Performance of PCBN tools in dry cutting iron-based superalloy

Abstract

A range of PCBN tools were utilized for turning iron-based superalloy in dry environment and their cutting performance was researched from the perspective of tool wear, tool life, cutting force, cutting temperature, and machined surface roughness. The experimental results revealed that the cutting temperature increased, while the resultant cutting force exhibited an initial rise followed by a decline as the cutting speed increased. The PCBN tools with TiC or TiC+SiCw ceramic bonding agent and low CBN content (≤65 %) were chipped and even fractured in the preliminary stage of the cutting process and were not suitable for cutting the iron-based supperalloy. The PCBN tools with Co-W-Al ceramic bond agent and high CBN content (85 %) performed well in the cutting process, while for every 50 m/min increase of cutting speed, tool life was reduced by approximately a half. An exceptional surface quality could be achieved using this specific type of PCBN tools. However, once the wear value of the flank faces reached about 0.25 mm, the surface roughness began to increase noticeably. In order to achieve higher surface quality, the suggested cutting time for continuous dry cutting iron-based superalloy using the PCBN tools at different cutting speeds was obtained. Rake face wear was dominated by adhesion, chipping, flaking and grooving, and built-up-edge and microcracks also appear at relatively higher cutting speed. Flank face wear showed brittle flaking off at the lower cutting speed (50 m/min), while when cutting speed was increased (100 m/min-200 m/min), abrasion and adhesion wear were dominant.