Capacities adjustment in the context of contract-order

Summary form only given. Nowadays, companies working in "contract-order" commit themselves with their suppliers by a global program of orders. Those companies promise to deliver within one year, at precise moment of the week, a product in varying quantities. They commit themselves to manage the flexibility of their capacity so as to guarantee their services and to optimize the costs. This guarantee of service requires ineluctably a flexible capacity in order to allow supplier to fit punctually his order-dealer\´s demand. In other words, the production system must be able to adjust its capacity to the requirement. This can be done by using different flexibility actuators. Classical models of planning operate in two different ways. The first one consists in carrying out, in medium term, production planning in a finite capacity way. So the load is adjusted to the capacity by smoothing the load during the time. The second one consists in carrying out, in medium term, production planning in an infinite capacity way. Two new approaches of planning are developed in this context tending to satisfy needs and to offer flexible capacity, in an optimal way. On the first hand, those approaches are based on the resolution of nonlinear mathematical programs. On the second hand, they are based on the use of different flexibility actuators (the overtime, the temporary workers, the subcontractors, the change of work\´s mode and an appropriate planning of loads). The integration of new flexibility levels in the planning process allows enterprise: to obtain the capacity and the load adjustment, to anticipate decisions and offers enterprise the possibility to evaluate its costs and its needs so as to better prepare their implementation.