Constraint-based design of parts

The key issues in design for machining are abstraction, classification, representation and checking of machining constraints. The paper proposes an object-oriented classification scheme for machining constraints. Design by machining features that are restricted by machining constraints are considered. The constraints considered in the paper are probably not original; however, their application at an early design stage to achieve a manufacturable design is novel. To date, these known constraints have not been transformed into a meaningful design paradigm. Thus, a mechanism for checking machining constraints at the early stage of design is presented on the basis of a part topology. Algorithms are developed to check related machining constraints for different cases of part topology. Therefore, for each feature, only a limited number of machining constraints need to be checked. The constraint classification scheme and a mechanism for checking constraints have been implemented as a prototype system, CBD, which is coded in c++ on an HP workstation.