Optimal tool magazine operation. Part 2: rotating magazines with buffered tool change

Abstract

The paper examines the minimisation of the tool change waiting time of numerically controlled machine tools equipped with rotating tool magazines and buffering tool changers. The tool order in the various magazine operation concepts is optimised with the primary objective of minimising waiting time caused by tool change and magazine rotation. Other issues such as the total tool magazine travel are also considered. Numerical experiments are conducted and an industrial case is analysed. It was found that the optimisation is most beneficial if the magazine is large, cutting times short and the tool usage frequency distribution non-uniform. Waiting time savings of 50%–70% are typical compared to the case of random tool order in the magazine. A considerable reduction of idle times and magazine travels was reached in the industrial application described. The corresponding problem in the case of unbuffered tool change was studied in the earlier Part 1 of the paper.