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

Abstract

Micro-scale features with high aspect ratios are used extensively in aerospace parts and biomedical implants. However, burrs produced during the micro-milling process seriously affect surface quality and performance of high aspect ratio structures. In this paper, micro slots with 1.5:1 and 3:1 aspect ratio are fabricated, and burr types and morphology are obtained through experiments. Then burr formation mechanisms were comprehensively investigated from a theoretical and experimental perspective, with the assistance of simulation. The quantitative evaluation of the top burr and sidewall burr dimension is conducted to analyze the effect of aspect ratio on the burr formation in the micro-milling of high-aspect-ratio structures. Moreover, the results suggest that burrs generated during machining can be classified into six categories according to the location: sidewall, entrance, top, exit, the bottom edge of the sidewall, and slot base. And the dimension size of top and sidewall burr is around 30 μm and 40 μm respectively. The burr formation process in high aspect ratio structures has a significant relationship with the limitation of the sidewall, tearing failure, and extrusion of chip materials. Furthermore, the aspect ratio has a positive effect on the top and sidewall burr generation. The adoption of sharper cutting edge can obtain a reduction of the top and sidewall burr dimension.