Comparative machinability performance of heat treated 4340 Steel under dry and minimum quantity lubrication surroundings

Finish hard turning using coated carbide tools of various layers of coating under different environments of machining process has been raised as a new technique in the field of machining by report to the conventional rectification and to be extensively treasure-trove its utilization manufacturing industry. To achieve a better life of the insert and a better finishing the surface temperature at the cutting area must be controlled, which could be achieved by machining under MQL state. Therefore an experimental survey was conducted on various aspects of the machinability such as wear of the insert and average quality of the machined surface utilizing multilayer coated carbide insert in the turning of the hardened AISI 4340 under the state dry and MQL. The detailed investigation has revealed that multilayered coated carbide insert has generated a good surface quality and executed in the scope of the recommended level of 1.6 microns under the two environments. It was confirmed that the abrasion is the main mechanism of wear under the both conditions of machining. Inserts made of carbide multilayer coated gave satisfactory performance in the MQL state in relation to the dry state. The surface finish was also higher in the MQL condition rather than dry. Cutting speed has been the most imperative process parameter regarding the wear on the flank surface and the speed predominates on the roughness of the turned surface.