Internally cooled tools as an innovative solution for sustainable machining: Temperature investigation using Inconel 718 superalloy

Abstract

Machining is a process that involves intense heat generation at localized points within the tool-chip interface. This leads to elevated temperatures, which can be detrimental to cutting tools. This issue becomes even more crucial when dealing with superalloys like Inconel 718, as they exhibit high shear strength and good creep resistance. Consequently, a significant amount of energy is expended, increasing the cutting temperature. Until now, the primary technique employed to address this issue has been using Cutting Fluids (CFs). In machining, a portion of costs is attributed to fluid handling. It also contains harmful elements that can pose health risks, potentially leading to conditions such as cancer. Moreover, the toxic components can contribute to environmental degradation when improperly disposed of. Therefore, this study proposes an innovative cooling technique called Internally Cooled Tools (ICTs). The ICTs employ an internally circulating coolant fluid through closed cooling channels within the cutting tools, eliminating fluid dispersion into the atmosphere. The main objective was to compare the performance of ICTs in controlling the tool-chip interface temperature during Inconel 718 turning using hard metal tools. For this purpose, a complete factorial experimental design (2⁵) was utilized, with the response variable being the temperature measured by the tool-work thermocouples technique. Beyond that, a sustainable assessment was performed using the Pugh Matrix method. Many key sustainable factors were evaluated related to three atmospheres, cutting fluids in abundance – CFA, dry machining, and ICT. The data base used was a depth literature investigation together with results found in this work. The main findings of this entire work demonstrated that an increase in cutting parameters corresponded to an increase in temperature, as anticipated. TiNAl coating reduced the temperature by up to 10% compared to uncoated tools. Similarly, applying ICTs led to temperature reductions of up to 17% compared to dry machining conditions. The Pugh Matrix made considering 12 factors showed that ICT (14 points) was the most sustainable lubri-cooling method in comparison to CFA (3) and DM (5). Ultimately, ICTs showed to be a promising eco-friendly method. It outperformed conventional methods, showcasing a remarkable heat dissipation capacity. As a result, further studies are warranted to delve deeper into this promising approach.