Machining hard and brittle materials is an underlying challenge for researchers. The appropriate machinability aspects of such materials are achieved with ductile regime machining (DRM), which is achieved with a controlled depth of cut, feed, and high cutting velocity. The thermal softening of the work material reduces the machining efforts. Suitably, scratch tests have been performed at different temperatures to determine the ductile–brittle transition load and the corresponding depth of cut. In this research work, with regard to adaptability to human anatomy, 45S5 bioglass samples are scratched at a fixed scratch speed, a ramp load, and varying sample temperatures from 27 ℃ to 700 ℃. Consequently, the effect of high temperature during the scratch on traction forces, hardness, critical load, and critical depth of cut has been analyzed. It is observed that a higher temperature helps to lower the traction force and increase the depth of cut at a particular normal scratch load and speed. Based on the results, a modified Bifano model for the determination of critical depth of cut is proposed to predict this parameter during the machining of 45S5 bioglass.