Fault diagnosis of machine tools

Abstract

The efficiency of manufacturing systems depends to a high degree on the reliability and availability of metal-cutting machine tools. Therefore, the detection and diagnosis of incipient and abrupt faults is of high importance. Statistics with regard to failure causes show for computer-numerical-control (CNC) drilling machines that tool faults constitute 27%, CNC faults 16%, mechanical faults 5%, electrical faults 4% and others, like organizational faults 34% and lack of orders 14%, [9.10], [9.40]. Hence, tool wear, breakage and collision contribute considerably to machine tool failures. Failure statistics for turning machine tools and machinery centers around 1993 showed that CNC and electrical failures constitute about 8%, and failures in the mechanical parts, like tool carriers 25%, workpiece handling 16%. These numbers underline the importance of automatic supervision or condition monitoring of machine tools. It is not only the breakdown of the manufacturing process that counts, but also damaged workpieces and tools.