Table 2.

Main data of drill bits for all tests.

Code	Material	Coated	Point Angle	Helix Angle	Web Thickness (mm)	Margin (mm)	Body Clearance (mm)
B1	HSS	–	130°	35°	1.25	0.43	0
B2	WC	TiAlN	140°	27°	1.9	0.40	0
B3	WC	Diamond Tip	90°	35°	2	0.22	0.16