Burr formation mechanism and machining parameter effect in slot micro-milling titanium alloy Ti6Al4V

Burr formation is still the major challenge in slot micro-milling of titanium alloy Ti6Al4V due to its difficult-to-machine material properties and hard deburring processing. In the present work, chip and burr formation were investigated by surface morphology observation of slot micro-milling Ti6Al4V, with an emphasis on the top burr and side burr formation mechanism, in which the side burr is defined as the burrs at the bottom edge of the sidewall. Especially, the effect of cutting parameters on burr formation was also analyzed. The results show that the chip shows the segmental in slot micro-milling Ti6Al4V. The up-milling top burr is mainly correlated with the extrusion effect of cutting-edge radius. The extrusion effect of cutting-edge radius, chip turnover induced by micro-milling cutter's helix angle, and chip separation's tearing effect all contribute to the down-milling side top burr formation in micro-milling Ti6Al4V. The up-milling side burrs are general adhesive chips and residual tear burrs due to the falling off of adhesive chips from the tool rake face and plowing-shear-plowing chip removal mechanism of the single cutting pass, respectively. The down-milling side burrs are general residual tear burrs and mental debris due to the transformation of the chip removal mechanism for the single cutting pass and tool deflection from up-milling to down-milling in the micro-milling. The down-milling top width and the side burr width have all shown a decreasing trend with the increase of feed per tooth. It is recommended to adopt the large feed per tooth for minimizing top burr width and side burr width. Our findings can provide a guideline for deburring and suppressing the burr formation in slot micro-milling Ti6Al4V.