Variant process planning of castings using AHP-based nearest neighbour algorithm for case retrieval

This paper presents our research work on developing a computer-aided casting process-planning system using case-based reasoning. The nearest neighbour algorithm has been used for retrieval of a previous case ( solution) that is closest to the current case ( problem) under consideration. The algorithm is driven by product attributes related to geometry ( size, shape complexity, section thickness, etc.), quality (surface finish, tolerance, maximum void size) and production ( order quantity, production rate, lead time). Shape complexity, which plays an important role in process planning, has been quantified based on geometric parameters of the casting model. Weights to attributes have been determined using analytic hierarchy process (AHP), which allows pair-wise comparison and consistency checking of judgments. The complete methodology has been implemented in a web-based framework to enable early manufacturability assessment of castings through cost estimation and process simulation, both of which require process planning information. An industrial example is presented to illustrate the methodology.