Abstract: A CAD model of a component is designed by means of a CAD system that modifies the shape of the design of the component represented by the CAD model by means of templates held in a database of templates. The templates include machining data concerning the machining actions necessary to effect the alteration, represented by the template, of the shape of a work-piece. The CAD system outputs a computer model of the component comprising not only part geometry data concerning the shape of the component but also machining geometry data concerning the machining actions necessary for manufacturing from a work-piece a component having a shape in accordance with the outputted model of the component. This outputted computer model is then converted into an NC (numeric control) program by means of an NC program conversion module, by extracting NC code sequences from a database, the NC code sequences extracted corresponding to the templates of the UDF library used to design the shape of the CAD model.