The effect of cutting parameters on micro-hardness and the prediction of Vickers hardness based on a response surface methodology for micro-milling Inconel 718

Abstract

The poor characteristics of Inconel 718, such as large plasticity, low thermal conductivity, and sensitivity to the strain rate, lead to serious problems in its micro-milling, particularly its work hardening, which lowers the fatigue and the corrosion resistance of micro parts and accelerate tool wear. Therefore, the studies pertaining to work hardening caused by micro-milling of Inconel 718 are needed. This paper studies the influence of cutting parameters, including the spindle speed, the feed rate per tooth, and the axial cutting depth, on surface Vickers hardness and predicts the Vickers hardness of the machined surface on Inconel 718. The authors adopt response surface methodology to build the Vickers hardness prediction model and rank the parameters based on their influences on surface Vickers hardness of micro-milled Inconel 718. According to our analyses, the spindle speed has themost influence on Vickers hardness, the axial cutting depth has an intermediate influence, and the feed rate per tooth has the least influence. A significant interactive influence between the spindle speed and the feed rate per tooth exists. The study could support the appropriate selection of cutting parameters in improving the characteristics of surface work hardening thereby the quality of the final product.