Electropolishing-enhanced, high-precision 3D printing of metallic pentamode metamaterials

Abstract

Additive 3D printing has been one of the most powerful and effective techniques to realize 3D intricate structures. However, its limitations including a high threshold for high-precision preparation and poor surface roughness in metalworking impede further development, such as metallic pentamode metamaterials (PMs) due to the special structural regimes and extremely strict size requirement at the intersection nodes. Herein, a novel electropolishing-enhanced 3D printing method is proposed to fabricate high-precision metallic PMs with improved precision and surface smoothness. Experimental results evince that this hybrid additive-subtractive method can fabricate PMs with much smaller critical size and smoother surface, which cannot be achieved by the same-level 3D printing methods. The minimum processable size can reach ∼ 100 μm that greatly breaks through the limitation of initial additive manufacturing (EOS M280 SLM, ∼ 200 ± 50 μm). A ∼ 100 μm intersection can support 107 times its own weight. Moreover, the D/d of elementary biconical rods can be refined from an initial 6 to an astounding 52, which is beyond the scope of conventional 3D printing. This proposed hybrid additive-subtractive method, namely electropolishing-enhanced 3D printing, breaks the limits of conventional 3D printing by significantly improving the precision and shows great potential in low-cost but high-precision manufacturing.