The effect of abrasive properties on the surface integrity of ground ferrous materials.
The effect of the thermal properties of alumina and CBN abrasives on workpiece
temperatures in grinding was investigated. A review of the literature revealed a lack of
knowledge of the thermal properties of CBN limiting the accuracy of theoretical
predictions of the heat conduction in CBN grinding.
A grain contact analysis was developed to predict the energy partitioning between the
workpiece and wheel. The analysis takes into account two dimensional transient heat
transfer in the grain and maintains temperature compatibility at the grain wear flatworkpiece
The proportion of the total grinding energy entering the workpiece, termed the partition
ratio, was estimated by correlating measured temperature distributions with theoretical
distributions. The partition ratios when grinding with CBN were substantially lower than
grinding with alumina wheels for a range of ferrous materials. The lower partition ratios
with CBN grinding were attributed to the higher thermal conductivity of the CBN
abrasive. The effective thermal conductivity of alumina and CBN grains were quantified
by correlating the theoretical partitioning model with the measured results. The effective
thermal conductivity of CBN was found to be considerably lower than the reported
theoretical value albeit much higher than the effective thermal conductivity of alumina.
A model to predict the background temperature in grinding was proposed based on the
experimental findings. The thermal model takes into account a triangular heat flux
distribution in the grinding zone, the real length of contact and experimentally validated
grain thermal properties. The input parameters to the thermal model were specified. To
avoid temper colours on the workpiece surface the maximum background temperature
must not exceed 450 to 500deg. C. for commonly used ferrous materials.