Effect of cutting speed on surface roughness and tool wear by using MQL while turning: A comprehensive study on hardened carburized steel machining

Abstract

Machining is a very important process in the manufacturing industries like automotive, aerospace, food industries etc. Hardened steel machining has gained much attention now a days because of it’s intense use in the manufacturing of bearings, gears, cams and shaft. In turning of hardened steel a rotating workpiece is machined using a fixed cutting tool placed in a definite angle. Machining of hardened steel with better surface finish is a difficult job. In most of the cases this machining process is carried out with coated carbide cutting tool. Almost in every machining process some unavoidable phenomena occurs which results in rough surface finish. In the contact surface of the cutting tool abrasion, adhesion, oxidation and even some diffusion, which act simultaneously and in proportions depending mainly on the temperature. Basically generation of excessive heat in the contact surface is the prime reason of the rough surface finish and cutting tool wear. So the main aim of a manufacturer is to overcome this problem of excessive heat generation so that the tool can be protected. Application of coolant in the contact surface of tool and workpiece could be a very efficient of machining. But implementation of flood coolant system in this process will require a huge amount of coolant which is not environment friendly. This thesis tends to find out the optimum cutting speed of a hardened steel at a definite angle in which a coated carbide cutting tool is placed. For reducing the temperature the MQL ( Minimum Quantity Lubrication) process is used and measures are taken so that the lubricant is introduced in the right place. For a efficient lubrication in MQL process the nozzle diameter and the air pressure in the pump should be specific. Calculations are done to find the definite values of the parameters related to the machining process which results in a smooth surface finish of hardened steel.