Micro-machinability of nanoparticle-reinforced Mg-based MMCs: an experimental investigation

As a composite material with combination of low weight and high engineering strength, metal matrix composites (MMCs) have been utilised in numerous applications such as aerospace, automobile, and bioengineering. However, MMCs are recognised as difficult-to-cut materials due to their improved strength and high hardness of the reinforcing particles. This paper presents an experimental investigation on micro-machinability of Mg-based MMCs reinforced with Ti and TiB2 nano-sized particles. The tool wear of AlTiN-coated micro-end mills was investigated. Both abrasive and chip adhesion effect were observed on the main cutting edges, whilst the reinforcement materials and volume fraction play an important role in determining the wear type and severity. The influence of cutting parameters on the surface morphology and cutting force was studied. According to analysis of variance (ANOVA), depth of cut and spindle speed have significant effect on the surface roughness. The specific cutting energy, surface morphology and the minimum chip thickness was obtained and characterised with the aim of examining the size effect. Furthermore, higher cutting force and worse machined surface quality were obtained at the small feed per tooth ranging from 0.15 to 0.5 mu m/tooth indicating a strong size effect. Overall, Mg/TiB2 MMCs exhibit better machinability.