Thermal behavior analysis of coated cutting tool using analytical solutions

Abstract

Nowadays, almost all cutting tools are coated due to improvements in manufacturing processes. The two main reasons are: (1) coatings allow a cut with less friction and less wear resulting in longer tool life and (2) thermal barrier effect, since the contact between workpiece-toolchip occurs in the coating and not in the tool material (substrate). This paper analyzes, the thermal effect of the coating without considering the tribological effect. The thermal behavior with three types of coating: cobalt (Co), titanium nitride (TiN), and aluminum oxide (Al 2 O 3) on a ISO K10 carbide insert of 3 mm thickness was investigated. This paper investigates the behavior of inserts with coatings of thickness of 1, 2, 5, 10, and 20 lm in a onedimensional transient thermal model proposed for a material composed of two layers. A constant heat flux simulates the heat generated in the tool-piece-chip interface for coated and non-coated inserts. The solution of the diffusion equation is obtained using the Green function method. The effect of the coating can then be calculated by analyzing the evolution of the temperature at the cutting interface in contact with the heat flux and the evolution of the temperature at the coating-substrate interface. It can be concluded that coatings have thermal barrier effect, although for coatings of 2 lm thickness, this influence is very small and produces temperature reduction of up to 14%. For thicknesses greater than 5lm, the effect becomes considerable depending on the coating-substrate pair. In the case of TiN carbide, the temperature reduction is 26, 34, and 41% for the thicknesses of 5, 10, and 20 lm, respectively.

Effects of tool coating materials and coating thickness on cutting temperature distribution with coated tools

“…[4][5][6][7] Coating materials with thermal barrier properties have an important influence on the heat transfer process. 8,9 Oliveira et al 10 coated three types of coatings (Co, TiN, Al 2 O 3 ) on the substrate of K10 cemented carbide, applied a constant heat flux to the surface of the cutting tool to simulate the heat generated in the cutting interface, and studied the transient thermal behavior of coated tools with different coating thickness. By analyzing the evolution of the temperature at the cutting interface in contact with the heat flux and the evolution of the temperature at the coating-substrate interface, it is found that the coating has a thermal barrier effect, even coatings with a thickness of 2 μm can produce a temperature reduction of up to 14%.…”

“…Coating materials with thermal barrier properties have an important influence on the heat transfer process 8,9 . Oliveira et al 10 . coated three types of coatings (Co, TiN, Al 2 O 3 ) on the substrate of K10 cemented carbide, applied a constant heat flux to the surface of the cutting tool to simulate the heat generated in the cutting interface, and studied the transient thermal behavior of coated tools with different coating thickness.…”

Modelling and prediction of cutting temperature in the machining of H13 hard steel of multi-layer coated cutting tools

“…It was found that with the increase of coating thickness, the temperature in the tool-chip interface increased with the coating thickness, the temperature in the coated tool body decreased significantly. Oliveira [10] coated the substrate of K10 carbide tool with three different coatings (Co, TiN, Al 2 O 3 ) and loaded a constant heat flow q(t)=25×10 5 W/m 2 on the tool surface (simulating the heat flow density at the tool-chip interface under orthogonal cutting conditions). The experimental temperature on the tool surface of the coated tool is much higher than that of the uncoated tool due to the heating resistance of the coating.…”