Experimental Investigation of Cryogenic Cooling in Milling of AISI D3 Tool Steel

The application of a conventional cutting fluid in the milling process may not effectively control the heat generation, which also leads to a serious threat to the environment and the operator's health. Cryogenic machining using liquid nitrogen is an environmental friendly approach for the desirable control of the cutting zone temperature. This article attempts to present the experimental investigations of the influence of cryogenic cooling by liquid nitrogen (LN2) jet on the performance in the milling of hardened AISI D3 tool steel with TiN coated carbide inserts. Experiments have been performed at constant speed (125 m/min) and three different feed rates in the range 0.01-0.02 mm/tooth. In LN2 machining, the cutting temperature was reduced by 43-48% and 26-35%, and the mean cutting force decreased by 40-50% and 22-39% over dry and wet machining. The effective penetration and high potential cooling effect of LN2 on the tool-chip interface forms a lubrication layer when the cutting temperature is lowered, which results in improved surface finish and tool life.