Blueprint difficulties are greatly mag-
nified in electrical and plumbing in-stallations. To search through many engineering electrical prints to find needed installation data is a slow and laborious task. For such work, sketches which present only the necessary ma-terial are particularly valuable. By including jig and tool require-ments on the illustration, more time is saved. The line employee, whether new on the job, filling a working posi-tion that has been changed, or to which he has been temporarily assigned, does not have to experiment or interrupt the work of others in order to learn what tools to use.
These Assembly Drawings for a Bombardier's Door Illustrate the Technique
An enlightening comparison can be made by following through the assem-bly drawings for a bombardier's lower door and comparing the ease with which the sequence of operations is understood with the difficulty that -would be encountered in trying to pick the same information out of the blue-prints of the parts involved. Fig. 1 of this series depicts five as-sembly operations each joining two or more preformed parts. Each numbered arrow indicates one of these operations. In actual practice the sketch would have listed alongside the number and
name of each part required in each of the operations. The frame is riveted together in the manner shown in Fig. 2 of the se-ries. At first glance this may appear to be a complicated assembly to present to an inexperienced man with a single drawing, but each part can be clearly identified and the sequence of riveting the frame together is given by the cir-cled numbers. Assembly begins with the four rivets at (1) and continues through operation (31) . A note ex-plains that at stations (16) , (17) , (18) , and (19) only top and bottom
rivets are inserted. After operation (31) the middle flush rivets are in-serted. One rivet is omitted at sta-tions (24), (28), (9), (7), (20). The reason for these two variations becomes evident in the next drawing. In Fig. 3 six additional assembly operations are performed. When nec-essary, parts are drawn out of position and arrows used to indicate the method of placing them. Angle ribs are riv-eted into position where rivets were omitted or flush rivets used in the preceding sketch. In one operation the skin is riveted in place.
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AMERICAN MACHINIST
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FIG.2 Flush rivets at 16, 17, 18, 19 are inserted after operation 31
Code + Rivet omitted x Flush rivet
Fig. 4 (next page) shows the door inverted so that it rests on the skin side. In this position the emergency pull handle mechanism is installed. En-larged detail views of this mechanism are given at A and B. After installa-
Lion of this mechanism the top cover plate shown in view C is assembled and attached to the door to complete the assembly. Order of operations again is indicated by circled numbers. From this example it can be seen that
complex designs and blueprints which are bewildering to the uninitiated are translated into simple isometric draw-ings which contain only information relative to particular assembly opera-tions. (Continued on page 509)
FIG. 3 Use %8" rivets on ribs and fair-leads
—Use 3/52" rivets MAY 28, 1942
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1 Lok Skru Lok Skru and screw • R. H. rivet x flush rivet
View C
AC 366-F832
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7. Hardness tests are made on many bolts follow-ing heat treatment. The Rockwell tester shown at right is motorized. The minor load is applied by hand, the major load by power. If close hardness limits are specified the surface is first ground flat. The machine is checked twice daily against a master disk
8. Microscopic inspection of surface condition is required on some bolts and screws, especially for air-craft work. Bench inspection equipment is used, as illustrated at right center, but high magnification is not essential. Inspection is made to check bolts and screws for freedom from fine scratches
9. Completed parts are placed in tote pans on a gravity conveyor which delivers them to the final in-spection department. Each batch passes first to an inspector, far right, who checks a certain percentage of the parts. If defects exceed an allowable figure the entire batch goes to inspection benches
10. Slowly moving belts are used for sorting and inspecting nuts when specifications do not require more exacting tests. Commercial bolts and screws re-ceive similar rapid inspection. If those tested do not meet specifications then the entire batch receives de-tailed tests and defective parts are scrapped
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11. Aircraft bolts and screws are inspected on ordinary flat top benches, shown below, at which the girl inspectors sit. They take bolts from a pile in front of them and make a visual inspection for defects, especially in threads. Ten percent of a batch are checked with go and no-go gages ; if they do not pass inspection the entire batch is checked
AvogagiggraN,
And now, Inside Detroit, Red Tape, Building Invaders, The airplane, not Barbarians.
