An Object-Oriented Modeling Approach for Production Scheduling on CNC-Machines in Flexible Manufacturing System to Maximize Cutting Tool Utilization

Abstract

This paper discusses production scheduling problems on CNC-machines having a set of cutting tools in a Flexible Manufacturing System (FMS) to maximize the cutting tools utilization. This objective has been selected because it is frequently found that cutting tools are under-utilized as they are used far below their respective lifetime limits. We will consider the situation where several identical CNC-machines are operated in an FMS; each of which is equipped with the same cutting tool configuration. The jobs to be scheduled are machining parts, and each of the parts requires one to two stages of processes, and each of the stages consists of several sequential operations, where a specific operation requires a certain type of cutting tool. Whenever a certain cutting tool is being used, the time consumption will be accumulated to calculate its remaining lifetime. The assignment of an operation to a particular CNC-machine will be based on the sufficiency of the cutting tool remaining lifetime to complete the operation. We formulate the problem in a mathematical model and then solve it using a solution method based on the object-oriented modeling approach, where the FMS elements are grouped as classes of the objects, i.e. the CNC-machine, the cutting-tool, the product (job) and the storage classes. Numerical examples show that the proposed solution method can effectively solve the scheduling problem.