MACHINING PERFORMANCE AND WEAR MECHANISM OF TiAlN-COATED INSERT

Titanium Aluminum Nitride (TiAlN)-coated cutting tool inserts were subjected to turning of carbon steel at two cutting speeds (75 mm/min and 120 mm/min), whereas depth of cut and feed rate is kept constant at 0.5 mm and 0.06 mm/rev, respectively. The objective of this work is to investigate the microstructural changes on the flank of the insert and effect of cutting speed on the machining performance of the coated insert. Microstructural examinations revealed the following phenomenon during turning process; (i) two-way transfer of material on worn surfaces of the insert and workpiece, (ii) formation of mechanically alloying transferred material, (iii) plastic flow of coated material, and (iv) abrasion wear mechanism. Test results also show that the flank wear reduced as the cutting speed increased due to good oxidation resistance properties of TiAlN coating layer at high temperatures generated during turning process.