And now, Inside Detroit, MichiganInspecting Bolts, Nuts and Screws CONTINUED
INSIDE DETROIT
BY RUPERT LE GRAND
Tool Service To balance the sup-to Be Expanded ply of gages with de-mand, the Tooling Advisory Service of the Automotive Council for War production will be ex-panded to a national undertaking, ac-cording to plans now in the making. The program has the enthusiastic en-dorsement of General Campbell, chief of Ordnance, and of Generals Glancy and Armstrong of the Combat-Auto-motive Center. Each week the Tooling Advisory Service, 514 Boulevard Bldg., Detroit, mails a pamphlet "Available Tooling Facilities" to 1500 tool buyers. The Oct. 19 issue lists 115 tool shops in the Detroit area (and a few in other states) according to delivery time promised on jigs and fixtures, gages, cutting tools, sheet-metal dies and forging dies. The precision rating of each shop is also indicated.
Will List Shop Facilities
One of the main pro-posals in the plan now taking shape is to list each week the same kind of in-formation for all of the tool shops in the country which can make plug, ring, snap, thread, spline and other forms of gages, as well as gaging fixtures. Probably, a national listing will com-prise between 200 and 300 names, be-cause at least 50 percent of gage and tool capacity, outside of the major gage-production shops like Brown & Sharpe, Pratt & Whitney, and Shef-field, is concentrated in the Detroit area. Moreover, the mailing of Avail-able Tooling Facilities will be expanded to perhaps 5,000 tool and gage buyers throughout the country. The purpose of the expanded effort is of course to bring together quickly the shop able to make a gage or tool with reasonably quick delivery and the pur-chaser, either in industry or in Ord-nance, Navy or Air Corps procurement offices. Often a tool or gage that is classified as a standard can not be de-livered in less than a year by one of the big gage or tool companies, but when treated as a special and given to a small plant or jobbing shop, it is possible to get fast delivery. For ex-ample, 32 out of the 115 job shops listed for the Detroit area by the Tooling Advisory Service are currently able to make delivery upon plug gages in three to six weeks. In fact the delivery situa-tion in several gage categories has im-proved markedly in recent months.
OCTOBER 29, 1942
Gage Demand to Increase
Tooling Advisory Service to expand; will issue bulletins advising from whom and when gage deliveries are available. Auto men urge return to their Detroit pre-war materials scheduling practice.
Nevertheless, gage procurement is one of the most serious problems in all manufacturing areas, and the demand for gages will increase with expanded armament production and design changes. To overcome the delays incident to customer-buying habits, lack of knowledge concerning all sources, and the tendency of even distant subcontractors to rely upon Detroit for gages, top ranking officers are enthusiastic concerning the possi-bilities of the industry cooperation through the expanded AWCP plan. De-tails of the entire plan are to be pre-sented to all gage-section chiefs of Ordnance, Navy, and Air Force pro-curement districts. Ordnance personnel are hoping that the expanded activities of the Tooling. Advisory Service will go far toward bal-ancing gage supply with demand by making full use of existing facilities on a national scale. They argue that merely giving shops additional machin-ery is not the best way of handling the situation. Future releases of ma-chine tools to tool and gage plants may depend upon demonstrated need after the current proposal has been tried.
HUDSON TO BUILD "INVADERS" DETROIT—A powerful marine engine, known as the "Invader," and much larger than an automo-bile engine, is to be built by Hud-son Motor Car Co. to power inva-sion barges for the Navy. Although the difference in size and design of the marine engine poses manufacturing problems, the Detroit firm will produce the power plant almost entirely with converted automobile machinery. Parts manufacture is already un-derway. The new contract is the third major war-production proj-ect which Hudson has revealed in recent weeks.
