Effects of grit size on abrasion with coated abrasives

Abstract This paper is concerned with identifying the causes of grit size effects in the initial performance of fresh coated abrasives and the deterioration of coated abrasive performance with continued use. Abrasion tests were performed on an instrumented pin-on-cylinder apparatus which had removable segments for observing the coated abrasive surface in the scanning electron microscope (SEM). This allowed for a direct correlation between measurements of coated abrasive performance and SEM observations of coated abrasive morphology. With coated abrasives containing finer grit sizes, numerous adhesive wear particles were found on the coated abrasive surface; this supports the theory that the smaller initial abrasion rate with finer grits is due to abrasive grains making “elastic” contact with the metal specimen at loads insufficient for cutting. With continued use, the rapid deterioration in performance with finer grits was accompanied by a buildup of metal caused by capping of the abrasive grain tips with metal chips and by clogging due to metal chips and adhesive wear particles becoming stuck between the grains. With coarser grits, which were found to experience extensive grain fracture followed by some grain capping and flattening but virtually no clogging, the deterioration in coated abrasive performance was very much less.