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Aviation History
1958
1958 - 0486.PDF
502 FLIGHT, 11 April 1953 THE INDUSTRY Plates for Integral Machining DURING the past few weeks over half a million pounds' worthof new production equipment has been put into service at the Rogerstone, Monmouthshire, works of Northern Aluminium Co.,Ltd. The major part has been installed to meet the needs of the aircraft industry, specifically for high-strength aluminium-alloyplate in the large dimensions necessary for integrally machined skins; and large plates, but in medium-strength alloys, are alsobeing produced for the shipbuilding industry. Noral aircraft plate is produced initially by first hot-rolling castor pre-forged ingots. The resultant billet is then heat-treated in a large new bottom-loading furnace with a quenching-tankbeneath. Built by Stordy Engineering, Ltd., to Northern Aluminium specification, the furnace is of the electrically-heated,air-circulating type, with a total heater rating of almost 1,500 kW. The furnace and quenching-tank—the latter with a useful capacityof 60ft long by 6ft wide by 15ft deep—are fully mechanized in operation and together permit complete solution treatment andartificial ageing, with annealing if necessary. The quenching process inevitably sets up internal stresses inplate of the dimensions here produced, stresses which could lead to serious distortion during machining of the plate by the aircraftconstructor. After the quench, therefore, the plates are subjected to a controlled stretching operation to give a minimum of 1| percent permanent elongation. This operation is performed by a machine which—as we sawduring a recent visit to Rogerstone—is probably the most impres- sive of all the new pieces of equipment in the works. Designedand built by the Loewy Engineering Co., Ltd., it has a rated pull of no less than 4,000 tons, and can apply a controlled stretch tolight-alloy plates (up to 50ft long, 10ft wide and 6in thick) with a maximum cross-sectional area of 200 sq in. The jaws which gripthe plate at each end are operated by 400-ton hydraulic rams, while the two main stretcher rams—which, with 7,000 lb/sq inhydraulic pressure, can exert a maximum pull of 6,000 tons—are each of 36^ diameter. An elaborate shock-absorbing system isincorporated to prevent damage to the machine in the event of a plate tearing. Keeping them Clean AIRCRAFT cleaning preparations are a speciality of Valay- Industries, Ltd., of 186 Campden Hill Road, London, W.8, and their "Jove" range now consists of four principal products. K2 Wadpol (to D.T.D. 900/443,8) is an impregnated waddingfor quickly removing corrosion and weathering effects from sur- faces, either polished or painted, without damage; Aerowash addi-tive is a compound which, added to wash-down water, speedily removes grease and grime; Aerowax is a lightweight high-glosswax finish, for high-speed aircraft, applied by cloth or spray and giving a durable weather-protective finish (it may also be usedas a preservative for stored parts); ani Aeroval is a non-inflam- mable cleaner for cabin interiors, designed to remove dirt and stainsfrom a wide variety of materials, including leather, leathercloth, plastics and carpeting. Wadpol is supplied in 7-gal cans and theother three products in 1-gal cans, four cans to a carton in each instance. Among users of these products are the Royal Air Force (includ-ing the Queen's Flight) and Commonwealth Air Forces, the U.S.A.F., B.O.A.C. and a number of other major airlines, andleading aircraft manufacturers. Northern Aluminium's new plate-stretcher. Two other major items of equipment complete the plate-production plant. One is a saw for trimming the stretched plate to size. Made by Wadkin, Ltd., it is powered by a 75 h.p. motor,and the tungsten-tipped circular saw (itself fed forward by a 6\ h.p. motor) can slice through a six-inch-thick plate of Noral26S, a high-strength aircraft alloy, at 90in/min. Spanning the saw-table is a 68ft beam weighing 20 tons and carrying 18 pairsof hydraulic jacks which press the plate firmly to the table. The final piece of equipment is an ultrasonic flaw-detectioninstallation by Curtiss-Wright of America. Operating on the immersion principle—the plate is laid in a tank of water 54ft long,14ft wide and 3ft deep—it depends on the use of probe units which, mounted on a two-directional travelling carriage, scan thewhole area of the plate, directing into it the ultrasonic wave to give echoes that are reproduced visually on oscilloscopes. Two oscillo-scopes, operating in plan and elevation of the workpiece, show the operator the exact location and size of any internal flaw. In view of the potential consequences of an undetected flaw inmaterial for skin-machining—expensive scrapping at the produc- tion stage, or the possibility of something even more serious whenthe aircraft goes into service—the need for meticulous testing of this kind scarcely needs emphasis. A detailed description of the new equipment and processes willbe found in the May issue of our sister-journal Aircraft Production. Abrasion-resistant Nickel TN London on March 31, Metachemical Processes of Crawley,•*- Sussex, introduced micrograin nickel, a new type of material which, although extremely hard, is very flexible. This material, of0.00001-2in grain size, represents a striking advance in the science of electrical deposition. It can be controlled to be extremely hard(up to Brinell 600) and it does not appear to work-harden under repeated reverse bend tests, although only limited investigationhas yet been carried out. The deposition coating, which is depen- dent for its grain size upon the grain size of the base metal, has sofar been made in a nickel-electroform with the metal deposited electrically in a standard nickel sulphate bath on to a resin base,after a flash coating of copper has been deposited. This coating, several millimetres thick, is electrically conductive. The first application of the process has been the production ofvery strong protective sheaths for propeller de-icing elements. A master mandrel of metal is prepared by casting from thecontours of the propeller, the conductive plastic coating is applied and then the nickel is deposited electrically. A heavier thickness(about 0.025in) at the leading edge is formed naturally. The process can be worked with other metals. Fire-extinguisher Hose A NEW fireprbof flexible metallic hose, designed to meetA.R.B. and C.A.A. requirements for piping in aircraft fire- extinguishing systems, is announced by Power Auxiliaries, Ltd.,of Swindon, Wilts. Shown in the accompanying photograph is one of the tests to which the new hose and its union fittings wassubjected during the development period. Fixed in a vibrating- rig, the assembly was subjected for 15 min to a temperature of2,200 deg F generated by three gas flames directed on the union. A 12-lb Graviner extinguisher was then discharged through thehose. It is stated that it remained undamaged by the thermal shock of the cold fluid and was found to be completely fit for service at1,000 lb/sq in. Testing Power Auxiliaries' fire-extinguisher hose under vibration and heat (see news-item above).
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