Direct Metal Deposition (DMD) Fabrication Process for Metal 3D Prints

The Direct Metal Deposition is an additive manufacturing technology using a laser to melt metallic powder. Unlike most of the other technologies, it is not based on a powder bed but it uses a feed nozzle to propulse the powder into the laser beam. It is very similar to Fused Deposition Modeling as the nozzle can move to deposit the fused metal.

In Direct Metal Deposition, the laser beam and the powder spray are focused and scan the substrate to deposit the metal. BeAM is one of the main DMD machine manufacturer.

Principle

As most of the metal 3D printing technologies ( selective laser melting, direct metal laser sintering ), this technology is based on the transformation of powdered metal into a solid metalic object. The main principle is to use a powder feed nozzle than propulse the powdered metal into the laser beam. The powdered metal is then fused by the laser. Using a layer by layer strategy, the printer head , composed of the laser beam and the feed nozzle, can scan the substrate to deposit successive layers. The deposit width is between 0.6 to 2.4 mm while the layer thickness lies between 0.2 and 0.8 mm.

Materials

All kinds of metallic materials can be processed by this technology. Among the most common are steel and aluminum. But very technical materials are also available such as Nickel based alloys, Titanium, Cobalt and Copper.

Particularities

Among the laser based metal 3D printing technologies, DMD is the only one not based on a powder bed. In SLM andDMLS , the unfused metallic powder is used as support material and can be reused. In DMD, supports can be required to maintain the building object but almost all the powder is transformed into solid. There is no waste powder to recycle. This technology also has the ability to comply with a freeform substrate, a planar building platform is not compulsory.

It can be compared with FDM (renvoi vers la fiche de cette techno → absente) except that the deposited material can be discontinue, unlike a plastic filament .

History

In the first place, Direct Metal Deposition was called Laser Cladding as it can be used to add a certain amount of metal in order to repair a damaged part. With the expansion of 3D printing technologies to create near end-use parts, this technology is then also used as a way to create from the ground an entire object. Then, the substrate is no longer a part to be repaired but a platform to start building.

Applications

This technology is mainly used in the aeronautic field to repair complex and expensive parts instead of replacing them. That way, the manufacturer saves a spare part and the cost of dissambly and reassembly.

Recently, MX3D , a Dutch team, used this technology to build a metallic bridge. The particularity of the project is that the 3D printers were specifically conceived to move into the building bridge. It is the first bridge entriely build by robots!

One of the first firm to propose this technology is Optomec which patented their LENS system. Other main actors in this field are Trumpf and the French company BeAM.

Direct Metal Deposition is mainly used in aeronautics which is one the main industrial field very active in additive manufacturing, to know more about the 4 areas where 3D printing is unstoppable, download our ebook .