Reliability Analysis Of The Feed System Of The Heavy CNC Machine

Feed system is one of the key subsystems of heavy CNC machine. It not only achieves the multiple directions of machine tool feeding, but also plays a vital role on machining accuracy of CNC machine tools. The event of failure will not only reduce the efficiency and affect the work processes, the safety of operating personnel will be endangered as well. Thus, the reliability analysis and research tools are the keys to the development process of machine tools. Failure Mode, Effects and Criticality Analysis (FMECA) is known as an effective mean to ensure the reliability analysis of the possibility of failure and potential failure modes. It could be used to determine the relative fault severity, the faults probability and judge if a significant impact would be occurred when component failure. While improvement measures have been proposed, the potential flaws and weaknesses can be reduced or eliminated by redesigning, manufacturing, processing technology, et al. Thus the reliability of the whole machine will be improved.In this paper, the major research aspects which aim at the reliability of feed system of CNC machine tool are organized as follow:(1) The feed system of CNC machine FMECA is based on the structure and function of the feed system. We give the system construct and establish the reliability model. By reliability analysis, potential failure modes and fault cause can be set out by using Bayesian method. Compensations and improvement measures are proposed for each failure mode. High hazard degree parts and failure modes are highlight in this paper.(2) On the basis of reliability analysis, reliability suggestion method is put forward for the feed system of heavy CNC machine tool which makes customer and manufacturer to work in understanding of the importance of reliability.(3) On the basis of FMECA join FTA auxiliary analysis, a fault analysis process is present to analyze the probability of Top Event. Both of quality and quantity are considered in this paper so that the parts with high probability importance can be found.In the design, research and development period, FMECA and FTA can be used to mitigate the degree of harmfulness and the failure frequency. While a reliability workflow has been given to clarify the customers’ and manufacturer’s responsibilities, it is envisioned for NC machine tool to improve its work efficiency and provides guarantee of the reliability of machine.