Burr Formation and Surface Characteristics in Micro-End Milling of Titanium Alloys

Titanium base alloys are used for aircraft structures, turbine blades and medical implants. The surface of these parts can be functionalized by micro-structuring e.g. to get a more energy efficient turbine or to get a better biocompatibility for medical implants. Micro-end milling with end mills down to 300 mu m is already efficient and reliable for microstructuring ductile materials. We developed and manufactured carbide micro end mills with a smallest diameter of 7 mu m to improve the spectrum of functional structures. This paper describes micro end milling experiments of the difficult to machine titanium alloys Ti-6Al-4V and Ti-6Al-7Nb with 48 mu m micro-end mills. Large areas are machined to observe the micro structure on the surface and the influence on surface quality. The burr formations in slot milling is observed and compared to still existing models. Up milling and down milling at the sidewalls were compared.