ACCELERATED WEAR TESTING USING THE GRIT SIZE EFFECT

This paper describes a technique for wear prediction. It has been empirically established that the wear rate of an abraded workpiece is directly related to the grit size of the abrasive. Using this relationship, the wear rate of material subjected to very mild abrasion can be predicted from the measured wear rates of the same material under more severe conditions. This technique has been successfully applied to estimate the wear of magnetic recording head materials in a video tape system. Our results demonstrate that the wear rate of the head can be accelerated by as much as four orders of magnitude using abrasive lapping tapes of large grit size. The results also indicate that the wear rate of the recording head material decreases significantly with the magnetic or abrasive tape wear, which typically occurs during the first five to ten tape passes. Microscopic examination using scanning electron microscopy indicates that this reduction in wear rate is not due to clogging of the abrasive tape but rather to changes in abrasive particle shape. This means a recording head subjected to continuous sliding with fresh tape will wear considerably faster than a head which slides repeatedly against a loop of tape. Accordingly, in reporting the wear rates of head materials, it is important to describe the corresponding tape condition or usage history explicitly.