Evaluation of tool life and workpiece surface roughness in turning of AISI D6 hardened steel using PCBN tools and minimum quantity of lubricant (MQL) applied at different directions

Abstract

The main objective of this work is to evaluate the tool life and the workpiece surface roughness when applying a vegetable-based cutting fluid by minimum quantity of lubricant (MQL) at three different directions (main tool flank face, secondary tool flank face, and overhead) in turning AISI D6 hardened steel with polycrystalline cubic boron nitride (PCBN) tools with Al2O3 ceramic binder and TiN coating. Dry cutting was also tested for comparisons. Tool wear analyses were performed on the tools at the end of their lives within a scanning electron microscope (SEM). The application of the cutting fluid by MQL technique in the direction between the main tool flank face and the workpiece showed better results than the dry condition. The application of MQL through other directions (overhead and between the secondary tool flank face and the workpiece) also showed competitive results. Abrasion and adhesion were the prevailing mechanisms for the wear of the tools.