Discussion on shear properties and flow model in screw tightening lubricant PIB under low sliding speed conditions

This paper describes that shear properties and flow model in screw tightening lubricant PIB under low sliding conditions was investigated in order to understand the detail of lubrication condition on screw tightening surfaces. In this study, the sliding speed simulated in practical cases using M8 – M12 bolts were applied. The test results indicated that in the full-starvation condition, the film thickness that greater than the surface roughness of specimens was measured even in low speed cases, and the shear stress in the film was constant in all the conditions. It was also demonstrated from observation results by high speed camera that the PIB film moved to the sliding direction at the sliding speed, and that the film profile was almost same throughout the test duration. These results suggest that the PIB film transitioned to solidified film on the contact area, and that the wall-slip flow model was applied to the present conditions. Furthermore, the behaviors of friction coefficient and preventing wear obtained in this study almost corresponded to the results in our previous tightening test.