Chip formation analysis while drilling Al–Mg-Si 6061-T6 alloy using high-speed steel drills with and without DLC

Abstract Chip formation has a significant influence on the drilling process in aluminum alloys, directly affecting hole quality, tool life, cutting forces, and workpiece heating. One of the main challenges in drilling is related to material removal, which is heavily constrained by the drill’s chip evacuation channel. This condition can negatively impact the surface finish of the machined workpiece. Applying thin films, such as Diamond-Like Carbon (DLC), can help chip removal and improve the tribological properties of the tool surface, contributing to reduced friction, lower tool wear, and increased tool life. This study, two DLC coatings (Type A and B) were deposited on cutting tools made of AISI M2 high-speed steel with the aim of obtaining improvements during the dry drilling of the Al–Mg-Si 6061-T6 alloy compared to the uncoated tool, evaluating chip formation as a response variable. Three machining groups were established, each using a single cutting tool to machine 1,120 holes. Chip samples were collected to characterize chip formation in terms of type, shape, chip compression ratio, and cross-sectional microhardness. The results showed continuous-type chips with a predominantly conical-helical shape. Statistical analysis indicated that the DLC coating caused a significant change in the chip compression ratio. A potential relationship between microhardness and chip compression ratio was also observed.