Analytical, numerical and experimental study of cutting force during thermally enhanced ultrasonic assisted milling of hardened AISI 4140

Abstract

Two advanced machining methods as thermally enhanced machining and ultrasonic assisted machining has been considered in many studies, recently. In this paper, a new hybrid milling process is presented by gathering the characteristics of these two methods. A special experimental setup is applied and numerical and analytical models are developed to predict cutting force during the hybrid process. 3D thermal finite element analysis is applied to determine the axial depth of cut and engagement (the radial depth of cut) by measuring the dimensions of softened material. Full factorial experimental design is applied to investigate the effect of hybrid machining parameters on the mean cutting force. 2D finite element model is developed to predict the mean cutting force of the hybrid milling process. The analytical model is developed based on chip thickness as well as consideration of thermal softening of the material caused by the concentrated heat source. Major events in numerical and analytical models are external concentrated heat source and ultrasonic vibrations that are implemented successfully. According to the results, the application of thermally enhanced ultrasonic assisted milling on hardened AISI 4140 with the amplitude of 10µm and temperature of 900°C could reduce cutting force about 27% in comparison to conventional milling with feed of 0.063mm/tooth. Experimental results presented a good agreement with numerical and analytical methods which can show the ability of developed methods to predict mean cutting force.