Inductive-deductive process design for machined parts

Abstract

In the design of the process to machine discrete mechanical parts, the sequence of removing material is arrived at to ensure that the resulting part is of the correct geometry and finish, and the process is safe, feasible and accomplished in minimum time. For complex parts, an experienced machinist makes use of inductive methods to relate similar part material, geometries together with interdependencies and their associated machining sequences which have produced quality parts in the past with minimum time expended, or deductive methods to generate a sequence by relating feature attributes (relative size and position) and relations (intersections and common tooling). Of interest is the interaction between the two methods because their coupling enables a self-improving design system to be realized. A feature-based solid modelling software environment provides the elements of a symbolic language for describing a discrete mechanical part in terms of its product and process design. The language is based on the use of features which the designer and/or machinist uses to associate and reason about the part and interaction between the machine, tool, fixture and starting raw stock for the various process design options involving the milling and drilling sequence for removing material. The machinist can either recall from experience, past designs contained in an associative memory, and/or activate generalized rules or constraints in a deductive memory to provide a feasible `good` design. As additional non-geometric features (tolerance, surface finish and material properties) are provided both feature and operation sequencing are refined.