Neutral Definition and Recognition of Assembly Features for Legacy Systems Reverse Engineering

Current CAD systems provide utilities to position and orient parts with respect to each other in assemblies through associative relations that include geometric and parametric constraints. However, assembly features are not explicitly defined, nor available in CAD databases for exploitation in downstream applications. This paper examines the attributes of assembly features and proposes a template for their definition in a uniform way. The template can be used in conjunction with an EXPRESS-like language (N-Rep) to define assembly features that are implementation independent. The template includes slots for part features, mating relations, geometric, parametric, kinematic and structural relations. The current application for assembly features being explored is for Reverse Engineering of legacy parts. Assembly features serve as “knowledge containers” in that they allow one to encode form, fit and function in a uniform way so that replacement parts can be redesigned to meet key requirements.