ACCELERATED WEAR TESTING USING THE GRIT SIZE EFFECT

This paper describes a technique for wear prediction. It has been empi rically established that the wear rate of an abraded workpiece is dire ctly related to the grit size of the abrasive. Using this relationship , the wear rate of material subjected to very mild abrasion can be pre dicted from the measured wear rates of the same material under more se vere conditions. This technique has been successfully applied to estim ate the wear of magnetic recording head materials in a video tape syst em. Our results demonstrate that the wear rate of the head can be acce lerated 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 magne tic or abrasive tape wear, which typically occurs during the first fiv e to ten tape passes. Microscopic examination using scanning electron microscopy indicates that this reduction in wear rate is not due to cl ogging of the abrasive tape but rather to changes in abrasive particle shape. This means a recording head subjected to continuous sliding wi th fresh tape will wear considerably faster than a head which slides r epeatedly against a loop of tape. Accordingly, in reporting the wear r ates of head materials, it is important to describe the corresponding tape condition or usage history explicitly.