An evaluation of heat partition in the high-speed turning of AISI/SAE 4140 steel with uncoated and TiN-coated tools

Abstract

In manufacturing by machining, thermal loads on cutting tools can have a major influence on tool wear and hence process cost, especially at higher cutting speeds. An investigation has been undertaken to determine heat partition into the cutting tool for high-speed machining of AISI/SAE 4140 high-strength alloy steel with uncoated and TiN-coated tools. The cutting tests have been performed at cutting speeds ranging between 100 and 880 m/min with a feed rate of 0.1 mm/rev and a constant depth of cut of 2.5 mm. Cutting temperatures are measured experimentally using an infrared thermal imaging camera. The sticking and sliding regions are investigated from an examination of the tool-chip contact region using a scanning electron microscope (SEM). In addition, non-uniform heat intensity is modelled according to the contact phenomena. In this work, evaluation of the fraction of heat flowing into the cutting tool is carried out by iteratively reducing the available heat flux until the finite element method (FEM) temperatures are simultaneously matched at multiple points with the experimentally measured temperatures. This paper elucidates on the differences in thermal shielding for uncoated and TiN-coated tools. It is found that heat partition into the cutting tool decreases from a fraction of 0.41 to 0.17 for conventional cutting speeds and increases from 0.19 to 0.24 for high-speed machining when using uncoated carbide cutting tools. On the other hand, with TiN-coated tools, heat partition varies from 0.35 down to 0.095 for the whole range of cutting speeds. These results clearly show that the use of TiN-coated tools generally reduces heat partition into the cutting tool, but does so more significantly in high-speed machining (HSM) as compared with conventional machining speeds. The driver behind this study on heat partition in machining with TiN coatings is the design of coatings with enhanced thermal shielding properties.

The Influence of High-speed Milling Strategies on 3D Surface Roughness Parameters

“…High-speed machining can be defined as machining at considerably higher cutting speeds and feed rates compared to those in traditional methods. HSM processes enable high material removal rates, low cutting forces, reduced lead times and improved part precision [6]. The distinction between conventional and high-speed machining is based on the workpiece material being machined, type of cutting operation, and the cutting tool used [7].…”

Influences of TiAlN Coating on Cutting Temperature during Orthogonal Machining H13 Hardened Steel

“…The tool-chip contact length influences the friction of tool-chip contact interface. Notable investigations on the tool-chip contact length in metal machining have been performed over the last five decades such as those by Friedman [22], Balaji [13,23], Mativenga and Sheikh [15,[24][25][26][27] and Grzesik [14]. Mativenga et al [25] pointed out that cutting tool and workpiece material, cutting parameters and cutting operation type affected tool-chip contact length.…”

Heat partition effect on cutting tool morphology in orthogonal metal cutting using finite element method

“…Akbar et al [2] conducted a number of experiments to find the variety of cutting forces in orthogonal machining by using uncoated and coated cutting tools. There is a decrease in cutting forces between the cutting speeds of 100 m/min and 395 m/min, a slight increase in cutting forces between the cutting speeds of 395 m/min and 565 m/min, and finally a fall in cutting forces in the HSM region for TiN-coated tools.…”