PSI - Issue 53

A. Teixeira et al. / Procedia Structural Integrity 53 (2024) 352–366 Author name / Structural Integrity Procedia 00 (2019) 000–000

362

11

Fig. 15. Wear observed at the chip breaker and tool’s flank after machining: (a) SEM image of the tool’s tip and rake face, exhibiting abrasive wear, and exposed substrate; (b) digital microscopy image of the tool’s flank, exhibiting material adhesion; (c) SEM image of the tool’s flank; (d) magnification of the adhered material on the tool’s flank. As previously mentioned, Fig. 15. depicts the main wear mechanism that were observed in the tested tools, however, it was noticed that in some cases there was BUE formation, caused due to the excessive adhesion of machined material. However, this was not documented for all cases, and it was not considered severe. 3.3. Surface roughness The integrity of the machined surface is crucial in finishing turning operations. Surface quality is mainly dependent on surface roughness and defects occurrence on the machined surfaces. Every time the tests were paused, the workpiece’s surface roughness, arithmetic average roughness, R a , and average maximum peak-to-valley height, R z , were measured to assess how tool wear affects the workpiece’s surface quality. Three measurements were made, and the average values obtained were plotted in Figs. 16 and 17. As expected, and confirmed by the experimental results, larger feed rates lead to an increase in the value of surface roughness (above 3 µm), due to the increase in the separation between feed marks. Also, the increase in the cutting load to the cutting edge for higher feed rate vales induced more severe plastic deformation resulting in a higher surface roughness (Hua & Liu, 2018).