Dissolvable Metal Supports for 3D Printing

Support for a visiting professor plus an off-the-cuff remark have led an Arizona State University (ASU) researcher to develop what could be the Holy Grail solution to speeding up the end-to-end process of metal 3D printing.

Owen Hildreth, ASU assistant professor of 3D Nanofabrication, was developing new approaches to reactive silver ink production when he thought he’d sit in on talks regarding the soon-to-be-opened ASU Polytechnic Manufacturing Research and Innovation Hub. One of the speakers, Timothy Simpson, was describing the practical challenges of setting up an additive manufacturing (AM) lab.

Combining a mechanical engineering degree (applied to five years’ work in the 2D printing industry) with a Ph.D. in nanofabrication materials engineering, Hildreth just may have been in the perfect position to bring a fresh perspective to the metal support problem. In contrast to the use of mechanical tools such as wire-EDM equipment, his concept would cause certain areas of a metal AM part to react chemically when immersed in a corrosive solution. The goal was to produce controlled degradation that would literally eat away the supports but leave the actual part virtually intact.

However, because multi-material 3D printing systems are not yet widely available, Hildreth also investigated ways to selectively remove the supports of powder-bed-type metal AM parts. Starting with a simple design for demonstration — a small 17-4 stainless steel cylinder 3D-printed with a single row of 100-micron-diameter needle-like supports — he tested two possible approaches.

In the first one, termed direct dissolution, the part was heat-treated (annealed) while packed with sodium ferrocyanide; this step precipitated out much of the protective chromium carbide, rendering the no-longer-stainless steel susceptible to chemical etching. The latter process was successful, but the part itself experienced significant etching, which continued the longer the part was allowed to sit in the solution.

Source: http://www.rapidreadytech.com/