Metal 3D Printing
We all have heard about 3D printing, also known as additive manufacturing, but do we really understand how it works? Put simply, 3D printing is a process through which we can make three dimensional solid objects from a digital file.
The 3D printing process turns the digital design of an object into thousands of tiny layers, and then makes the object real, by extruding a material through a 3D printer, recreating these layers from the bottom-up. Each layer is bonded to the next, as the material hardens once it comes out of the printer’s nozzle. These layers can be very complex, meaning 3D printers can create moving parts like hinges and wheels as part of the same object.
3D printing encompasses many forms of technologies and a range of materials as it is being used in almost all industries you could think of, with a myriad of different applications- from consumer goods, to medical products, to architectural structures. In this Designer Spotlight we will be exploring metal as a material for 3D printing and the exciting work of Ahron Wayne.
Ahron Wayne started his professional journey at Lawrence Technological University (LTU) in high-school, working as an intern studying Lipid Droplets. He then went on to receive a Bachelor’s degree in Biochemistry from Michigan State University (MSU). During his fellowship at the Hebrew University in Jerusalem Ahron focused on nematode chemotaxis, and continued onto a master’s degree in Biomedical Engineering from LTU, with a study-abroad semester in Beijing.
Ahron’s master degree research was in scanning 3D microphotography where he developed tools for scanning microscopy aiming to use motors to make cheap microscopes more effective by increasing their field of view. The results of this investigation has been disseminated in Instructables, Hackaday, and Kickstarter, with the ultimate goal being to bring these devices to market.
Ahron has a hands-on, iterative development style that involves 3D modelling, 3D printing, laser cutting, programming, and electronics. He is currently exploring a newer more accessible method of metal 3D printing in the Biomedical Engineering Department at Lawrence Tech in Southfield, Michigan.
The “old style” of metal 3D printing is to use a laser to melt powder into a solid object. It’s an industry standard, but is exceedingly expensive to get started; a typical machine can a million USD. The newer method, however, uses a standard FDM 3D printer, just like those used to make plastic models — greatly reducing the start-up cost.
This FDM metal printing method involves using a 3D printing plastic that is filled with a metal powder. Once the piece has been printed, the next step is to remove the plastic, through a process called debinding. To remove the binder, Ahron places the part in a crucible and then uses thermal decomposition in an oven to break down the plastic — this is a more accessible method than the more common way of using separate chemical equipment. The result is a weak, “brown part”, that is pure metal but extremely porous. Then, the metal is sintered or shrunk in the same oven at a high temperature, creating the strong, solid part. This technique also differs from the industry version by creating a local, protective environment within the crucible itself, using carbon, instead of pumping in an outside source of hydrogen or inert gas — an expensive and dangerous prospect for hobbyists.
It’s similar to the technique of metal injection molding and it brings down the cost of metal printing dramatically. So far the results have been pretty encouraging!
Ahron has been experimenting with materials like Copper, Bronze, 17-4 Steel, and Glass (Pyrex). The company that provides the materials is called The Virtual Foundry, located in Wisconsin. The Virtual Foundry manufactures Filamet™, metal and ceramic 3D printing filaments that work in common 3D printers made for plastics.
All types of Filamet ™ consist of a base metal and a biodegradable and ecological polymer (PLA). This material is free of exposed metal particles and volatile solvents that can be released during printing. These materials are simple to print, since their printing properties are similar to those of the PLA, allowing any user of a 3D FDM printer, to create parts with these filaments, without the need to purchase expensive industrial metal printers. As mentioned earlier, the main limitation is that due to the need to sinter the printed pieces once the PLA is removed, there is usually a trade-off of porosity vs. non-isotropic shrinkage.
Once sintered the piece can be sanded, polished, and welded much the same as wrought metal. With wet sanding it is possible to eliminate the printing lines and other small deformations; Ahron has polished Copper parts before to a mirror-like finish. The Virtual Foundry recommends to start sanding with a grain of 120 (80 for 3M radial disc), being careful not to deform the most delicate areas, such as corners. Once the entire surface has been sanded, a sandpaper of the next grain should be used and so on until it increases 6 or 7 (4 times for the 3M radial disc). Before moving on to the final polishing it is recommended to use a 3000 grit sandpaper, with which a certain gloss is achieved. Finally and once the piece is cleaned with a flannel cloth, the piece can be polished: The Virtual Foundry recommends using a rotating tool with a polishing disc and polishing wax to make polishing faster and more efficient. Simply apply a little polishing wax on the polishing disc and polish with constant movements throughout the piece so as not to generate excess heat, which can deform the piece. In addition to sanding and polishing parts manufactured with Filamet™, unsintered parts can also be carved, melted, welded and smoothed with the application of heat.
Follow Ahron’s investigation on YouTube, where he shares videos of his work.
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