Automatic production of NC code for machining form features in generic parts

A prototype system for CAPP (computer-aided process planning) and the automatic generation of NC code for machining form features in generic parts is described. By means of this system, it is possible to program and simulate all the operations involved in the production of a part. The planning of the production process starts with the solid model of the final part, the solid model of the blank, as well as models of the available machine tools. It is assumed that the part has been modelled using a design-by-feature approach. This has two advantages: it makes the design easier, and features are automatically tagged for recognition at the process planning stage. Features are available in an archive and are stored in parametric form. After having specified the setup of the raw or semi-machined part, the machinable features are selected. A number of possible machining processes are associated with each feature. Machining processes are stored in a knowledge base organised as a network. The most suitable process is selected, on the basis of available knowledge, or directly by the user. The system then determines the list of required tools, their optimal sequencing, and the transfer and working paths for each tool. Machining commands for tool operations are then generated