nac	Actual number of contacting grains
Aos	Amplitude of the vertical oscillation
Ra	Arithmetic mean deviation of the assessed profile (surface roughness)
$P_x^{/}$	Axial component of the cutting force acting on one grain
vb	Belt speed
T	Belt tension force
Gbond	Bond shear modulus
$I_M$	Calculated machinability index
Pc	Clamping force
φ	Contact angle
∪AB	Contact arc angle
Fc	Contact area
ap	Cutting depth
P	Cutting force
vc	Cutting speed
ρ	Density
$a_p^{/}$	Depth of cut for one cutting grain
ß	Deviation angle of the cutting grain from the vertical position during grinding
τi	Duration of the i-th grinding (tool life)
$I_M^{ex}$	Experimental machinability index
$V_B\left(\tau \right)$	Grain blunting area, which changes during machining
$V_B$	Grain blunting area (flank wear)
c	Grain bonding
h	Grain protrusion from the bond
b	Grain width
HB	Hardness
$b_g^{/}$	Height of a single grain
${\overline{I}}_M$	Machinability index of a material group
Pz max	Maximum tangential component of the cutting force
n	Number of grinding sequences
τ	Operating time of the tool till the resistance criterion (tool life)
$q_{Per}$	Performance index
$q_{Per}\left(x\right)$	Performance index of metal grade
$q_{Per}\left(45\right)$	Performance index of steel 45
p	Pressure
$P_y^{/}$	Radial component of the cutting force acting on one grain
Py	Radial cutting force
vr	Roller speed
R	Roller radius
P/	Specific cutting force acting on one grain
$\epsilon$	Strain intensity
$\dot{\epsilon }$	Strain rate
σi	Stress intensity in the shear zone of the material being machined
$P_z^{/}$	Tangential component of the cutting force acting on one grain
$T^0$	Temperature
$F_B$	The area of the bond between the adjacent grains
$K_1$; $K_2$	The coefficients accounting for the geometry of the cutting part of abrasive grains and the nature of metal yielding in the deformation zone
$C_x; C_z$	The coefficient of elastic uniform compression of the bond horizontally and vertically
$q_i$	The material removal over the i-th grinding period
$b$	The minor axis of the ellipse or the minimum grain size
$\mathsf{\Delta }\phi$	The minor turning angle of the grain near the axis of mass under the action of force $P_1$
$V_B^{/}$	The width of the area of wear
σD	Ultimate Stress
wos	Vertical oscillation frequency
vw	Workpiece speed
σy	Yield Stress