In the early phases of the product life cycle, cost controls became a major decision tool in the competitiveness of companies due to world competition. After defining the problems related to these 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 approach) and some specifics limitations of the tool used for this development. Finally we will discuss the limits of a generic approach.