Process planning knowledge representation using an object-oriented data model

The issues involved in forming proper knowledge representation for process planning are discussed. Following a brief review of knowledge representation schemes used in existing reported CAPP systems, the profess planning function and its required knowledge are described. Then an object-oriented knowledge representation scheme is presented that allows both upstream and downstream integration of CAPP and makes it easily adaptable for interfacing with other computer integrated manufacturing (CIM) modules. Descriptions of machining process entities and their relationships with features, machines and cools are provided. The network representation of the process plan that allows for alternative plans is explained. The application of the scheme within a working process planning system prototype is briefly explained and supported with an example. The benefits of the proposed representation, which include connection with geometric model, reduced search space, and alternative plan generation, are discussed. These new contributions provide for a new generation of CAPP systems that can be easily adapted for various manufacturing systems and can be integrated with other CIM modules.