Identification of cutting errors in precision hard turning process

During past 10 years, the availability of polycrystalline cubic boron nitride (PCBN) tools has made application of hard turning increase remarkably in a range of industrial areas, especially in automotive, roller bearing and hydraulic industry. Among the applications of CBN cutting tools, precision hard turning attracts great interests since its environmentally friendly and flexibility, which ultimately has potential to replace grinding. Using today’s high precision hard turning with high precision motion control, high static and dynamic stiffness and thermal stability CNC machine, the dimensional accuracy can reach IT5. However, this accuracy still does not meet the demands from most industries. In addition, precision hard turning has been hampered by uncertainties with respect to part quality and process reliability. Many factors affect the machining accuracy and process stability. The presented work analysis the possible error driver factor and error sources in a precision hard turning and the strategy of on-line compensation of the dimensional errors in the process, based on the monitoring of tool wear and prediction of thermal expansion. Test results indicate that within the certain range of flank wear the developed method can improve the geometric accuracy significantly.