Tool Status Recording and Its Use in Probabilistic Optimization

In batch production, recording the status of cutting tools and making decisions based on current tool status are important issues. In flexible manufacturing systems, there are normally many tools installed on machining centers. These tools are often used on different operations due to frequent change over in the system. The tool usage recording and the decision making based on tool status in this environment are crucial. The commonly adopted time measure is not sufficient because tool life is influenced by many factors. A tool status measure (tool wear index) is introduced in this paper. The index is affected by both direct cutting time and the type of cutting involved. Tooling cost recovery and probabilistic models are also developed to identify the cutting speed and replacement time based on tool wear index for minimum unit cost. The objective is to minimize the unit direct machining cost due to tooling, machining time, and in-process tool failure penalty.