High-resolution metal 3D printing via digital light processing

Three-dimensional (3D) printing of complex metallic parts with a micrometer resolution can extend the application of additive manufacturing to various fields wherein the mechanical, thermal, and electrical properties of metals are essential. Digital light processing (DLP) offers high-resolution and scalable 3D printing via vat photopolymerization (VPP). We present a high-precision metal 3D printing method, namely lithography metal additive manufacturing (LMAM) that uses DLP for a photosensitive resin filled with metal powder. The printing process and sintering conditions for a stainless-steel feedstock are discussed. Highly complex and hollow structures with a spatial resolution of 35 μm and surface roughness as low as 1 < Ra < 2 μm can be printed on a decimeter scale without any support structures. The density and tensile strength of the sintered parts are 99.3 % and 93 %, respectively, of those of annealed 316 L steel. The LMAM method is suitable for manufacturing small and highly accurate devices with tailored designs in diverse areas, such as microheat exchangers, biomedical implants, and metamaterials, as well as extends metal 3D printing to chemical engineering for pharmaceutical applications.