Summary Tools of SIP, RD107 and RD110 were tested at 300, 420 and 600 fpm cutting speed with .10 in depth of cut and .010 in/rev feed on EN9 to .030 in flankwear in order to find the constants in the expression VTn = C for the three grades. The values of ‘n’ were found to be .51, .53 and .46 and the values of C to be 4550, 4720 and 3620 for SIP, RD107 and RD110 respectively. It was found that at 600 fpm the crater wear of SIP was about a third of the wear of the other two grades.