Experimental investigation of uncoated, single layer, and multilayer-coated TiAlN/TiN tool inserts in dry orthogonal cutting of AISI/SAE 4140 alloy steel

Abstract

Significant temperature rise is stimulated during high-speed machining of metals, specifically in dry cutting conditions. This experimental investigation undertakes the effects of uncoated, single layer coatings (TiN and TiAlN), and multilayer coatings [TiAlN/TiN (9 + 5 µm), (9 + 3 µm), (9 + 1 µm), and (5 + 1 µm)] on cutting tool material during dry orthogonal cutting of AISI/SAE 4140 alloy steel. The study compares crucial parameters such as cutting and feed forces, chip-tool contact area, thickness of deformed chip, chip reduction coefficient, heat partition ratio, flank wear, and shear angle. The layer TiAlN used as the first layer from the Tungsten Carbide (WC) substrate owing to its better adhesion property, whereas TiN used as the second layer (top coating) owing to its better sliding behavior. In this research, cutting operations have carried out using Dean Smith and Grace Lathe machine. A Scanning Electron Microscope (SEM) also used along with a Kistler 9263 dynamometer to measure cutting forces. The cutting temperatures are measured with the help of an infrared, high-resolution thermal imaging camera, ThermaCAM model SC3000 by FLIR. Results have shown that layers act as a thermal barrier that block excessive heat generation in the cutting tool. Thus, this increasing the surface finish, tool life, and overall efficiency, while reducing the abrasive wear, tear, and parallel ridges due to rubbing friction. Furthermore, it has found that multilayer coating of (9 + 5 = 14 µm) shown good consistent results with less variance, specifically in the high-speed machining regions. Hence, the study evidently justifies the usage of coated tool inserts in high-speed dry cutting operations.