Non-Invasive Estimation of Machining Parameters during End-Milling Operations Based on Acoustic Emission

. 2020 Sep 17;20(18):5326. doi: 10.3390/s20185326

AE	Acoustic Emission
a_e	Radial depth of cut, mm
a_{e_i}	Axial depth of cut, mm
a_{p_i}	Axial depth of cut of the flute i, mm
a_{p_a}	Actual axial depth of cut, mm
$φ$ _en	Entry angle, rad
$φ$ _{en_i}	Entry angle of flute i, rad
$φ$ _pr	Projected angle of the cutting edge, rad
F_x	Cutting force in X direction, N
T	Period of spindle rotation, s
D	Tool diameter, mm
f_z	Feed per tooth, mm
n	Spindle speed, rpm
N	Tool flute number, -
$λ$ _s	Tool helix angle, rad