The High-efficiency On-line Abnormality Diagnosis and Control Methods for Micro Milling

The machining abnormalities, such as milling chatter and cutter breakage, can severely deteriorate the machining quality and machining efficiency of a micro milling process. A system which can early detect and activate necessary control for the occurrence of micro milling chatter and micro cutter breakage is necessary. In this study, with use of Fast Fourier Transform and the algorithm of short-time signal variation analysis the methods of on-line diagnosis and instant control of milling chatter and cutter breakage were developed. With the control commands generated by the proposed monitoring system and the designed direct communication module, micro-milling chatter can be fast suppressed (within 2-3 sec) to minimize the possible damage caused by the chatter, and the machine can be instantly stopped (within 1 sec after cutter breakage occurs) for cutter replacement. In the diagnosis/control process, actual machining information was on-line extracted from the PC-based controller for abnormality diagnosis. The experimental results have shown the good feasibility and effectiveness of the proposed methods.