Coating-thickness-dependent physical properties and cutting temperature for cutting Inconel 718 with TiAlN coated tools

INTRODUCTION: Coating-thickness-dependent physical properties can induce different cutting temperatures with physical vapor deposition (PVD) titanium aluminum nitride (TiAlN) ceramic-coated tools. The determination of the optimal TiAlN coating thickness is important to obtain superior coating physical properties and decrease the cutting temperature of Inconel 718 alloy. OBJECTIVES: The present study investigates the effects of coating thickness on the physical properties of TiAlN coatings and the cutting temperature during the machining of Inconel 718 alloy. The optimal coating thickness is also determined. METHODS: First, the direct-current-arc method was utilized to deposit PVD Ti(0.55)Al(0.45)N coatings with thickness of 1.6 µm, 2 µm, 2.5 µm, and 3 µm, onto a cemented carbide substrate. Second, the coating-thickness-dependent physical properties were characterized and estimated with a radar chart. Third, the effects of coating thickness on coating antifriction were analyzed with the tool-chip friction coefficient when cutting Inconel 718 with PVD TiAlN coated tools. Both the maximum cutting temperature generated in the chip and the cutting temperature of the tool bodies were measured for analyzation of the thermal barrier effect of coating. Finally, the topographies of the deformed chip and tool-chip contact area were obtained and investigated to determine the effects of coating thickness on the cutting temperature. RESULTS: The tool-chip friction coefficient and coating thermal barrier effect were affected by the coating thickness. Ti(0.55)Al(0.45)N coated tools with moderate coating thickness had fine antifriction effect with Inconel 718. The thermal barrier effect of Ti(0.55)Al(0.45)N coating was positively related to the coating thickness. CONCLUSIONS: The optimal TiAlN coating thickness was determined as 2 μm, which resulted in superior physical properties and reduced the cutting temperature of Inconel 718.