Wear behaviour of CBN tool when turning hardened AISI D3 steel

Abstract

Investigations on wear resistance of cubic boron
nitride tool during turning of hardened AISI D3 steel have
been conducted. Initially, long term wear tests were
planned to elucidating the effects of cutting speed on the
various forms of CBN tool wear and also to make in evidence
wear consequences on the tool life and the productivity.
Then, a second series of experiments has been carried
out to study the influence of wear (VB) on surface
roughness, cutting force and temperature. Results show
that the CBN tool presents a good wear resistance despite
the aggressiveness of AISI D3 steel (60 HRC). A great part
of heat generated during cutting is dissipated within the
chip. Beyond 240 m/min cutting speed, the machining system
becomes unstable, producing sparks and vibrations
caused by intensive wear evolution. Meanwhile, up to the
admissible wear value [VB] =0.3 mm, roughness Ra did
not exceed 1 μm but beyond, roughness increased, but it
remained extremely acceptable (Ra <1.2 μm). Finally, in
one hand a mathematical model has been obtained to predict
the tool life as a function of the cutting speed and in
the other hand a correlation between roughness Ra and
wear VB is proposed.