The independent demand must be foreseen by the commercial area and can be considered in the process as the end item. Dependent demand the dependent demand in turn, directly is related with the demand of another item or existing product in the supply. This demand can be calculated and must be determined by the demand of the other item of which it is function. Optimum example of an item of dependent demand is the list of materials for the manufacture of one specifies end item. The adoption of a MRP system presents diverse benefits, including: lesser Nveis of supply; Melhor attendance to the customer (Level of service); Otimizao of the productive resources. The MRP can be seen, in according to place, as a system of control of supplies of item of dependent demand. In this direction, it is an proactive system, data that the maintenance of the supplies prevents.

The products for the production are bought in the measure where they are requested. In the systems of control of supply of independent demand, the actions are taken on the basis of a date (spare System Periodic) or in a remaining amount (System of Continuous revision) that in these cases, they need permanent maintenance in the supplies (Corra and Gianesi, 2001). The MRP uses the data of the Program Master of Production (Master Production Schedule – MPS), of orders for originated components external, forecasts for the item of independent demand, registers of supplies, structure of the product or list of materials of the product, rude necessities and liquid necessities (Slack, 1997). Parametrizao of system MRP Corra and Gianesi (2001) affirms that the Parametrizao is the form of if adapting the calculation of MRP to the specific necessities of the organization. As the necessities and characteristics of the organization they are always moving, is also necessary to revise the parametrizao periodically. Definio of the Lead teamses: Time required for the system of production to execute definitive task; Definio of the sizes of lots of production: Optimized lots to suppress the demand; Definio of the lots of purchase: Ideal amount of purchase not to increase the raw material supplies; Estoque of Security: Level of supply necessary to guarantee production during one determined time.