Wear Behavior Phenomena of TiN/TiAlN HiPIMS PVD-Coated Tools on Milling Inconel 718

Abstract

Due to Inconel 718’s high mechanical properties, even at higher temperatures, tendency to work-harden, and low thermal conductivity, this alloy is considered hard to machine. The machining of this alloy causes high amounts of tool wear, leading to its premature failure. There seems to be a gap in the literature, particularly regarding milling and finishing operations applied to Inconel 718 parts. In the present study, the wear behavior of multilayered PVD HiPIMS (High-power impulse magnetron sputtering)-coated TiN/TiAlN end-mills used for finishing operations on Inconel 718 is evaluated, aiming to establish/expand the understanding of the wear behavior of coated tools when machining these alloys. Different machining parameters, such as cutting speed, cutting length, and feed per tooth, are tested, evaluating the influence of these parameters’ variations on tool wear. The sustained wear was evaluated using SEM (Scanning electron microscope) analysis, characterizing the tools’ wear and identifying the predominant wear mechanisms. The machined surface was also evaluated after each machining test, establishing a relationship between the tools’ wear and production quality. It was noticed that the feed rate parameter exerted the most influence on the tools’ production quality, while the cutting speed mostly impacted the tools’ wear. The main wear mechanisms identified were abrasion, material adhesion, cratering, and adhesive wear. The findings of this study might prove useful for future research conducted on this topic, either optimization studies or studies on the simulation of the milling of Inconel alloys, such as the one presented here.

INCONEL® Alloy Machining and Tool Wear Finite Element Analysis Assessment: An Extended Review

“…Sousa et al [67] scrutinised recent advancements in TiAlN-based coatings, including nanolayered, nanocomposite, and Ru-, Mo-, and Ta-doped coatings, evaluating their mechanical properties and comparing their cutting behaviours during turning and milling processes. Later on, Sousa et al [68] experimentally investigated the wear characteristics of multilayered TiN/TiAlN-coated end mills through Physical Vapour Deposition (PVD) [69] and High-Power Impulse Magnetron Sputtering (HiPIMS). These tools were employed in finishing operations on INCONEL ® 718 to advance the comprehension of the wear patterns exhibited by coated tools during the machining of these alloys.…”

Investigations on the Surface Integrity and Wear Mechanisms of TiAlYN-Coated Tools in Inconel 718 Milling Operations

“…Even with coatings, the wear generated in the machining process is still a topic that should be further explored. Much information can be taken from models and simulations that can predict wear behaviour [55], as well as the quality of the machined surface, quickly and economically [56]. However, these models are complex and depend on prior knowledge, in addition to being little explored in milling, especially for materials that are difficult to machine, such as Inconel 718.…”

An In-Depth Exploration of Unconventional Machining Techniques for INCONEL® Alloys

“…The commercial WC TiAlN-coated tool [ 32 , 33 ] used in the experiments suffered mainly from erosion on the cutting edge due to diffusion wear after the abrasive wear when cutting INCONEL ® 713C. This type of coating, TiAlN, and its variants TiN [ 34 ], TiAlYN [ 35 ] and TiAlVN, have been experimented with in INCONEL ® 718. Osmond et al [ 36 ] described the mechanisms involved in chip formation and wear for SiAlON-based ceramics and silicon carbide whisker-reinforced alumina (WRA, Figure 4 ) round inserts during the turning process of solution-annealed INCONEL ® 718, utilizing a cutting fluid with an oil-concentration of 10%.…”