Performance Evaluation of Minimum Quantity Lubrication (MQL) using CBN Tool during Hard Turning of AISI 4340 and its Comparison with Dry and Wet Turning

In order to increase the flexibility and ability to manufacture complex geometry, hard turning was introduced where the necessity of grinding operation can be eliminated. In hard turning rough machining, final grinding can be eliminated and raw material is supplied in the final heat treated condition. Hard turning can seriously be regarded as an alternative for grinding operations under certain circumstances. Generally hard turning requires large quantities of coolants and lubricants. The cost of associated with lubricants increases the total cost of production considerably. Conventional cutting fluid application fails to penetrate the chip-tool interface and thus cannot remove heat effectively. Considering cost and the stricter environmental laws are enforced, alternatives has been sought to minimize the use of cutting fluid in machining operations. Some of these are dry machining and machining with Minimum Quantity Lubrication (MQL). Present work deals with the comparative performance of CBN tool in machining AISI4340 steel in conventional dry and wet turning with Minimum Quantity Lubrication by varying speed and feed, depth of cut. The experiments were conducted using standard L18 (2 1 x3 7) mixed orthogonal array. Statistical analysis was performed using MINITAB software for ANOVA analysis, mean effects and interaction plots.