All these works lead to new approaches integrating the complete cost and spread accounting methods based on the enterprise activities (ABC for instance). French economist, G.Perrin [2], since the Sixties, also developed a method based on one single cost-inductors through all the steps of the product development process (Added Value Unit method). We implemented such a costing management in a French sand casting foundry in order to allow a several-level management, based on indicators linked to the exact costs of the product to be delivered [3-4]. During this PHD thesis we validated the concepts but also the methodology required for a complete numerical traceability.