3.5.2. T2—Wear Mechanism Analysis

As observed in the case of T1, for this case the wear was also noticeable with the increase in cutting length. Regarding the wear mechanisms previously reported in the T1 tool, these were also present in T2; however, there were different severities. For example, in the case of the amount of adhered material, this was more severe in T2 than that observed in T1. The main wear mechanisms sustained by these tool types were abrasion, material adhesion, coating delamination and some coating cracking, as seen in T1, albeit at different levels.

As described in the section regarding the wear measurements performed on these tools, they exhibited more wear for longer cutting lengths; however, this wear was not as significant as recorded for the previous tools. Contrary to what was seen in T1, adhesion started to form at lower cutting lengths, as seen in Figure 10.

**Figure 10.** Adhered material in the T2 tool's flank, tested under the T2L2F100 condition.

This adhesion was registered in the coating's clearance and rake faces, forming primarily at lower feed rates. This adhesion to the tool's coated surface eventually leads to coating delamination by adhesive wear, as seen in Figure 11, where zones of adhered material are marked in yellow.

**Figure 11.** Coating delamination registered in the rake face of a T2L2F100 tool.

At higher feed rates, primarily at a 125% feed rate, the amount of adhesive wear was lower than that registered at lower feed rate values. However, the tools presented abrasion marks and cracking, exhibiting high levels of wear as well. In Figure 12, the abrasive wear can be observed in a T2 tool, tested at a 125% feed rate. The coating was abraded, exposing the substrate. However, there was some coating delamination, especially in the tool's rake face, possibly caused by adhesive wear, as shown in Figure 13.

**Figure 12.** Abrasive wear on the clearance face of T2L4F125 tool.

**Figure 13.** Rake face of a T2 tool tested at 4-m cutting length and 125% feed rate showing adhesive wear and coating delamination.
