Polycrystalline Cubic Boron Nitride (PCBN) Tool Life and Wear in Turning of Amorphous-Crystalline Iron-Based Coatings

Abstract

The paper presents PCBN-Ciborit cutting tools life and wear test results. The effects of the machining regime when turning amorphous-crystalline Fe80B20 and Fe79Cr16B5 coating systems applied to conventional workpiece materials were assessed. It has been shown that the observed tool wear mechanisms are complex in their character and are dominated by abrasive-mechanical, adhesive and chemical effects in the cutting zone. Under changing turning conditions tool life is affected by the structural-phase composition and by the non-homogeneous structure of the coating. Specifically, when turning gas-flame coatings deposited with a Fe80B20 electrode and electro-arc coatings with a Fe79Cr16B5 electrode the lowest wear and the highest tool life was achieved at cutting speeds of nu = 1.1 to 1.2 m/s and a back rake angle of gamma = -10 degrees It has been demonstrated that a change of the back rake angle from gamma = 0 to -10 degrees does not have a great effect on tool life contraty to the case with gamma = -20 degrees.