Research On Technology Of Reliability Enhancement Testing For The CNC System

The reliability of CNC system is the key issue restricting our CNC system industry and the development of CNC machine industry. Due to the working environment and the quality of parts as well as the level of technology and other factors, there is a certain gap between domestic CNC system and famous brands. In this dissertation, a numerical control system of a CNC machine was taken as research object, the reliability enhancement testing technology was studied, and the accelerated failure mechanism was explored, so the theoretical basis to improve the reliability of the CNC system was effectively provided.The failure was statistical analyzed on the basis of the collected failure data of CNC system and the key subsystem was analyzed from the failure mode and effects and criticality (FMECA).The weak link to reliability was found. The key components and factors which affect the reliability of the CNC system were nominated.Based on the statistical analyzed of the failure data, reliability accelerated testing for fixed time at 208 hours were carried out. The most critical failure parts were found to be the numerical control panels and boards. The stress sensitive to affecting the reliability mostly was identified. Through the testing and analysis of the key components of the motherboard and the power monitor, the changing law of speeding failure about the motherboard and the power monitor were found. The external factors and internal factors affecting their failure modes were identified.The reliability enhancement testing technology of the CNC system was studied based on the results of the accelerated reliability testing. The typical testing profile of reliability enhancement testing for the CNC system was designed. The reliability enhancement testing for one-day was done by using HALT / HASS reliability test system of QUALMARK company, including temperature cycling test and the whole axis random vibration test. The validity of the technique was verified. A strong basis for the reliability improvements was provided. The reference for further applications of reliability enhancement testing was also provided.Finally, the failure mechanisms of the key devices for chip and power supply of the CNC system were analyzed from their internal structure and working principle. The potential failure causes of the chip and power in the designing, manufacturing and field service were analyzed. Some suggestions to improve product design reliability were made in terms of the analyses of failure mechanisms.