On the properties of PVD coating based on nanodiamond and molybdenum disulfide nanolayers and its efficiency when drilling of aluminum alloy

Large burrs were formed when uncoated drills were used. In the case of using coated drills the vast majority of holes did not show any burrs or the sizes of the burrs were considerably smaller. The number of holes with burrs increased slightly with the drilling time. The built-up edges were formed along the major cutting edges of the drill. The intensity of built-up formation varied and depended on the drills used: the uncoated drills have built-up edges to a significantly greater height than the drills with the coating. Pickups are formed at the area of the drill chisel edge and at drill flutes and pickup sizes are more significant for the uncoated drills. The VB value of the flank surface wear for the uncoated drill was significantly higher as compared to the coated drill. The tool life of coated drill was found to be approximately 2.5 times longer in comparison with the uncoated drill.