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．任何制造技术和工艺过程只要它能以任何形式提供某种优点就不会被忽略，最有用的工程方法和工艺过程都用于这些发动机的生产。在某些情况下，按某些标准来看，技术和工艺过程可能显得复杂、赞时间而且花费大，但是，只有在证实它确实产生了与部件试验台试验成果类似的最大部件寿命后才被采用。
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．发动机的一些部件是用多种高强度钢和高温和钴合金锻件制成的。一部分部件是采甩熔模铸造工艺过程的铸件。同时，占比例越来越大的制造是采用不锈钢、钛和镍合金这类材料用现代接合技术即钨惰性气体保护焊接、接触焊、电子束焊和真空中的高温钎焊制成的。
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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