3.1 The Cost Entity concept and the modelling logic
The aim of our study is to sharply manage the costs (direct and indirect) during the production of sand casting parts. As illustrated previously, it is imperative to give a tool to the engineers of the engineering and design department in order to help them to control the costs of the parts design. In collaboration with the company Cognition Europe, and on the basis of the tool Cost Advantage, we work on the costs models to apply in the case of the steel sands casting parts. We are based on a preceding work, proposing an integrated approach for the sand foundry, realized within the framework of a thesis in partnership with SMC Colombier Fontaine (France) of group AFE Metal [2]. This work allowed formalizing the base of knowledge trade necessary to the control of the product life cycle in a foundry company. In addition, we validated an approach, a methodology and a deployment leading to ensure an exact knowledge of the parts costs and their impact on the output of the company [4].
Let us start with the concept of cost entity and context, which are our modelling bases.
3.1.1 Costs Entities
A Cost Entity is a grouping of costs associated with the resources consumed by an activity. The general condition is due to the homogeneity of the resources, which makes it possible to associate a single inductor: the entity cost [5]. The model allows expertise formalisation, knowledge capitalisation and to have, at the early design phase, some information about the production step. Moreover, it helps the communication between all collaborators during the product life cycle.