# Application of 3D Imaging for Analyzing the Chip Groove Shapes of Cutting Inserts
## 3 Results and Discussion
A comparative analysis of the measurement results showed that higher values were obtained for inserts with an SGF chip former than  
Figure 5: Comparison of the measurement results of the theoretical tool-chip contact length _Lch_ with the SGF and SF chip-former profile. (**a**) Tool-chip contact length _Lch_ for inserts with the major cutting-edge angle \(K=60^{\circ}\). (**b**) Tool-chip contact length _Lch_ for inserts with \(K=90^{\circ}\). Figure 6: Examples of rake surface measurement results. (**a**) Theoretical chip flow surface on the insert surface. (**b**) Theoretical volume of the chip groove. for inserts with an SF chip former (from about 1.5 to more than 3 times higher) regardless of whether the major cutting-edge angle \(K\) was adopted. Figure 7 shows examples of the insert cutting-edge areas with vector maps. Analysis of the measurements showed that for the insert with the SF breaker behind the cutting edge, there was a slope of the breaker surface over a large area and that the flow of the created chip was in the direction parallel to the cutting edge moving into the chip groove. This surface shape promoted chip wrapping and chip evacuation away from the workpiece. This process was also facilitated by the steep slope of the back wall of the chip breaker (the longer length of the vectors is shown in Figure 7a). For higher feed rates, the back wall of the chip groove can also be used as a chip breaker. Moving the chip material against the back wall at a higher speed can cause stress build-up and cracks in the material. On the other hand, in the case of the insert with the SGF breaker, the vectors on the front and back surfaces of the chip groove had similar lengths and were directed in opposite directions. This indicates a strengthening of the chip-curling process. Figure 8 shows examples of chip photography obtained in the cutting tests of Inconel 625. For small depths of cut (\(a_{p}=0.25\) mm/rev) and feed rate (\(f=0.07\) mm/rev), the chips were in the form of a ribbon-like shape. With increased values of depth of cut and feed, an intensification of the process of chip curling (smaller distances between chip turns--Figure 8b) to a spiral form was observed (an example of a long spiral form of chips is shown in Figure 8c). Figure 9 shows an example of a microscopic photographs of the rake face of the inserts under testing, with visible marks (marked with a red line) obtained due to the friction of  
Figure 8: Photographs and cross sections of chips from the Inconel 625 workpiece material. (**a**) Chips when cut with the insert with the SGF breaker, with \(a_{p}=0.25\) mm and \(f=0.08\) mm/rev. (**b**) Chips when cut with the insert with the SGF breaker, with \(a_{p}=0.50\) mm and \(f=0.10\) mm/rev. (**c**) Chips when cutting with the insert with the SF chip former, with \(a_{p}=0.50\) mm and \(f=0.20\) mm/rev. Figure 7: Insert corner vector maps. (**a**) Rake face of the insert with the SF chip former. (**b**) Rake face of the insert with the SGF chip former. the chip against the cutting tool material. Analysis of the shape and surface of the marks showed a different direction of chip formation depending on the angle of the tool in relation to the workpiece material. For the major cutting-edge angle \(K=60^{\circ}\), within the range of the tested depths of cut, the formed chips filled the chip groove to a greater extent. In addition, the observed wear on the back wall of the chip former indicates an increased contribution of this surface to the chip-rolling process. Additionally, a comparison of chip-former types showed smaller wear surfaces for the SF type than for the SGF type. This indicates a higher intensity of the chip-rolling process. For a depth of cut \(a_{p}=0.25\) mm, the wear surface had an elongated shape and was largely parallel to the machined surface. It follows that for such depths of cut, the chip form can change and be characterized, for example, by larger distances between chip turns or a change from a helical to a ribbon form.