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A Comprehensive List of Metal 3D Printing Technologies

Metal additive manufacturing
Above: Arc Series of Metal 3D Printers/Image Source: Gefertec

In continuation to the series on metal 3D printing, in this post we bring you a comprehensive list of all metal 3D printing technologies that are currently available on the market. The list covers the popular metal additive technology types currently used by a range of industries.

As many of you must already be knowing that Metal 3D printing, also known as Metal Additive Manufacturing, is rapidly gaining acceptance across industries. End users are now investing in metal 3D printing systems and incorporating them into their manufacturing workflow, thanks to an ever-expanding material library.

Metal 3D printing was once thought to be too expensive for small and medium-sized businesses to purchase, but as prices have dropped and new application-specific metal materials have been developed, metal 3D printing is becoming more popular around the world.

Important Metal AM Technology Terms

Before we dive into the metal 3D printing technologies, it is important to understand the following terms.

Sintering: Sintering means heating the material (or particles) to the point of liquefaction but not completely melting them. The sintering temperature is always less than the melting temperature.

Green State: A state of the metal 3D printed part where the metal particles are held together by the use of binder/binders material.

Debinding:This is the process of removing the binder material from the green part.

Furnace Sintering:This step follows the debinding process. In the furnace, the metal 3D printed part is sintered which fuses the metal parts to form highly dense solid parts.

Metal 3D Printing Technologies

We explore multiple metal 3D printing technologies that are popularly used across industries. Check out our list below:

1. Bound Metal Deposition™ (BMD) – Metal Additive Manufacturing Technology
2. Direct Metal Laser Sintering (DMLS) & Direct Metal Laser Melting (DMLM)
3. Selective Laser Melting (SLM) & Electron Beam Melting (EBM)
4. HP’s MetalJet Fusion – Metal Additive Manufacturing Technology
5. Directed Energy Deposition (DED) Metal Additive Manufacturing Technology
6. Ultrasonic Additive Manufacturing (UAM) – Metal Additive Manufacturing Technology
7. MELD – Metal Additive Manufacturing Technology
8. Wire Arc Additive Manufacturing (WAAM)
9. Cold Spray Additive Manufacturing – Metal Additive Manufacturing Technology
10. Joule Printing™ – Multi-Metal 3D Printing Technology
11. Water-based Metal Additive Manufacturing Technology
12. Cold Metal Fusion Technology
13. Atomic Diffusion Additive Manufacturing (ADAM)


1. Bound Metal Deposition™ (BMD) – Metal Additive Manufacturing Technology

Metal Additive Manufacturing
Above: Bound Metal Deposition™ (BMD) technology/Image Credit: Desktop Metal

Bound Metal Deposition™ (BMD) is an extrusion-based metal AM technology developed by Desktop Metal. While prevalent methods used metal in form of a powder or wire feedstock, BMD 3D printing technology uses bound metal powder rods held together by wax and a polymer binder. These rods are used as feedstock in Desktop Metal systems.

The 3D printing process is similar to a material extrusion 3D printer where the metal rods are heated and extruded onto the build platform according to the geometry of the part in a layer-by-layer form.

The 3D printed object thus created, is still in a green state and so it is then debinded followed by a sintering stage to get the final full-metal part.

2. Direct Metal Laser Sintering (DMLS) & Direct Metal Laser Melting (DMLM)

Metal Additive Manufacturing
Above: EOS M 300-4 system/Image Credit: EOS

Direct Metal Laser Sintering (DMLS) is one of the most popular metal 3D printing technologies. It is one of the earliest metal AM technology to be invented and so it is widely used in various industries. DMLS also offers a comparatively large material range than a few other processes.

This technology uses powdered metal materials to create objects. It used powerful CO2 lasers that are flashed onto the fine metal powder particles. As the laser traces the geometry of the object to be formed, the particles in the line of the laser fuse together with their adjacent particles thus forming a bond. This process of laser tracing the geometry continues for the entire layer until all points are covered. After the first layer is printed, the build plate moved down and the second layer is printed on top of the first layer and this process continues till all the layers are 3D printed.

An alternative to DMLS is DMLM (Direct Metal Laser Melting). The only significant difference is in the heating temperatures. In DMLS the powder particles are sintered whereas in DMLM the particles are melted.

3. Selective Laser Melting (SLM) & Electron Beam Melting (EBM)

3D Printed Surgical Implants
Above: SLM Solutions SLM800 metal 3D printer/Image Credit: SLM Solutions

Both, Selective Laser Melting (SLM) & Electron Beam Melting (EBM) are similar types of powder bed fusion metal 3D printing technologies and so they are quite similar to DMLS technology with a few significant differences.

SLM metal AM technology also uses a powdered metal material with lasers to fuse the adjacent particles. The difference between SLM and DMLS is in the heat. In SLM, the particles are melted rather than sintering (like in the case of DMLS).

