There are several motivations for linking together design-evaluation a
pplications and CAD systems - the avoidance of tedious and error-prone
reentry of data is just one. The paper examines the motives for linki
ng a widely used design-for-assembly (DFA) evaluation methodology with
CAD. The DFA methodology is described, and the interrogations of prod
uct data that it requires are explored. The extensions to an existing
solid-modelling system that are necessary to support these interrogati
ons are considered, with particular reference to the representation of
assemblies and assembly processes. An outline is given of how the com
ponent properties used by DFA are computed, and the role of geometric
reasoning in this.