This work defines an expert machinability data system integrated with a CAD system, for computing complete machining parameters required for further processing with NC software. The main objective is to move toward the concept of a fully computerized system, from design to the generation of NC code which can be directly sent to a manufacturing unit. A typical example of such a system, MICADEX, is described in this thesis. MICADEX is capable of retrieving geometric description of components from their 2-D CADAM drawings using the IUE (CADAM Access) facilities and making decisions on machining parameters required for the turning operation, in consultation with the user. MICADEX is designed to be a representative example of an intelligent system capable of providing virtual machining facilities on a CAD system, and lt does not require its users to have a high level of engineering skills. / Master of Science