Since metals are melted, the SLM technology is a very high-energy process. The melting can also lead to stresses inside the final product. But the SLM prints objects that are denser and stronger than DMLS.

SLM technology prints with materials like stainless steel, tool steel, titanium, cobalt chrome, aluminium, nickel alloys, etc.

In the case of EBM, only the heat source changes. Instead of a laser, an electron beam is used to melt the particles to fuse them. EBM can only be used with a very limited number of materials.

4. HP’s MetalJet Fusion – Metal Additive Manufacturing Technology

Metal 3D printing
Above: HP’s Metal Jet 3D Printing Technology/Image Credit: HP, Inc.

HP’s revolutionary 3D printing technology called Multijet Fusion has been a game-changer. It has brought a new level of voxel-level control on 3D printing. HP has two technologies working on similar principles – Multi Jet Fusion and Metal Jet Fusion. The only difference being in the use of materials. The Multi Jet Fusion technology makes use of polymers while Metal Jet is for metals. The working remains the same.

The Metal Jet technology uses powdered metal materials like stainless steels (17-4 PH and 316L) with applications in automotive, medical, industrial, and 3Cs (computers, cellphones, and consumer electronics).

5. Directed Energy Deposition (DED) Metal Additive Manufacturing Technology

LENS 3D Printing Systems by Optomec
Above: LENS 3D printing process/Image Credit: Optomec

Directed Energy Deposition (DED) is a metal AM technology that uses metal in a powdered or a wire form as the feedstock material. This material is pushed into the nozzle where it is heated by employing a laser (Laser Energy Net Shape – LENS) or electron beam (Electron Beam Additive Manufacturing – EBAM) and successively deposited onto the build platform. The entire process takes place under an inert atmosphere to protect the material from unwarranted oxidation.

DED has multiple variants like Laser Engineered Net Shaping (using a laser), Electron Beam Additive Manufacturing (using electron beam), Rapid Plasma Deposition (using plasma arc), and Wire Arc Additive Manufacturing (using electric arc) each with its own set of advantages.

6. Wire Arc Additive Manufacturing (WAAM)

3DMP Technology
Above: WAAM technology in operation/Image Credit: Gefertec

Wire Arc Additive Manufacturing (WAAM) is a unique metal 3D printing technology, that shows huge potential for large-scale 3D printing applications across a wide range of industries.

It is a variation of the Direct Energy Deposition 3D printing technology but uses an arc welding process to melt metal wire. Unlike other metal AM processes, WAAM uses an electric arc as the heat source.

The melted wire is extruded in the form of small beads or liquid metal. Adjacent beads fuse together to form a layer of metal. This process is repeated for the entire layer and for all the subsequent layers till the entire object is 3D printed.

The WAAM technology is popularised by many companies like MX3D, WAAM3D, ALM3D, LEAS, Gefertec, etc. for various large-scale applications.

7. Ultrasonic Additive Manufacturing (UAM) – Metal Additive Manufacturing Technology

Above: Metal 3D printing with Sonic Layer 7200/Video Credit: Fabrisonic/YouTube

The Ultrasonic Additive Manufacturing (UAM) falls under the Sheet Lamination category of 3D printing technology.

In this metal 3D printing technology, metal sheets are bound together using ultrasonic welding. Since the technology does not involve any melting, the products formed by this technology maintain their density as well as strength. After the welding, the part does not require any additional step of machining or removal of material.

In UAM technology different metals like aluminium, copper, stainless steel, and titanium can be joined together which allows for greater flexibility in the strength requirement of the part.

8. MELD – Metal Additive Manufacturing Technology

MELD Metal Additive Manufacturing Machine
Above: B8 Model MELD Machine/Image Credit: MELD Manufacturing

The MELD 3D printing technology, patented by Aeroprobe Corporation and now held by Meld Manufacturing, is a unique solid-state metal additive manufacturing process where the metal is not sintered or melted.

This technology is much more than just a metal additive manufacturing technology. It can offer component repairs, metal joining, custom metal alloy and metal matrix composite billet, and part fabrication and coating applications.

In MELD 3D printing, the metal is heated through a combination of high force and friction right up to the point where the heated metal just starts to flow freely. The free-flowing metal is then ‘MELDed’ together. The MELD metal behaves like a thick viscous liquid. But it isn’t a liquid. In this special plastic state, the metal is still solid. That is what makes MELD unique.

MELD is the first process to give you the power to build 3D parts in a solid-state. No melting means you can make products that rival or beat parts made with traditional subtractive machining, all in one step.

9. Cold Spray Additive Manufacturing – Metal Additive Technology

Metal AM Technology
Above: Cold Spray Additive Manufacturing process/Image Credit: Science Direct

The Cold Spray Additive Manufacturing process involves accelerating powdered metal particles with a supersonic gas jet and firing them at a substrate layer. The substrate layer can be either a build platform where the printing starts from scratch or an existing component where the material is deposited to either build a new part or repair the existing component.

