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Aviation History
1955
1955 - 0776.PDF
774 FLIGHT, 3 June 1955 SOLDERING ALUMINIUM A New Process Approved by the M.o.S. for Aircraft DETAILS of the development of what are claimed to be thefirst solders approved by the Ministry of Supply for joiningaluminium and aluminium alloys have recently been released by the Sheffield Smelting Co., Ltd., whose laboratorieshave evolved what is known as the Thesscal process. Research was directed towards attaining a satisfactory mediumbetween soft soldering at around 250 deg C and brazing at about 600 deg C. On light alloys, the former process usually results ina low-strength joint with poor corrosion resistance, while the latter involves temperatures too high for joining thin-gauge sheetof the strong age-hardenable materials such as Duralumin, and introduces risk of distortion. Extensive tests of the process were carried out by the R.A.E.prior to the granting of M.o.S. approval; humidity tests lasting nine months were made by the Radar Research Establishment,Malvern; and the Metropolitan Vickers Electrical Co., Ltd., Rolls- Royce, Ltd., various airframe manufacturers and the AluminiumDevelopment Association have also co-operated. Trials have in- cluded salt-spray tests of joints and two-year exposure to Sheffield'sindustrial atmosphere. A series of British and foreign patent applications has been made. The work resulted in the production of two hard solders,Thesscal "A2" and "P.12," which have been approved to speci- fications D.T.D. 900/4367 and D.T.D. 900/4398 respectively. "A" has a melting range of 420 deg C to 450 deg C and isused with the maker's No. 92 flux. Main application is on sheet metal and fabricated forms of aluminium and its alloys. Thisis a free-running solder, and the technique of use is very similar to that of silver soldering, "P.12" hard solder has a wider meltingrange, namely, 440 deg C to 510 deg C. Not so free-running as Thesscal "A," it can be moulded rather in the manner ofplumbers' solder. Its use is principally in aluminium alloy cast- ings—to repair broken castings, build up lugs and protrusions,join castings to sheet metal, and to fill in blowholes or incorrectly positioned drill holes. Like the other, it is used with No. 92 flux. Thesscal "A" is stated to have particular application for air-craft equipment, and for unstressed or lightly stressed parts, in situations where the low process-temperature enables thin Duralu-min sheet or sections to be joined by unskilled labour without danger of fusion. One manufacturer has used the process forassembling elevator tips from light-gauge Alclad, thus effecting a weight-saving in comparison with the welded assembly in heavier-gauge material previously used. Weight-saving, it is pointed out, can also be effected by re- CANADIAN HUNTING APPOINTMENTS SOME recent appointments in three Hunting Group companiesin Canada have been announced. Mr. Fred M. Hanna has joined Hunting Associates, Ltd., as technical assistant to Mr. D. N.Kendall, vice-president. He will assist Mr. Kendall in the estab- lishment of technical policy in all companies in the group. Mr.Hanna's previous appointment was as chief engineer of P.S.C. Applied Research, Ltd., one of the Hunting Associates companies.He is closely associated with this company's development of air- borne magnetometers and radiation detectors. Mr. George Suarez has been appointed general manager ofField Aviation Co., Ltd., Oshawa, Ontario. Formerly manager of the survey-flying division of the Photographic Survey Corpora-tion and Renting Aviation, Ltd., Mr. Suarez has been with P.S.C. since 1947. One of Canada's most experienced helicopter pilots, Mr. AlSoutar has become manager of Renting Aviation, Ltd. He has been closely connected with the group's aircraft operations since hejoined the Photographic Survey Corporation, the first Hunting company in Canada, on its formation in May, 1946. STORING DRAWINGS "PROM Randalrak, Ltd., 106 Victoria Street, London, S.W.I,-*- come details of a storage system for engineering and other drawings—in fact, any such document that can be rolled—thatappears to combine the advantages of maximum space-economy and minimum time-expenditure in locating a particular drawing.These "Planstore" units consist of a number of compartments each housing a rectangular plastic socket, one end of which isclosed by two inclined surfaces terminating in a lug handle. Both surfaces incorporate a reference-label holder and the angle ofpresentation permits easy reading at any height. A drawing is A Duralumin-to-aluminium test joint in 76 s.w.g. sheet. After hammer- ing, the aluminium has cracked but the joint-line is unaffected. design of assemblies in the light of the fact that Thesscal will not only join a wide range of aluminium alloys one to another, but will unite any of them to copper, brass, phosphor-bronze, Tungum, gunmetal, nickel, nickel silver, steel, and stainless steel. Application is a straightforward matter of heating with a braz-ing torch. Two considerations, however, have to be taken into account. The first is that, as in many silver-soldering processes,the flux is corrosive and must be washed off the joint. The Thess- cal flux, however, has the advantage of being quickly soluble inhot water. The second consideration is that Thesscal-soldered joints cannot be anodised, because they are attacked chemicallyby the solution; but this difficulty can be overcome by using pro- prietary stop-off lacquers before anodising. Where some formof protection of the whole assembly is called for by specification, etching primers and paints can be used quite successfully; thisalternative method is approved by the M.o.S. Thesscal "A" solder, in the "as cast" condition, is stated tohave the following properties: yield point, 8.4 tons/sq in; U.T.S., 9.4 tons/sq in; elongation, 5 per cent; electrical conductivity,22.3 per cent I.A.C.S. Detailed technical data, including results of destruction and other tests on joints, are obtainable from theSheffield Smelting Co., Ltd., Royds Mill Street, Sheffield 4. rolled and one end inserted into the socket, which grips thedocument flexibly yet firmly. The other end is then introduced into the compartment and the socket pushed fully home, thussuspending the drawing horizontally in the body of the unit. Drawings can be removed and replaced without disturbingOthers and can be quickly located in the unit by a simple system of reference: when one is removed a "location slip" may be sub-stituted and the socket replaced with its handle in the vertical position, thereby indicating "drawing in use", and the locationslip at once identifies the user. Planstore units are available in three heights, 89in, 46in, and34in. The unit fronts are divided into approximately 1,200, 600 and 300 compartments. All units are 37in wide but vary in depthaccording to the size of drawings to be stored. - INSTRUMENTS ON SHOW AN exhibition of precision electronic equipment and com-L ponents made by a number of American and Continental firms was held recently in London. Organized by Rocke Inter-national, Ltd., and B. and K. Laboratories, Ltd., the exhibition included equipment for research, production and maintenance.Among the items on view were a sound frequency-analyser and level-recorder made by Bruel e Kjaer of Denmark; varioussignal generators, oscilloscopes and other test equipment of American design; a temperature-measuring bridge and an audio-meter from the Dutch Peekel company; and data recorders from a range suitable for laboratory work on vibration, aerodynamics,gas turbine performance and other aeronautical applications (Ampex Electric Corporation, U.S.A.). The Rocke company, whose address is 59 Union Street,London, S.E.I, are British representatives for a large number of American and Continental manufacturers of such electricaland electronic instruments, components and equipment.
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