Investigations on burr formation mechanisms in micro milling of high-aspect-ratio titanium alloy ti-6al-4 v structures

•Micro slots with aspect ratio (1.5:1 and 3:1) are fabricated, the burr types and morphology are obtained from experimental results.•Chip scratching and extrusion due to restricted chip removal and residual material owing to size effect contribute to sidewall burr formation.•Burrs on bottom edge of sidewall are generated by chip squeezing and tearing failure owing to size effect in the cutting zone.•The aspect ratio has a positive effect on the top and sidewall burr generation.