Sep 11, 2017 | By David

Manufacturers using 3D printing technology to produce metal parts tend to use one of two methods: SLS (selective laser sintering) or SLM (selective laser melting). Each of these techniques has its particular advantages, but the relatively high costs involved as well as the emission of potentially harmful substances are drawbacks common to them both. A new metal 3D printing method has now been developed by an Austrian company that could present a significantly cheaper and safer alternative. Known as FMP (filament metal printing), the process was recently launched at the headquarters of EVO-tech.

Filament metal printing is close to laser sintering in that it makes use of a volume of metal powder that is selectively melted before re-solidifying into the desired shape. EVO-tech’s innovation is to first process this metal powder to form a filament, similar to the plastic filaments used in FDM or FFF 3D printing. Metal filaments for extrusion methods have been available before, but unlike with these, EVO-tech's technique is capable of producing parts as close to metallic as anything made with metal powder.

After the metal powder is chosen for the filament, a suitable binding material, usually a polymer of some kind, is mixed with it. The resulting granular feedstock can then be formed into a filament. This metal filament can be extruded through a nozzle, at pressure and a high temperature. So far this step has been achieved using EVO-tech’s own EVO-lizer 3D printer, which is specially designed for the process with a hardened, high temperature nozzle (up to 330 degrees Celsius) and a high temperature print bed.

The part that is produced by the extrusion process is known as the ‘green part’. Once this is completed, the next stage is to remove most of the binding material. There are various de-bindering methods possible, such as thermal debindering, cathalytic debindering or use of solvent de-binders. The resulting ‘brown part’ will now be very brittle, consisting almost entirely of metal powder that is loosely held together by whatever residual polymer remains.The final step is sintering, which removes the remaining polymer binding agent and shrinks the ‘brown part’ to form a stronger, firmer final product. Temperatures up to 1300 degrees Celsius are necessary, to burn off the plastic residue, shrinking the part by up to 20 percent.

The final product left behind is a precision-manufactured, high-quality object with excellent material properties. A similar process to FMP, known as powder injection molding, has been used for many years. This also makes use of highly sensitive plastic binding materials and a final sintering phase to produce metal parts.

A major advantage of FMP is that it makes it possible to 3D print metal parts with cavities. Cooling channels or honeycomb structures for more lightweight construction are now much easier to produce using 3D printing methods. The lack of a metal powder bed means that the process doesn’t emit harmful substances, so a FMP 3D printer can be installed in a regular work environment like an office.

This technique took EVO-tech around a year and a half to master, and was developed with the support of German chemicals giant BASF, whose influence on the 3D printing world is growing at a considerable rate. The technology is available for 90 percent cheaper than other metal 3D printing methods. This will make the production of 3D printed metal parts much more accessible to a wide range of manufacturers, in different industries for all kinds of varied applications.

 

 

Posted in 3D Printing Technology

 

 

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orest wrote at 9/15/2017 4:06:50 PM:

If it shrinks by 20%, can it still be "precision-manufactured" ? I very much doubt that - at least it deserves a comment. Similar solution has thevirtualfoundry.com. For copper filament they claim 91.5% copper content, i.e. the shrincage should be below 10%. I backed them on kickstarter and as well got spool of metal filament, though did not try yet (don't have an access to a kiln).

NikNYC wrote at 9/13/2017 5:30:58 PM:

Show the required sintering oven, eh?

Lornezo wrote at 9/11/2017 12:33:02 PM:

So basically it's the same system as the Desktop Metal Studio and the Markforged Metal X systems...



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