Cl	Lateral crack length (μm)
α	Dimensionless constant
φ	Half angle of the abrasive tip (°)
E	Elastic modulus of the material (GPa)
K IC	Fracture toughness of the material (MPa·m1/2)
H v	Hardness of the material (GPa)
F an	Axial force exerted on a single abrasive particle (N)
F n	Axial force exerted on the cutter (N)
v f	Workpiece feed rate (μm/s)
n 0	Rotation speed of trepanning cutter (r/min)
D	Outer diameter of the trepanning cutter (mm)
d	Inner diameter of the trepanning cutter (mm)
m	Effective number of abrasive particles involved in machining
R z	Maximum distance between the peak and valley depth on the micro profile of the measured workpiece surface (μm)
S a	Surface roughness of the hole wall (μm)
C m	Median crack depth generated by a single abrasive particle pressing into a brittle material (μm)
ε	Proportional constant independent of material properties
d s	Exit-chipping width (mm)