A machining jig optimized for high-precision machining of turbine blades, which are principal parts in aviation gas turbine engines, was developed. The objective was methods of manufacturing that are high-precision, low-cost, environmentally considerate, and capable of application to mass production.Turbine blades are airfoil parts with three-dimensional geometry, and they are the most important parts in determining the performance of high-speed engines. They are manufactured by precision casting because they employ large amounts of heat-resistant alloys that are difficult-to-machine materials. The blade attachment part has a special shape and requires high precision, and is therefore finished by precision machining. It used to be that low-melting-point alloys would be poured into a fixture jig, using the airfoil surface geometry as a reference, and the piece would then be machined. However, fixing the blade in place and removing it involved a high-temperature dissolution process, and the labor required for the manual steps made this method unsuitable for mass production.An alternative material was sought in the recyclable, low-cost resins used in motor vehicles. The resin jigs were in a compact form machined to standards that would allow multiple blocks to be placed on the machining equipment; the material could be formed simply using the insert molding manufacturing process; it possesses the rigidity to allow high-precision machining; removal of the jig after machining would not result in blade deformation; and the resin should be recyclable. Based on experimentation, PPA was selected as the material and adopted for the fixture jig.
Article of Honda R&D Technical Review Vol.23 No.1 (36 - 43)