The PPMP must quarterly be revised and be brought up to date. The planning of the short-term production (PPCP) determines what it will be produced in next the 4 weeks. This period varies of organization for organization in function of the flexibility of the productive process, being able to vary of 3 days up to 6 weeks. The evaluation of the raw material availability and the management of the efficiency of the productive process are the functions most important (Slack, 1997). With the defined planejamentos of short term, the programming of Production uses of methodologies and Tools to effectively elaborate the administrative orders for the operation. Amongst them we have the MRP (Planning of the Necessities of Materials), MRP II, MPS (Plan Master of Production), S& OP and ERP (informatizado system of management). MRP? Planning of the necessity of materials In the bibliographical reference of Moreira (1993), MRP (Materials Requirement Planning) is one technique to convert the forecast of demand of an item into a programming of the necessities of the contracting parties of the item. It determines how much it must be acquired of each item and where it dates these materials must be available.
Corra and Gianesi (2001) say on the subject, defining that MRP calculates is it of the required material necessities for the manufacture of determined product, by means of requests of the Plan Master of Production. Placing the resources in moment certain in the certain amount. The two authors follow the same line of reasoning when affirming that the MRP if constitutes as the ideal tool for the good management of the manufacture or rendering of services. The MRP is based on the definition of types of demand, independent and dependent. According to Moreira: Independent demand a demand is independent when it does not have relation with the demand of other item, therefore when it is not a function of the demand of any of the other item of supply.