Abstract
In the current study, the potential of dry machining of the titanium alloy Ti-6Al-4V with uncoated tungsten carbide solid endmills was explored. It is demonstrated that tribo-oxidation is the dominant wear mechanism, which can be suppressed by milling in an extreme high vacuum adequate (XHV) environment. The latter was realized by using a silane-doped argon atmosphere. In the XHV environment, titanium adhesion on the tool was substantially less pronounced as compared to reference machining experiments conducted in air. This goes hand in hand with lower cutting forces in the XHV environment and corresponding changes in chip formation. The underlying mechanisms and the ramifications with respect to application of this approach to dry machining of other metals are discussed.
Highlights
Titanium-based alloys are widely used for demanding applications in transportation and energy conversion industries
Figure seems to demonstrate that wear of the tool is much more pronounced in presence oxygen
The scanning electron microscopy (SEM) analysis of the tools clearly reveals that adhesions on rake face and flank face are SEM analysisofofthe thetools toolsclearly clearly reveals reveals that that adhesions on and face areare adhesions onrake rakeface face(Figure andflank flank face substantially lessanalysis pronounced upon milling ininan
Summary
Titanium-based alloys are widely used for demanding applications in transportation and energy conversion industries. The most frequently used alloy in this field is Ti-6Al-4V This material combines excellent corrosion resistance with high strength and low density [1]. For machining of titanium-based alloys in a cutting speed range between 60 and 120 m min−1 , cemented tungsten carbide tools with physical vapor deposition (PVD) coatings are the state of the art and widely used [3]. Milling of titanium alloys is challenging as the material has low heat conductivity, low elastic modulus, and high chemical reactivity resulting in a strong tendency to build adhesions on the cutting material [4]. Given the low heat conductivity, the use of lubricants is crucial to cool the cutting tool and avoid degradation of the near-surface layer of the workpiece [6]. Hartung et al suggested that a Metals 2020, 10, 1161; doi:10.3390/met10091161 www.mdpi.com/journal/metals
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