Effect of Milling Parameters on Chip Characteristics of a (Mg-Zn-RE) Magnesium Alloy

The Magnesium (Mg) alloys containing rare earths (RE), have gained prominence due to their low density and high specific strength. However, the effects of machining parameters on chip formation are not fully understood. In this context, this study aims to investigate the influence of milling conditions (milling mode, edge radius, feed rate, and depth of cut) of the (Mg-Zn-RE) Mg alloy on the characteristics of the chips, with regard to morphology, thickness, microstructure, and hardness. Sixteen cutting conditions were evaluated, combining two milling modes, two edge radius (rβ) levels, two feed rate (f) levels, and two depth of cut (ap) levels. The analysis involved the use of characterization techniques such as optical microscopy (OM) and Vickers microhardness (HV). Results indicate that conditions with ap = 2 mm generate arc-shaped chips, and ap = 1 mm tend to be comma-shaped, while discordant conditions significantly influence chip fragmentation. Higher f (0.8 mm/rev) and up-milling increase chip thickness. Microstructural analysis shows increased precipitate density and plastic deformation, reflecting work hardening. Although microhardness was not significantly altered by the cutting parameters, conditions under discordant cutting and a smaller f (0.01 mm) produced harder chips, and in comparison, with the material “as received,” there was a significant increase in the microhardness of the chips.