Inspection of curvic couplings using a CMM

Abstract

The inspection of curvic coupling geometry is usually done by using a mating master curvic to check the transfer of a very thin coating of engineering blue from the master to the curvic being inspected. The mating master curvic is also used to measure dimensions such as swash, radial runout and overall stacking height. Although the method is relatively quick, it needs a skilled eye to interpret the bluing patterns, and it does not produce any numerical data on the curvic form. The development of new methods for machining curvic couplings places a greater emphasis on having numerical data in order to provide inspection feedback. Rolls-Royce has investigated the use of a coordinate measuring machine (CMM) to inspect curvic couplings, and this paper discusses some of the problems and successes.