THERMAL DAMAGE DURING GRINDING OPERATIONS OFTEN LIMIT THE PRODUCTION RATE IN MODERN GRINDING. THIS PAPER DISCUSSES THE PHENOMENON OF THERMAL DAMAGE DURING THE GRINDING OF A NUMBER OF CARBON STEELS. A SPECIAL WEDGE GRINDING TEST WAS USED TO MAP AND GRADE THE DEGREE OF THERMAL DAMAGE ASSOCIATED WITH THE ABOVE WORK MATERIALS. TRUE MATERIAL REMOVAL, HARDNESS CHANGE, BUILD-UP OF NEW PHASES, EXTENT OF FORM CHANGE, GRINDING BURR AS WELL AS RESIDUAL STRESSES WERE USED TO IDENTIFY THE DEGREE OF THERMAL DAMAGE. THE CONCEPT OF CRITICAL CONTACT TIME IS PROPOSED TO QUANTIFY DAMAGE LEVEL.