This paper describes a general design model that serves as a base for computer-support in the conceptual design stage. The model consists of a model of the artefact to be designed, design activities and knowledge. The artefact model contains multiple views, each highlighting a certain aspect of the design. Design activities are performed to create this model and knowledge describes information generated in the past that can be reused. The general design model has been used to develop a specific model for the design of production machines. This specific model has been implemented in a prototype computer-program and has been evaluated within several companies. The results are promising and show that designers gain new insights by using the model.