Cost control in the early phase of the product life cycle became a major competitiveness asset for the companies, due to the world competition. After defining the problems related to these control difficulties, an approach using a concept of cost entity related to the activities of the product to be designed and realized is presented. This approach is applied to the fields of the sand casting foundry. The enterprise modelling difficulties, limits of a global cost modelling and some specifics limitations of the tool used for this development, as well as the limits of a generic approach will be highlighted.