A major difficulty in the development of advanced and integrated CAD and CAPP systems lies in the difficulty of representing components. Here some of the problems that are often encountered arc discussed and a composite component is used to demonstrate them. Possible approaches for solving some problems are proposed. The conclusion is reached that neither simple feature oriented design nor feature recognition methods alone will fulfil the requirements of advanced systems. Satisfactory modelling of the interactions between features in a component is a prerequisite to progress.

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The drive to integrate process planning with design systems to achieve concurrent engineering places new demands on the knowledge used in automated process selection. This paper highlights the current fragmented and unstructured nature of cutting process capability representation. Advances made in developing complementary models needed to analyse spatial process constraints are described in the context of an industrial case study and a simultaneous engineering workstation (SEW). The SEW uses a library of volumetric removal features to describe the shape-producing capabilities of processes. Attempting to model and plan sample parts on site showed up some problems in mapping from features used in design to the manufacturing processes, identified implicit interactions between features that needed to be recognized and showed a need for more detailed process error modeling. To overcome these limitations, geometric reasoning algorithms and complementary tool and machine models have been developed.

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