2. The functioning of this type of engine, with its component lives comparable with rig test achieve-
high power-to-weight ratio, demands the highest ments.
possible performance from each component.
4. Engine components are produced from a variety
3．任何制造技術和工藝過程只要它能以任何形式提供某種優點就不會被忽略，最有用的工程方法和工藝過程都用于這些發動機的生產。在某些情況下，按某些標準來看，技術和工藝過程可能顯得復雜、贊時間而且花費大，但是，只有在證實它確實產生了與部件試驗臺試驗成果類似的最大部件壽命后才被采用。
Consistent with this requirement, each component must be manufactured at the lowest possible weight of high tensile steel and high temperature nickel and and cost and also provide mechanical integrity cobalt alloy forgings. A proportion of components are through a long service life. Consequently, the cast using the investment casting process. Whilst methods used during manufacture are diverse and fabrications, which form an increasing content, are are usually determined by the duties each produced from materials such as stainless steel, component has to fulfil. titanium and nickel alloys using modern joining
4．發動機的一些部件是用多種高強度鋼和高溫和鈷合金鍛件制成的。一部分部件是采甩熔模鑄造工藝過程的鑄件。同時，占比例越來越大的制造是采用不銹鋼、鈦和鎳合金這類材料用現代接合技術即鎢惰性氣體保護焊接、接觸焊、電子束焊和真空中的高溫釬焊制成的。
Manufacture
techniques i.e., tungsten inert gas welding, resistance welding, electron beam welding and high temperature brazing in vacuum furnaces.
5.
The methods of machining engine components include grinding, turning, drilling, boring and broaching whenever possible, with the more difficult materials and configurations being machined by electro-discharge, electro-chemical, laser hole drilling and chemical size reduction.
6.
Structural components i.e., cold spoiler, location rings and by-pass ducts, benefit by considerable weight saving when using composite materials.
7.
In addition to the many manufacturing methods, chemical and thermal processes are used on part finished and finished components. These include heat treatment, electro-plating, chromate sealing, chemical treatments, anodizing to prevent corrosion, chemical and mechanical cleaning, wet and dry abrasive blasting, polishing, plasma spraying, elec-trolytic etching and polishing to reveal metallurgical defects. Also a variety of barrelling techniques for removal o! burrs and surface improvement. Most processes are concerned with surface changes,
some give resistance to corrosion whilst others can be used to release unwanted stress.
8. The main structure of an aero gas turbine engine is formed by a number of circular casings, ref. fig. 22-1, which are assembled and secured together by flanged joints and couplings located with dowels and tenons. These engines use curvic and hurth couplings to enable accurate concentricity of mating assemblies which in turn assist an airline operator when maintenance is required.
MANUFACTURING STRATEGY
9.
Manufacturing is changing and will continue to change to meet the increasing demands of aeroengine components for fuel efficiency, cost and weight reductions and being able to process the materials required to meet these demands.
10.
With the advent of micro-processors and extending the use of the computer, full automation of components considered for in house manufacture are implemented in line with supply groups manufac-turing strategy, all other components being resourced within the world-wide supplier network.
Manufacture
11.
This automation is already applied in the manufacture of cast turbine blades with the seven cell and computer numerical controlled (C.N.C.) grinding centres, laser hardfacing and film cooling hole drilling by electro-discharge machining (E.D.M.). Families of turbine and compressor discs are produced in flexible manufacturing cells, employing automated guided vehicles delivering palletized components from computerized storage to C.N.C. machining cells that all use batch of one techniques. The smaller blades, with very thin airfoil sections, are produced by integrated broaching and 360 degree electrochemical machining (E.C.M.) while inspection and processing are being automated using the computer.
12.
Tolerances between design and manufacturing are much closer when the design specification is matched by the manufacturing proven capability.
13.
Computer Aided Design (C.A.D.) and Computer Aided Manufacture (CAM.) provides an equivalent link when engine components designed by C.A.D. can be used for the preparation of manufacturing drawings, programmes for numerically controlled machines, tool layouts, tool designs, operation
sequence, estimating and scheduling. Computer simulation allows potential cell and flow line manufacture to be proven before physical machine purchase and operation, thus preventing equipment not fulfilling their intended purpose.
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