Knowledge-based selection and sequencing of hole-making operations for prismatic parts

This paper describes the rule structure used to select the appropriate sequence of operations to produce various types of holes in 21/2D prismatic components manufactured on machining centres. Operation selection is based on forward chained rules coded in Prolog. A different rule priority sequence is applicable depending on the rule fired last. This solves the conflict resolution problem and ensures reasonably fast execution. Rule conditions perform feature extraction, feature size checks, operation suitability checks, tool suitability checks and processing status checks. Actions perform the processing operations and update the model through feature processing tags. The knowledge base implemented for hole-making was not obtained from a practical industrial environment. Nevertheless it does produce sensible plans and it is relatively easy to modify.