Influence of ultrasonic vibrations on side milling of AISI 420 stainless steel

Characteristics of one-dimensional ultrasonic-assisted side milling of AISI 420 stainless steel have been investigated in this paper. Cutting force in ultrasonic-assisted milling (UAM) has been modeled, and new relations for critical cutting speed and undeformed chip thickness have been presented. Based on analytic relations, it can be inferred that in successive end mill revolutions, contrary to conventional milling (CM), cutting forces in UAM have different magnitudes. In order to experimentally investigate the cutting forces and the workpiece surface roughness, CM and UAM processes have been applied and compared in certain cutting conditions. Experimental results indicate that the average of cutting forces in UAM is less than in CM, and depending on cutting parameters, workpiece surface roughness in UAM can improve. During small value of feed, the influence of ultrasonic vibrations on the decrease of cutting forces is more noticeable in up milling, while during larger feed, employing UAM is more effective in down milling. It seems that for low feed rates, high cutting speeds and up milling process, the effect of ultrasonic vibrations on the surface roughness is more noticeable.