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February 2016

Will Metal 3D Printing Change the World?

You wouldn’t download a car… would you? What if you could print it? The potential game-changing nature of 3D printing is well known, but the process still has its limitations. The vast majority of 3D printers out there – which are getting cheaper all the time – use plastic as their base material. This can cheaply and effectively produce many kinds of objects, ranging through musical instruments, medical models, prosthetics, and even clothing. However, for more hard-wearing applications, forward-thinking creators are increasingly turning to metal 3D-printing. The advantages are obvious: more strength, more durability and a greater range of uses. There is a ways to go before this technology is ready for prime time, but when it is, it might just change the world.

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So Metal

How does it work? In a plastic 3D printer, a digital file is first created containing the design of the object to be printed. This can be constructed from scratch for a completely new object, or by using a 3D scanner to copy an existing object. Depending on the type of printer, material can be melted or softened into thin layers, or a photo-reactive resin can be cured with a UV laser or similar power source one layer at a time. Then, using what is called additive processes, successive layers of material are laid down until the object is created. Each layer is essentially a thinly-sliced cross-section of the actual object.

Metal 3D printers follow the same principle, but of course metals generally (at least those thatmight be most useful for creating solid objects with a 3D printer) have much higher melting points than plastics. Similar to plastics-based systems, one technique is to feed in metal wire that is then melted by a laser using inert gas shielding either surrounding the laser or in a sealed environment. Alternatively, electron beam freeform fabrication uses an electron beam heat source inside a vacuum chamber. However, both of these techniques are expensive and do not lend themselves well to low-cost consumer use.

Opening the Source

However, a group of students from Delft University of Technology has been working on acheaper, open-source solution, available to a wide audience and capable of printing with decent resolution. Essentially, the team has taken a standard MIG (metal/inert gas) welder and attached it to a Prusa i3, a standard plastic 3D printer. The welder uses a continuous feed of wire that is melted as it acts as both a filler metal and an electrode. It’s protected from local contamination by a shielding gas that flows around the melted wire. The wire is fed to the welder at a rate of 400 mm/minute, and is slowly melted and layered. (The method is considerably slower than plastic printing, though, which can reach speeds from 3000 to 18000 mm/minute).The team has so far successfully printed a wall-like structure and several circular shapes, though a great deal more work needs to be done on this project. It could definitely act as a springboard towards more affordable 3D printing, however. Other projects that are aiming for inexpensive 3D fabrication include the MX3D Bridge, which aims to 3D-print a steel bridge; however, the industrial robotic arms used in this printer requires fabrication and regular maintenance by robotics technicians, so this project is not for the general hobbyist.

How to Build a Printer

You can build a metal 3D printer yourself for under $2000 (US) by gathering – or printing – the required materials and following some simple instructions. You might also consider some online technology courses to make sure that you’re up to speed with the requirements. Full instructions are available here, but in brief, here’s what you will need to do:

  • Find or print the required parts
  • Build three pillars to make the frame of the printer
  • Build the platform that the object will be created on
  • Wire up the electronics to control the welder

Ensure that you follow strict safety precautions, because you’re essentially using a modifiedwelder. Use your printer on a flat surface away from water and flammable materials, with proper grounding. Make sure your gas cylinder is secured to an upright support or cart and use appropriate hoses, which should be examined regularly for leaks; reduce clutter in your workspace and ensure proper ventilation. Wear safety glasses and a flame-resistant lab coat at all times, and a welding mask when printing. Don't forget to use pliers or heavy gloves to pick up the substrate after printing. And wear high-top leather shoes, with steel toes if you can!