| Friction between micro components is different from macroscopic mechanical friction and nano-friction. Its value is from tens nN to a few mN. And it is the key factor that affects the performance and reliability of micro components such as MEMS (micro electro mechanical system) because of scale effect and surface effect. The friction in micro-mechanical systems is neither macro friction nor nano one. Hence, it is urgent to design an appropriate instrument to measure the friction in actual micro-mechanical systems. A new testing system was made to measure the micro-friction, which consists of four basic units:the feed system, rotational system, sensing system and data processing system. The three-dimensional structure modeling is designed by using CATIA software. Sensing system and data processing system are designed based on the light reflection method. The calibration experiments are carried out to verify linearity, repeatability and recovery of cantilever. From the result of experiments, the resolution of the normal load obtained can reach150μN, while the resolution of the friction can reach10μN. At last, experiments for micro-friction are carried out by using the testing system. The results of the experiment test showed that the coefficient of micro-friction is unstable:its value is changed with the normal load value. Self oscillating phenomenon and rebound phenomenon appeared in the process of the experiments. |
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