Saturday, July 7, 2012

Manufacture - 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.
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.

14. Each casing is manufactured from the lightest material commensurate with the stress and tempera- tures to which it is subjected in service. For example, magnesium alloy, composites and materials of sandwich construction are used for air intake casings, fan casings and low pressure compressor casings, since these are the coolest parts of the engine. Alloy si eels are used for the turbine and nozzle casings where the temperatures are high and because these casings usually incorporate the engine rear mounting features. For casings subjected to intermediate temperatures i.e. by-pass duct and combustion outer casings, aluminium alloys and titanium alloys are used.

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