EFFECTS OF LIQUID NITROGEN ON CRYOGENIC MACHINING OF AISI D2 HARDENED STEEL

The milling of hardened steel generates very high temperature in the cutting zone, and leads to detrimental effects on the cutting force, workpiece surface finish and tool life. Cryogenic machining is an environmental friendly new approach for the desirable control of the cutting temperature in the cutting zone. The present work investigates the effect of cryogenic cooling by liquid nitrogen (LN2) on the cutting temperature, cutting force and workpiece surface roughness on the end milling of AISI D2 steel by CVD TiN coated carbide insert, at a constant cutting speed of 100 m/min and varying feed rate in the range of 0.01-0.02 mm/tooth. The experimental results showed that with LN2 as a coolant the cutting force and workpiece surface roughness were reduced compared to dry and wet machining due to the better lubrication and cooling effect through reduction of cutting zone temperature.