Investigation of the machinability by milling of the laser sintered Inconel 625/NiTi-TiB2 composite

OBRABOTKAMETALLOV Vol. 23 No. 1 2021 TECHNOLOGY а b Fig. 9. Photo of the wear of the mill No. 3 on the rake ( a ) and fl ank ( b ) surface Fig. 10. Application of point force for different depth to width ratios The diagram shows that with the depth to width ratio of 1:1, the lever of the concentrated force l 1 = 23 mm is greater than the lever l 2 = 20 mm, with a ratio of 1:16. Therefore, the bending moment acting on the fi rst mill is greater. For mill No. 1, the bending moment is M 1 = 2.75  Nm, and for mill No. 3, M 3 = 2.26 N  m. To calculate the bending moment, the force value is obtained from the experiment, and the lever of the acting force is determined according to the scheme shown in Fig. 10. The bending moment of the fi rst mill is almost 20% greater than that of the third. This leads to a greater vibrations amplitude as well as to the mill vibrations and increases its wear. After reaching the critical value of wear, the force increases sharply, while the difference in bending moments becomes even greater. Another reason for excessive wear may be the temperature distribution in the cutting area. For example, with a small width and a large milling depth, the temperature during the cutting process is localized on a small area of the tool [17], which causes an acceleration of the wear process. As the milling width increases, the temperature is distributed over the longer length of the mill cutting part thus reducing the wear rate.