*1.1. Tool Wear Mechanisms in CFRP Drilling*

The conventional drilling process of CFRP involves continuous interaction between the tool and two types of materials. One is more plastic (matrix) and easily meltable at low temperatures, which can cause its thermal fixation to the tool. The other one, of higher hardness, is discontinuous in the matrix such as carbon fibre (CF); it is easily breakable and its particles (interacting with the edge, the release face and the evacuation channel of the drill bit) act in an abrasive way (Figure 1).

**Figure 1.** Evacuation of the composite material by dry OSD.

The abrasive action occurs in two different ways:

