Surface roughness model for end milling: a semi-free cutting carbon casehardening steel (EN32) in dry condition

This paper describes the development process of a surface roughness model for the end milling EN32M (a semi-free cutting carbon casehardening steel with improved merchantability). This steel can be carbonized and hardened to produce a hard wear resistant case, with core strength of approximately 460 N/mm2, and 160 BHN steel. Typical applications include cams, rollers, spindles, pins, etc. These materials are generally difficult to machine. The mathematical model for the surface roughness has been developed, in terms of cutting speed, feedrate, and axial depth of cut. The effect of these cutting parameters on the surface roughness has been carried out using design of experiments and the response surface methodology (RSM). A first-order equation covering the speed range 30–35 m/min and a second-order generation equation covering the speed range 24–38 m/min were investigated in dry condition.