Experimental Investigation on Cutting Speed and Temperature Variations during Orthogonal Machining of AISI 4340 Steel using Mak Sherol B as Coolant under Mist Conditions

High production machining particularly of high strength and heat resistant materials is associated with generation of large amount of heat. Such high temperatures profoundly tend to cause dimensional deviation in the work piece and premature failing of the cutting tool. The cutting fluids remove the heat from the work-tool interface. One of the methods of supplying cutting fluid to the work piece (at the work-tool interface to be precise) is by using a mist generator that carries the soluble cutting fluid and mixes it with compressed air, making the cutting fluid to spray on the working area in the form of mist (suspension of liquid particles in air).This is a technique of Minimum Quantity Lubrication (MQL) where the wastage of cutting fluid as admissible in conventional flood type cooling is prevented. Also, the oil mist particles coming out at high velocities, in the form of fluid jets, when incident on the work-tool interface, reduce the working temperatures of the high temperature zones and consequently improve the tool life. The mist machining is also considered an environmental friendly approach over conventional machining. By comparing the machining parameters such as cutting temperatures, tool wear, chip shapes and surface roughness(of work) obtained by admitting the cutting fluid in the form of mist (MQL) and by conventional flood type machining (Wet Machining) and without admitting coolant(Dry Machining), on high strength alloy steels such as AISI 4340 grade Steel using carbide inserts , it is possible to experimentally investigate the most suitable and efficient type of machining in terms of optimization in machining variables, especially cutting temperatures, chip morphology and tool wear rate and other important factors like machining economy and environmental considerations.