Clearing House Other features of Is Suggested the plan are still be-ing mulled over. One suggested by the Automotive Council for War Production is that each tool user appoint a man to act as a clear-ing house of information relative to tool needs and tools on hand. A cen-tral information clearing house may
also be established. Too often one plant has great difficulty in getting say a half dozen drills of a certain size, and a concern in the next community has an over supply. In the search to find gages to meet pressing Ordnance needs, it was orig-inally suggested that idle inspection devices left over from automobile pro-duction might be reworked. The merits of an expanded salvaging activity in respect to gages will be given serious study by AWCP. Automotive observers understand that they did not win complete ac-ceptance by WPB for the industry-sponsored materials scheduling plan, and that instead some features of both this plan and the steel budget plan will be combined into a new program to re-place the obsolete Production Require-ments Plan, or PRP. Close control of critical materials will remain, but with some flexibility and a minimum of pa-per work.
Wish to Avoid Red Tape
What the automotive industry wanted in the new materials control plan is avoidance of red tape and poor planning that either fails to get the material into the plant at the required time, or in the required quan-tities. PRP failed dismally here, for many plants did not receive fourth-quarter allocations until well into the final 90-day period, and in many cases cut-backs on materials gave them un-balanced supplies of commodities. It is not much help to get 50 percent of copper, and 90 percent of alloy steel, for production is pulled down to the level of the lowest percentage, and in-ventories are built up for materials in the higher percentages.
Central Plan Is Like Peacetime
A committee of top ranking automobile men visited Wash-ington to explain the advantages of the materials-control plan, which in many aspects follows customary Detroit practice in peacetime. Vital features of the materials scheduling plan as it is called were: (1) bills of materials be submitted to Washington, (2) require-ments of all bills of materials to be totalled, (3) comparison made with the charts of materials available, (4) Army and Navy to fit orders to materials available. The holder of an order would then have the right to place materials orders with vendors, later reporting
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And now, Inside Detroit, Michigan, War Rulings in brief on Scrap ect, The Kiser Yard,
Liberty ship Building time steadily shortened.His purchases to WPB for auditing and checking. Thus, Washington's paper work, the bottleneck to date, would not interfere with actually putting the goods into production. The Iron and Steel Branch of WPB, and Ferdinand Eberstadt, a deputy chairman of WPB (and formerly an investment banker) favored the steel budget plan which required the manu-facturer to work out the materials re-quired for an order and then justify them at Washington, before getting a certificate. That, said Detroit, is just so much more red tape. If allowed to proceed on the usual lines or setting up materials bogies on a 90 day basis, and then releasing them on a 30-day schedule as in the automotive produc-tion days, actual arms output could be cut back at any time by dropping a few days production. There still seems to be some question at Washington, in re-gard to the trustworthiness of indus-trial leaders. To argue that Detroit
will grab all available materials, be-cause it knew where to bring pressure in pre-Pearl Harbor days, is to take a dangerous line. For as one automotive spokesman said, the issue of materials control is next in importance to mili-tary strategy toward winning the war.
WPB Shows How It's Done
WASHINGTON—Object lessons in the substitution of non-essential materials are presented by an exhibit prepared by WPB. Shown are a large number of substitutions of glass, cast and ma-chined steel for bronze, brass and cop-per, and displays of many uses of plas-tics. Included is sponge glass, which is impregnated with gas and weighs as much as balsa wood, and floats. Also shown is a glass sleeve, which fits over the machined stubb of a propeller blade while the blade is being sandblasted; glass sleeves outlast steel sleeves many times over.
WAR RULINGS IN BRIEF
Checklist of Significant Regulations on Materials and Prices
ALUMINUM SCRAP—If borings, turn-ings and similar machinings contain oil, water or other forms of contami-nation, maximum prices may be paid only on basis of actual weight of alumi-num or aluminum alloy contained. (Amend. 1, Revised Price Schedule 2.)
AUTOMOTIVE REPLACEMENT PARTS—Application of PRP has ren-dered ineffective Amendment 1 extend-ing terms of order until Dec. 13, 1942, and it has therefore been revoked. (P-107, Revocation.)
CONVEYING MACHINERY & POWER TRANSMISSION EQUIPMENT — Ex-tension of 30 days for filing produc-tion schedules has been granted, effec-tive Oct. 7. (Amendment 1, Limitation Order L-193.)
