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

Metal additive manufacturing is taking more and more space in the industry. From aeronautics to medical applications, these 3D printing technologies are offering brand new opportunities. Here, we are going to talk about Direct Metal Deposition, an additive manufacturing technology using a laser to melt the metallic powder. Unlike most of the other technologies, it is not based on a powder bed but it uses a feed nozzle to drive the powder into the laser beam. It is very similar to Fused Deposition Modeling as the nozzle can move to deposit the fused metal.

Metal 3D printer head

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.

What is Direct Metal Deposition?

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 metallic 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.

Where does this technology come from?

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 an entire object. Then, the substrate is no longer a part to be repaired but a platform to start building.

This metal additive manufacturing technique can also be called Laser Metal Deposition or LMD.

What are the materials used for DMD?

All kinds of metallic materials can be processed by this laser metal deposition 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. It is even possible to use this technology with custom alloys, totally matching your requirements!

What are the particularities of this 3D printing technique?

Among all the laser-based metal 3D printing technologies, DMD is the only one not based on a powder bed. In SLM and DMLS, 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 solidified. There is no powder waste 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 Fused Deposition Modeling (FDM) except that the deposited material can be discontinued, unlike a plastic filament.

What are the advantages?

One of the essential advantages of Laser Metal Deposition is the low heat that is applied during the whole process. Moreover, the high level of control over the laser means that exact amounts of energy can be applied to the highly defined regions of the substrate. This is a reliable manufacturing technique, as you can easily adjust the laser beam, which is also quite stable.

The numerous applications of this technology that we will see later on this page are also part of the various advantages of this metal 3D printing technique.

What are the applications of DMD?

This technology is mainly used in the aeronautics field to repair complex and expensive parts instead of replacing them. That way, the manufacturer saves a spare part and the cost of disassembly and reassembly. This is particularly useful for some expensive components, instead of getting a new expensive metal part, it is now possible to fix it using DMD.  

This laser metal deposition technology can also be used to repair existing parts. Indeed, Direct Metal Deposition is actually the only existing method we know, able to repair, reconfigure or resurface existing parts, molds or dies by adding metal that matches the parent tool. This technique appears to be a great benefit for tooling processes. This singular 3D printing technique is also used for efficient coating and welding.  It is possible to use it to reinforce components locally or to adapt them in terms of geometry

LENS system by Optomec
LENS system by Optomec used to repair a metalic part by Direct Metal Deposition ( Image credit: Optomec)

Have you ever heard about 3D printed bridges? This laser metal deposition technique can also be used at a larger scale, for architectural projects for example. Indeed, 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 entirely built by robots!

Bridge building
This is how it should look like during the bridge building (Image credit: 3D natives).

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 .