Actually, companies seek to continuous improve the management of their processes. Good manufacturing practices, improvement tools, and reliable information systems, among others, must support these processes in order to simplify tasks within the organization. One of the most important processes that companies have is the production planning. Within the planning there is a determining factor, that is the correct inventories management of both raw material and final products. Companies increasingly seek to work under a Make to Order production system, based on a raw material inventory that allows them to satisfy the customer requirements, but at the same time allows them to manage and reduce their costs.