In the early phases of the product life cycle, the costs controls became a major decision tool in the competitiveness of the companies due to the world competition. After defining the problems related to this control difficulties, we will present an approach using a concept of cost entity related to the design and realization activities of the product. We will try to apply this approach to the fields of the sand casting foundry. This work will highlight the enterprise modelling difficulties (limits of a global cost modelling) and some specifics limitations of the tool used for this development. Finally we will discuss on the limits of a generic approach.