Abstract
The lubrication performance of polyisobutylene which is used as a lubricant for screw tightening was studied in order to understand the lubrication mechanism during the tightening process. Ball on plate type spinning friction tests were conducted, and three kind of polyisobutylene(PIB-L, M, H) in which the highest viscosity is PIB-H, followed by PIB-M and PIB-L, and polyphenyl ether(5P4E) were used as lubricants in this study. Results at 400 MPa show that the friction coefficient tested in PIB depends on the viscosity, and the coefficient in PIB-H is the highest in the lubricants. It is also shown in results at 600MPa that the friction coefficient in PIB-L, H, 5P4E changes in the range from 0.2 to 0.5 during the test, and the contact area after the test shows large wear. On the other hand, the friction coefficient in PIB-M is lower than that in PIB-L, H, and wear amount in PIB-M is the smallest. These results suggest that the lubrication film formed by PIB-M has an ability to prevent for the direct contact between the surfaces at the condition with high contact pressure.