The technology is called as Cold Spray because it does involve melting or even heating of the material. The material is simply blasted at supersonic speeds and this high velocity causes the powder material to plasticise on impact forming a solid-state bond with the substrate.

The process is controlled with the help of an industrial robot that performs precise movements to create complex shapes. In comparison to the traditional processes, the cold spray technology is faster.

The cold spray AM method can be effectively used for making repairs and modifications to components.

10. Joule Printing™ – Multi-Metal 3D Printing Technology

Multi-Metal AM Technology
Above: Joule Printing™ in operation/Image Credit: Digital Alloy

Joule Printing™ is a multi-material metal additive technology developed by Digital Alloys, a Massachusetts-based manufacturer. It uses a metal wire as its base material rather than the expensive powders used in comparative systems. It works with any metal in wire form. The technology is a radically simple, high-speed process for melting wire into useful shapes.

The basic working process of Joule Printing™ is as follows:

  1. The process starts with rapid, precise motion as the wire feed systems position the tip of the wire in contact with the desired printing (melting) location.
  2. Once the wire is positioned, the system runs a current through the wire. This melts the wire tip using joule heating (aka “resistance heating”), the same physics that heat a coil in a toaster. The melted material is then deposited onto the print bed.
  3. The deposition continues as the print head moves, laying down beads of metal that are fused to form fully dense metal parts.

The Joule Printing™ technology has applications in aerospace, automotive, and other consumer product industries. 

11. Water-based Metal Additive Technology

Water-based Metal 3D Printing Technology
Above: Rapidia 3D printing system with the sintering furnace/Image Credit: Rapidia

This unique water-based metal AM technology was developed by a Canadian Startup named, Rapidia. This technology eliminates the debinding stage of metal 3D printing associated with metal 3D printing. This not only expedites the manufacturing process but also simplifies the process and eliminates the need for chemicals.

In this method, water-based metal paste is used to create complex parts. This paste is solvent-free and safe to handle. The Rapidia process uses water to bind the metal powder, making the material safe to handle. The water evaporates during printing, saving time and removing the need for a debinding machine or solvents.

12. Cold Metal Fusion Technology

Cold Metal Fusion Process
Above: Cold Metal Fusion Process/Image Credit: Headmade Materials

The Cold Metal Fusion technology is developed by a German 3D printing company, Headmade Materials. In simple terms, the technology is called Metal Selective Laser Sintering technology. This sinter-based Cold Metal Fusion technology uses an existing ecosystem of machines and processes in 3D printing and powder metallurgy.

The cold metal fusion process uses polymer-coated metal powders. This powder is used in a traditional SLS machine just like any polymer powder. Though the process is called cold metal fusion, the process is not entirely cold.

The printing occurs at 80 degrees Celsius that can be easily achieved by traditional polymer printing systems. The printing process follows the same sequence as a regular SLS 3D printer and builds the part. Since metal printing occurs at very low temperatures, the process is called as Cold Metal Fusion.

The printed part is still in its green state and so before its actual usage, it has to follow a fixed stage of De-powdering, post-processing, debinding, and finally sintering. 

13. Atomic Diffusion Additive Manufacturing (ADAM)

Atomic Diffusion Additive Manufacturing
Above: Atomic Diffusion Additive Manufacturing (ADAM) is a metal 3D printing technology developed by Markforged/Image Source: Markforged

The Atomic Diffusion Additive Manufacturing (ADAM) is one of the most popular metal 3D printing technologies available right now. It is developed by Markforged. It is an end-to-end process that starts with a plastic-bound metal powder that is formed into a 3D shape, one layer at a time. After printing, the part is washed in a debinding solution and sintered in a furnace. The sintering step is crucial in burning off the plastic binder and results in diffusing the metal powder together.

The resulting parts have high accuracy with excellent strength properties allowing manufacturers to use the technology for prototyping, tooling, end-use parts, as well as legacy parts. ADAM is a realistic and cost-effective option for small to medium runs of near net shape metal parts.

ADAM can use a variety of materials like Stainless steel, tool steels, and Inconel is currently used, with copper, titanium, etc.

Conclusion

We saw the top 13 technologies developed by 3D printing companies for use in various and for serving varied applications. There are still more technologies available and even more being developed as you read this article. Depending on the materials to be used and applications to cater, companies can invest in one of multiple technologies to get the most out of the technology.

If you are looking at a comprehensive guide to getting started with understanding metal 3D printing, then you should check out our previous post on Getting Started and also follow for more posts touching upon all the elements of metal 3D printing.

Our next post will cover a comprehensive list of metal 3D printing materials available across technologies and for varied applications.

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About Manufactur3D Magazine: Manufactur3D is an online magazine on 3D printing. which publishes the latest 3D printing news, insights and analysis from all around the world. Visit our 3D Printing Education page to read more such informative articles. To stay up-to-date about the latest happenings in the 3D printing world, like us on Facebook or follow us on LinkedIn and Twitter.