EXPORTS — All exports, including Lend-Lease shipments and unrated orders, as well as those assigned prefer-ence ratings by Board of Economic Warfare, have been freed from end-use and inventory restrictions in foreign countries. (Priorities Regulation 15.)
HACKSAW BLADES—Sale of low-alloy steel blades used in ordinary hand frames is permitted. (Amend-ment 1, Preference Order E-7.)
HAND SERVICE TOOLS—Sales and deliveries by manufacturers have been limited to purchase orders rated A-9 or higher. At the same time further limitations have been placed on types of alloy steel from which these tools may be manufactured. (Amendment
2, Preference Order E-6.)
LIGHTING FIXTURES—Manufacture or sale of blackout and dimout fixtures which do not conform to specifications of War, Navy Departments and Mari-time Commission has been prohibited. (Order L-168.)
MECHANICAL PENCILS—A clarify-ing amendment changes the order to read "Pencils, mechanical or auto-matic." (Conservation Order M-126.)
NICKEL—Use of this metal has been restricted to implements of war and other products certified by Army-Navy Munitions Board, except where spe-cifically authorized by director general for operations. (Amendment to Con-servation Order M-6-b.)
STEEL CASTINGS, MANGANESE—New maximum price regulation estab-lishing ceiling prices to levels prevail-ing between Oct. 1 and 15, 1941, applies not only to producers but to all per-sons dealing in this material. (Maxi-mum Price Regulation 235.)
STEEL SCRAP, ALLOY—Segregation of low-phosphorus and low-sulphur stainless steel turnings has become mandatory in order to prevent indis-criminate melting. (Amendment 1, Supplementary Order M-24-c.)
THERMOPLASTICS—Effective date of scheduling provision previously post-poned to Oct. 1 has been again post-poned to Nov. 1. (Amendment 3, Preference Order M-154.)
Liberty Ship Building Time Steadily Shortened
WASHINGTON—Liberty shipbuilding time continues downward to the amaze-ment of all observers and the conster-nation of the Axis. Admiral Emory S. Land, chairman of the Maritime Com-mission, promises that all transport operations will be returned to private ownership when peace comes. Mean-while, the Commission and the indus-try are both wondering what should be done with the Liberty ships when ocean commerce is reestablished. And all surface shipping men, eyeing the volumes of cargo being flown by the Air Force Transport Command, fear that airlines operating heavy equip-ment all over the world, will seriously cut into their traffic. Both the Italian and the German governments give the lie to reports of speed on our ship construction—to their citizens. But they well know the truth, and they are deeply disturbed, as well they might be. For in Sep-tember, Liberty ship time went down from 8.3 days in August to 70.1, aver-age in the ten yards participating. Kaiser Yard Again Leads The Kaiser yard, Oregon Shipbuild-ing Corp., at Portland, is again lead-ing at 42.0 days average for 11 ships in September. Kaiser still holds the single ship record, too: 13 days 231/2 hours. Second to Kaiser's average is the McCone-Bechtel California Ship-building Corp., at Wilmington with a record of 55.9 days in September for 12 ships. Kaiser's other two yards are fourth and sixth in the running. Number 10, slowest of all, is the Todd-Bath South Portland Shipbuilding Corp., South Portland, Maine, with an average of 198.0 days for one ship in September. But even the slowest is excellent, by comparison with the average time of 241.3 days last January. It is a fact, little-noticed, that the Maritime Com-mission originally estimated the Lib-erty ship could be built in 105 days, and the builders said it was not pos-sible. Admiral Land's promise to give ship-ping back to its original owners come peace is no surprise, of course. A mat-ter of real concern is what to do with the Liberty ships, which will constitute one-fifth of the world's tonnage if the war ends in a reasonable time. The chairman says these ships can be (1) sold to foreign countries, (2) sold to speculators, or (3) be held in reserve for emergency by the government. Apparently there is no thought that these ships can stay on the seas in competition with faster vessels which this country and others will build. Thus, except for our relatively small number of "C" ships, we will still face the need for a new merchant fleet if we are to resume our rightful place in world ocean traffic.
I 254h AMERICAN MACHINIST
