Machining characterization and optimization under different cooling/lubrication conditions of Al-4Gr hybrid composites fabricated by vacuum sintering

In this study, the effects of different cooling/lubrication strategies and cutting parameters during milling hybrid composites based on Al-4Gr, a new material, were investigated. The main matrix was formed by adding Gr at a constant rate (4%) to Al. Hybrid composites were fabricated by vacuum sintering by adding WC and Al2O3 in different ratios (2-4-8 wt.%). Environmentally friendly cryogenic liquid nitrogen (cryo-LN2) and minimum quantity lubrication (MQL) fluids were used as cooling and lubricating environment in the milling process. Three different cutting speeds (150, 225, 300 m/min), three different feed rates (0.150, 0.225, 0.300 mm/rev) and a single depth of cut (0.5 mm) were selected for milling. Surface roughness, flank wear, cutting temperature, and chip morphology were evaluated for different cooling/lubrication environments. As a result, the cryo-LN2 environment reduced the surface roughness, flank wear, and cutting temperature by 34.9%, 18.5%, and 69.5%, respectively, compared to the dry medium. Adhesion wear was reduced in MQL and cryo-LN2 environments. In addition, it was determined by the analysis of variance that the most effective factor among the response parameters was cooling/lubrication. The cooling/lubrication environment has an effect of 74%, 58%, and 94% on surface roughness, flank wear, and cutting temperature, respectively.