Wear mechanism and notch wear location prediction model in ball nose end milling of Inconel 718

This study is an investigation of tool wear using a ball-type end mill. The primary purpose of this work is to examine the tool life and wear mechanism when machining Inconel 718 with a physical vapor deposition (PVD)-coated carbide tool and varying the cutting parameters. Notch wear and flaking near the depth of the cut zone were the predominant types of tool failure for the four round cutting tools and were initiated by pitting caused by the repetitive cyclic load. The major factor identified was the large radial depth of the cut. Further examination indicated that the dominant wear was located near the depth of the cut line. On the flank face, smooth and coarse wear types, from abrasion and attrition, occurred at low and high cutting speeds, respectively. A maximum temperature of 521 °C was recorded, which is less than the critical temperature of 650 °C for Inconel 718. A mathematical model was developed to predict the location of the pitting, which was responsible for notching and flaking. This location could then be used to calculate the location associated with the maximum load exerted during the cutting. The error between the predictive model of pitting and the actual notching/flaking was less than 6%.