ADDITIVE MANUFACTURING is the magazine devoted to industrial applications of 3D printing and digital layering technology. We cover the promise and the challenges of this technology for making functional tooling and end-use production parts.
Issue link: https://am.epubxp.com/i/815448
AM / Sintering Can Wait additivemanufacturing.media 35 process opens up possibilities for what we might consider a vi- able 3D printing process for metal part production. If we accept that additional steps might always be necessary, then maybe a single 3D printing machine does not have to accomplish so much of the work of creating the part. What if a portion of the part-making, even a crucial portion, could be decoupled and moved to a separate device? That question is the key to understanding the new metal 3D printer from MarkForged, says company founder and CEO Greg Mark, because this machine—the Metal X, which begins shipping in September—decouples printing the part from sintering the metal. I recently visited the company's office and manufacturing facility in Cambridge, Massachusetts, to speak with Mark about this machine. With the Metal X, the user employs a separate, stand-alone furnace for the sintering. This change, which is a departure from met- al 3D printing methods such as DMLS, might leave the AM process seeming less elegant—but hold off on that conclusion. The result of the separation of sintering is a step-change reduction in the cost of the machine. Rather than a high- six-figure price tag, the price of this metal additive machine is $100,000, or around $120,000 when the cost of the furnace is included. The ma- chine at present still has significant limitations, most notably related to the limited range of metals it can predictably use. Still, this is a metal 3D printer at a pricing level that a facility such as a small machine shop can likely afford. And that step-change cost reduction does not come with a net increase in the number of steps. True, sintering becomes separate with this machine, and that step is not separate with other additive metal equipment. However, anoth- er feature of this machine, and the development that actually makes the machine possible, is the use of plastic containment—plastic that ultimately vaporizes—as a delivery mechanism for controlling the pre-sintered powder. Thanks to this plastic containment, there is no powder-handling safety concern. Environmental suits are not part of the protocol for this machine. Also thanks to the plastic, there is no build plate. Neither sawing nor EDM are needed for separating parts from a plate just after they leave the machine. Plus, there is no annealing requirement. As the steps related to safety, heat treat and separation are eliminated, the net number of steps in this metal additive process is actual- ly likely to be smaller. Part Behavior MarkForged is the company that launched in 2013 to produce and market the Mark One, a desktop 3D printer generating resilient polymer parts that are given their strength through controlled placement of continuous-strand Kevlar or carbon fiber into the build. Variations on the Mark One machine followed, both higher-end and lower-end versions. The metal 3D printer was announced this year, and though the material on this machine is very different (metal rather than poly- mer composite), this new model is more of a line extension than might initially be recognized. It is an extrusion-deposition machine like the earlier printers (more on the specific mechanism of part creation below), and it uses many of the same components as its predeces- sors. And within MarkForged, this machine draws on much of the same knowledge the company has already developed related to the be- havior of 3D printed parts and how to produce them repeatably. This last point refers to the dynamic nature of a 3D printing process. Parts are in motion as they are grown; they distort as they are printed. The extent to which the MarkForged machines are able to achieve precision sufficient for industrial part production, the aim for all its machines, is partly the Today, the Metal X can be used to produce stainless steel parts without any need for trial and error during sintering, because that trial and error for this type of metal have already been done. The company's team is working out the processing strategies to make various other metals also easy to use with this machine.