ADVANCED CERAMIC TOOLS, WITH ENHANCED RELIABILITY, ARE INCREASING PRODUCTIVITY IN MACHINING SUPERALLOYS. THE CHOICE OF CUTTING TOOL MATERIAL IS CRITICAL FOR MAXIMIZING PRODUCTIVITY IMPROVEMENTS. SIALONS PROVIDE HIGH TOUGHNESS AND THERMAL SHOCK RESISTANCE, WHEREAS THE SIC-WHISKER- REINFORCED ALUMINA TOOLS HAVE ENHANCED WEAR RESISTANCE. THESE BASIC MATERIAL PROPERTIES HAVE BEEN EXPLOITED BY APPLYING SIALONS FOR ROUGH TURNING, INTERRUPTED CUTTING, AND MILLING OPERATIONS. AL203-SICW TOOLS, ON THE OTHER HAND, ARE BEST SUITED FOR HIGH-SPEED FINISHING OR SEMI-FINISHING APPLICATIONS. A DISCUSSION OF METALCUTTING TEST RESULTS INDICATES THAT A CAREFUL ANALYSIS OF MACHINING VARIABLES IS NEEDED BEFORE ONE OR BOTH OF THE ADVANCED CERAMIC TOOL MATERIALS MAY BE RECOMMENDED TO YIELD OPTIMUM PERFORMANCE.