WEAR OF COATED CARBIDE TOOLS WHILE MACHINING 18-8 AUSTENITIC STAINLESS

Abstract

Austenttic stainless steels of 18-8 type are being used widely in all types of industries. Some of its mechanical and chemical "properties make it a difficult to magch1ne material than carbon and bother alloy steels. It has a tendency of excessive work-hardening, chip tool adhesion. It's. high coefficient of thermal expansion and low thermal conductivity create problems in machining. Some,new coated carbide tools have been developed to meet the demand of high speed machining of hard-to-machine materials. As the literature survey reveals that not much work has been done on these new tools particularly at high speed machining of Austentic stainless steel. This work had, therefore, been undertaken to compare the wear of these new tools with the conventional grades of carbides. The experinentation on the 4IDALON TK 15 insert has shown that it has much longer tool life than other grades. This tool is particularly effective in machining at high speeds (300 m/min or more) . The double coated TN exhibits good wear resistance upto 22D m/min while the uncoated TH 10 wears rapidly even at l5O m/min . The principal mechanism of wear in TK 15 is abrasion with shallow chip notching. The tool TN shows well built primary and secondary grooving with plastic deformation at high speeds. In case of TH 10 breakage of side cutting edge at the nose and flank takes place parti-cularly at high speed.