On the viability of developing CAD data exchange standard for form features

Form feature data exchange is divided into three types: CAD-to-CAD, CAD-to-Downstream applications and inter-downstream applications. Essential characteristics for CAD-to-CAD and CAD-to-Downstream types of feature data transfer are established flowed by a set of criteria for evaluation of a form feature exchange schema. Contemporary neutral feature data exchange schemas like AP 224, AP 203 and NRep are evaluated. It is concluded that none of them is fully equipped to do the job. AP 203 belongs to the CAD-to-CAD feature data exchange class. It exchanges only the final part geometry and the feature model is lost. AP 224 and NRep belong to the CAD-to-Downstream class. AP 224 attempts to enlist all features that can be manufactured using milling and turning processes. It limits the user to finite set of features. On the other hand, NRep permits the user to define his own features and does not provide a standard set. For a complete feature data transfer between two CAD applications, one needs to model the design intent of each design feature and transfer it with construction history of creation of the part model while for an efficient feature data transfer between CAD and downstream applications, the schema needs to standardize a set of most common features but also provide means for the user to define customized features with desired parameterization and attributes.