New policy to manage tools in flexible manufacturing systems using network part programs

The high investment related to the acquisition of Flexible Manufacturing Systems forces firms to a better utilization of the machines. Different actions can be taken in order to avoid idle times of the machines: reduction of the unproductive times (time dedicated to rapid movements, tool exchange, pallet exchange, etc.), improvement of machines and, not last, a better management of the resources. The paper proposes a new policy for the management of tool operations in parallel machine FMS to minimize the idle times due to the lack of tools. The proposed policy uses new opportunities in manufacturing technology related with the use of network part programs in NC machines. It is already known in literature the potentiality of network part programs, more flexible than traditional sequential part programs that execute simply the rigid list of operations. Network part programs allow the different alternative ways to process each part. The way in which network part programs are executed by machines depends on the state of the tools and availability of the tools. The proposed method has been compared with other existing ones based on a real test case, a parallel machine FMS with two machines and a too carrier.