Estudo da temperatura na interface ferramenta-cavaco no torneamento do Inconel 718 com ferramentas refrigeradas internamente

Abstract

Machining is a process that involves high heat generation in localized points in small areas at the tool-chip interface. This leads to high temperatures that are detrimental, especially to cutting tools. This problem is even more critical for superalloys such as Inconel 718, as they exhibit high shear strength and good creep resistance, resulting in high energy expenditure and elevated cutting temperatures. Until now, the main technique used to overcome this problem consists of using abundant cutting fluids (FCAs). This technique has been the industry standard since at least the 19th century. However, its use poses sustainability issues - economic, social, and environmental. A significant portion of machining costs is attributed to the handling of cutting fluids, which also contain harmful elements that can pose health risks, including cancer, as well as toxic substances that degrade the environment if improperly disposed. Therefore, this study proposes a new cooling technique called Internally Cooled Tools (ICTs). ICTs utilize a coolant flowing internally through the cutting tools via closed-loop cooling channels, without any fluid dispersion into the atmosphere. The main objective was to compare the performance of ICTs in terms of the temperature at the tool-chip interface during the turning of Inconel 718 using carbide tools. To achieve this, a complete factorial experimental design (2^5) was used, with the response variable being the temperature measured by the tool-workpiece thermocouple method. The input variables were cutting speed (Vc = 33 m/min and 67 m/min), feed rate (f = 0.103 mm/rev and 0.297 mm/rev), depth of cut (Ap = 0.2 mm and 0.4 mm), coating (uncoated or TiNAl-coated), and atmosphere (ICTs and Dry). The main results showed that with increasing cutting parameters, the temperature also increased, as expected. The use of TiNAl coating reduced the temperature by up to 10 % compared to the uncoated tool. Similarly, the use of ICTs reduced the temperature by up to 16 % compared to the dry condition. Finally, ICTs outperformed conventional techniques, demonstrating a high heat removal capacity. Further studies are deemed necessary.