Micro milling of WAAM-CMT ER70S-6: Estimating minimum uncut chip thickness interval via surface finish and burr formation

Abstract

Advances in additive manufacturing (AM) have led to a growing demand for increasingly sophisticated post-processing methods. Thus, micro-machining may be required, demanding careful selection of cutting parameters. Therefore, this work contributes new literature on the micro milling of wire arc additive manufacturing (WAAM)-cold metal transfer (CMT) ER70S-6. For this, 400 µm diameter micro tools were used, and eight values of feed per tooth (fz) were evaluated. The results showed that values under 2.5 µm/tooth may not exceed the minimum chip thickness, resulting in increased roughness (Ra = 0.51 µm) and worsened surface texture. The fz of 5.0 µm/tooth is the most suitable to achieve smoother surfaces, resulting in Ra 0.39 µm. The fz of 20.0 µm/tooth was observed to be a good alternative associated with good results, lower burr formation, and high productivity. The results suggest that the minimum uncut chip thickness for WAAM-CMT ER70S-6 lies between 2.5 and 5.0 µm/tooth.