Jc. Rozzi et al., Transient, three-dimensional heat transfer model for the laser assisted machining of silicon nitride: II. Assessment of parametric effects, INT J HEAT, 43(8), 2000, pp. 1425-1437
In a companion paper (J.C. Rozzi, F.E. Pfefferkorn, F.P. Incropera, Y.C. Sh
in, Transient, three-dimensional heat transfer model for the laser assisted
machining of silicon nitride: I. Comparison of predictions with measured s
urface temperature histories, International Journal of Heat and Mass Transf
er 43 (2000) 1409-1424), experimental validation was provided for a transie
nt, three-dimensional heat transfer model of the LAM of a silicon nitride w
orkpiece. In this paper, the model is used to elucidate the influence of op
erating parameters on thermal conditions within the workpiece. Calculations
reveal that thermal energy generation in the primary shear zone has a sign
ificant influence on the workpiece temperature distribution, while the effe
cts of heat transfer at the tool flank interface may be neglected. Although
temperatures at the material removal plane were only moderately influenced
by an increase in the workpiece rotational speed, a reduction in total las
er energy deposition due to increased laser/tool translational velocity or
decreased laser power may preclude the attainment of a minimum material rem
oval temperature corresponding to the softening temperature range of the YS
iAlON glassy phase. Due to the comparatively small influence on radial temp
erature gradients within the material removal plane, the minimum material r
emoval temperature decreased only slightly with increasing depth of cut. Ho
wever, the amount of laser energy deposition on the unmachined workpiece in
creased significantly with increasing laser-tool lead distance, yielding an
attendant increase in the material removal temperature. For a fixed laser-
tool lead, energy deposition at the unmachined workpiece surface increased
with decreasing laser beam diameter and increasing power. (C) 2000 Elsevier
Science Ltd. All rights reserved.