Tool wear mechanisms in cold plasma and nano-lubricant multi-energy field coupled micro-milling of Al-Li alloy

Abstract

Al-Li alloy has excellent overall performance and great development potential, which has been considered as a very ideal structural material for aerospace applications. However, the high ductility causes material adhesion to the tool surface, giving rise to severe tool wear, tool breakage, and other machining problems, which restrict the machining quality and practical application of Al-Li alloy structural parts. The multi-filed coupling of cold plasma and nano-lubricant minimum quantity lubrication (CPNMQL) may provide new enlightenment to break this bottleneck. Effects of the multi-field on the micro-milling process were characterized by tool wear, micro-milling force, three-dimensional surface roughness (Sa), and micromorphology. The research results demonstrated that cold plasma (CP) could not only increase the permeability of nano-lubricant on the Al-Li alloy surface but also enhance the material removal efficiency. When the micro-milling distance was 2 m, the average VB value (3.7 µm) of the three tool teeth under CPNMQL condition was reduced by 80.7 %, 54.9 %, and 51.3 %, while micro-milling edge radius (4.4 µm) decreased by 73.2 %, 24.1 %, and 44.3 % compared to dry, nano-lubricant minimum quantity lubrication (NMQL), and CP conditions, respectively.