Comparison of sustainable cooling/lubrication strategies for drilling of wire arc additively manufactured Inconel 625

Abstract

Machining Inconel presents significant challenges due to the material's high strength, hardness, and heat resistance. These properties often result in accelerated tool wear, modest surface finish, and increased energy consumption during machining processes. Despite its widespread use in industries, the machining of Inconel alloys remains a persistent bottleneck in manufacturing operations. In this study, we focus on drilling rather than milling of Inconel 625, a commonly used nickel-based superalloy, due to its specific relevance in various industrial applications. Drilling operations are critical in numerous contexts, including the fabrication of aerospace components, where precision, hole quality, and efficiency are paramount. Therefore, this study aims to improve machinability of wire arc additively manufactured Inconel 625 by fabricating it with two different travel speeds, 175 mm/min and 185 mm/min as well as by drilling the fabricated Inconel 625 using recently developed sustainable lubrication/cooling strategies, i.e. electrostatic minimum quantity lubrication (EMQL) and cryogenic LCO2. The results show that the sample built with 185 mm/min produces less tool wear, surface roughness, thrust force and power consumption. The use of LCO2 results in approximately 35 % less tool wear, 27 % less surface roughness, 15 % less thrust force, and 4 % lower power consumption compared to EMQL for the sample built at 185 mm/min.