No abstract

A typically occurring task when maintaining gas turbines is the replacement of broken or worn out turbine blades. In order to shorten costly downtimes, it is essential to provide spare parts with minimal lead time; this can turn out problematic in particular for older devices for which blueprints or type designations are not readily available. To overcome this limitation, reverse engineering (RE) methods can provide a remedy, since a geometrical representation of the piece can be obtained at short notice. Due to advances in additive manufacturing (AM) based production, it is also possible to print complex shapes with little additional effort. We present a framework that uses reverse engineering based on Computed Tomography (CT) and optical scanning to obtain the geometry of an AM-printed turbine blade test part and produces a duplicate thereof via the same fabrication technique. To verify the feasibility of the applied RE and manufacturing methods in practice, aberration of both procedures were investigated separately. Combining the results allowed us to review the replicated spare part for geometrical conformance with both, the original turbine blade and the initial design for the part. For this purpose we rely on a simplified approach based on standard deviation and shift of the mean value of error distributions that are obtained by comparing two known geometries to one another. We found that our workflow is capable of deriving the original part’s shape with adequate accuracy and offers the capability for obtaining a good baseline geometry that can be used for further treatment. The framework used is also able to provide meaningful information concerning manufacturing and imaging quality and quantify occurring aberrations of the workpiece. The replica itself exhibits acceptable geometrical deviations for actual productive service when compared to the initial design as well as the original part.