An evaluation of surface asperity profile changes in truncation processes using optical interferometric microscope

摘要

The truncation process as running-in wear was applied to evaluate surface asperity changes as removal at the top of its asperity profile. The measurement was done using an optical interferometric microscope. Whole surface profile was measured by the microscope supported by the stitching technique. The specimen was relocated on the microscope utilizing Hirth coupling as a hardware technique. Data obtained from a truncated specimen were precisely relocated to the original untruncated specimen by computer software in three dimensions. Then the profile change was obtained by deducting truncated data from the original data. The profile change was calculated as removed volume. The volume changes are plotted against a sliding length. As the software relocation technique needs the unchanged profile of a valley part, the evaluation is limited to where the truncation height is higher than - 1.28 sigma (the standard deviation of untruncated original profile height). The present research can detect very little volume change that cannot be measured by other conventional methods, such as the gravimetric method. The advantages of the present method are as follows. It is possible to compare the truncated surface profile with the original untruncated surface profile in three dimensions. Thus, the inclination of the truncation surface can be evaluated and any other local changes can also be assessed. From this information the profiles of truncated surfaces will be linked to functions, and new parameters for truncation profile will be presented.