Optimization of dry machining parameters for high-purity graphite in end milling process via design of experiments methods

This investigation applied the designs of experiments (DOE) approach to optimize parameters of a computer numerical control (CNC) in end milling for high-purity graphite under dry machining. The groove difference (i.e., dimensional accuracy of groove width) and the roughness average at the bottom plane of the inside groove (i.e., the plane of end milling) were studied. Planning of experiment was based on a Taguchi orthogonal array table. The analysis of variance (ANOVA) was adapted to identify the most influential factors on the CNC end milling process. Simultaneously, applying regression analysis a mathematical predictive model for predictions of the groove difference and the roughness average has been developed in terms of cutting speed, feed rate, and depth of cut. The feed rate is found to be the most significant factor affecting the groove difference and the roughness average in end milling process for high-purity graphite. Additionally, the tool worn surfaces after machining were examined by the optical zoom scope (OZS).