In order to tackle a continuous improvement of virtual engineering, product modelling has to integrate always more knowledge that refer to every decision taken during the product development process. Those decisions have to be related to the assessment of the whole product lifecycle. This paper particularly addresses the domain of product's industrialisation that aims at selecting the manufacturing processes. This selection must currently be done as soon as possible and has to be strongly linked with product definition and CAD1 modelling. This paper presents first some new results concerning a product-process interface to integrate manufacturing information in the product model and how it leads the definition of the CAD model. Secondly this interface, that also manages specific information coming from the manufacturing process (tolerances, stresses gradient...), is used to improve the whole manufacturing process plan simulation. This process plan has, indeed, to track every material transformation issued from each manufacturing operation.