All About Electron Beam Melting (EBM) 3D Printing

Metal 3D printing has transformed how complex metal tooling and parts are made. Electron beam melting, or EBM, is a sound alternative to CNC machining and metal casting due to its ability to print parts with the durability and strength of metals but at the speeds of 3D printing.

EBM is a powder bed fusion process similar to SLM (selective laser melting) and SLS (selective laser sintering) in that each thin layer of metal powder is deposited onto a heated bed and then melted or sintered into place. However, EBM differs from those processes in that the energy source that fuses the powder is an electron beam instead of a laser beam, and the process takes place under a vacuum instead of at atmospheric pressure. Chromium-cobalt and titanium alloys are two of the most commonly used materials in EBM 3D printing.

The history of electron beam melting dates back to 1993, when its principles were first patented by the company Arcam in collaboration with the Chalmers University of Technology in Gothenburg, Sweden. Their goal was to create 3D objects, layer by layer, by melting electrically conductive metal powders with a beam of electrons. In 1997, Arcam was reorganized into Arcam AB, which continued to develop and commercialize the EBM 3D printing process.

In this article, we dive deeper into electron beam melting and discuss everything from what it is, to its advantages and disadvantages, and its similarities and differences from other 3D printing processes.

What Is Electron Beam Melting (EBM)?

Electron beam melting is a 3D printing process that uses electrically conductive metal powders and beams of electrons to produce parts layer by layer. For the process to work, a vacuum of about 0.0001 mbar must be created in the print chamber. In the absence of a vacuum, high-energy electrons collide more frequently with gas molecules, robbing the beam of the energy it needs to complete the printing process. Once a vacuum is obtained, the build platform is heated to extremely high temperatures (around 600-1000℃), and the metal powder is precisely deposited to form the current cross-sectional layer of the part to be printed. At that point, the electron beam meticulously moves about the build platform and uses even higher temperatures to selectively melt and fuse the new powder layer with the previously printed layers. Once a layer is completed, the build platform drops down by an amount equivalent to one layer. This process repeats until the entire part is printed.

What Is the History of EBM Printing?

Electron beam technology dates back to 1869 when Johann Wilhelm Hittorf and William Crookes experimented with cathode rays (another term for electron beams) in gases to melt metals. Their experiments led to a host of discoveries. However, it wasn’t until 1952 that Dr. h.c. Karl-Heinz Steigerwald developed the first practical electron beam processes for commercial use. At that point, electron beams were mainly used for welding applications. More than 40 years later, in 1993, the principles and theory of EBM were first patented by the Swedish company Arcam. This was made possible through collaboration with the Chalmers University of Technology in Gothenburg, Sweden. In 1997, the company was reorganized into Arcam AB as they continued to develop and commercialize the EBM 3D printing process. Arcam AB was acquired by GE in 2016 and integrated into GE Additive.

What Is the Purpose of Electron Beam Melting?

The purpose of electron beam melting is to fabricate metal parts by 3D printing (additive manufacturing). More precisely, electron beam melting is a method of building up a metal component by melting specific patterns of material together, one layer at a time. There are many different approaches to additive manufacturing, but EBM’s purpose specifically is to fabricate using metals with a high melting point. Its application is primarily in constructing complex and intricate parts for the aerospace and medical fields.

What Is the Importance of Electron Beam Melting?

The importance of electron beam melting is that it allows using metals such as titanium and highly alloyed tool steel in 3D printing applications. EBM therefore opens new possibilities for components that can be fabricated. Additive manufacturing allows geometries to be constructed that were previously impossible, particularly parts with complex internals. One of the benefits of this is that multiple components can be fabricated as a single component with additive manufacturing, simplifying assembly. However, additive manufacturing has mostly been developed with thermoplastic materials, as they are relatively cheap and have low melting points. This severely limits the useful application of 3D-printed parts. The importance of electron beam melting is that it can fabricate 3D-printed parts from metals such as titanium and nickel alloys. High melting point metals, with their strength, biocompatibility, and corrosion resistance, open the range of applications that can benefit from additive manufacturing.

How Does Electron Beam Melting Differ From Traditional Manufacturing Methods?

Electron beam melting differs from traditional manufacturing methods as it is a method of additive manufacturing. This means that EBM is used to fabricate by successively adding material (in a specific pattern) to the component being built. This is fundamentally different from traditional manufacturing methods, which either start with a block of metal and remove material to achieve their final shape (i.e., milling and machining) or use molds to cast molten metal into a particular, predetermined shape. These methods typically have a low material efficiency (a high percentage of reprocessed material) and have a long lead time with associated tooling costs. With EBM, a component can be manufactured directly from a digital design, and with no material wastage. However, it is still a young technology, and so equipment and materials are still relatively expensive. These costs are expected to come down as the technology matures.

What Is Electron Beam Melting Used For?

Electron beam melting 3D printing is used for small-batch manufacturing and proof-of-concept verification of parts with complex geometries. EBM systems and the powders used for printing are expensive, hence the process is seldom used for mass production. EBM produces high-strength metal parts, which are mostly used in the aerospace, motorsports, and medical industries. EBM-printed parts are used in high-performance parts such as turbine blades, engine components, medical implants, and prostheses.

What Is Electron Beam Melting Similar To?

Electron beam melting is similar to other powder bed fusion 3D printing processes, like selective laser melting (SLM)  and selective laser sintering (SLS). EBM utilizes a beam of electrons to selectively melt and fuse metal powders to form parts layer by layer. In SLM, a laser selectively melts and fuses metal powders on a heated build platform. SLS is a nearly identical process; however, polymeric powders instead of metal powders are selectively sintered and fused by a laser.

EBM differs from these two processes in the use of an electron beam to create parts rather than a laser, the need for a vacuum in which to print parts, and the need for higher build platform temperatures.

How Does Electron Beam Melting Work?

EBM 3D printing is made possible by a tungsten filament that is heated in a vacuum to create the electron beam. Once the vacuum is obtained, the beam is created, and metal powders are deposited on the build tray, and printing can start. The steps in producing an EBM 3D printed part are described below:

1. Metal powder is deposited onto the build platform to form the current cross-sectional layer of the part to be printed.
2. 3D printer chamber pressure is reduced to around 0.0001 mbar.
3. When the required vacuum level is obtained, the electron beam is turned on and heats the entire build platform to the required temperature (600-1000℃).
4. Once the build platform is heated, the electron beam moves precisely to the build platform to melt and fuse the metal powder particles at even higher temperatures.
5. When one layer is completed, the build platform drops down a height equivalent to one layer.
6. A fresh layer of powder is deposited, and the process repeats until the entire part has been printed.
7. Parts are left to cool—often overnight—before they are removed from the printer.
8. After the parts are cooled, residual semi-sintered powder and support structures must be removed.

What Are the Primary Components of an Electron Beam Melting Machine?

The following are the primary components of an electron beam melting machine:

1. Electron Beam Gun: This is the energy source for the melting. The beam is created from a tungsten filament, but the gun also includes focusing and deflecting coils to direct it to precise locations in the build area for melting.
2. Vacuum (Build) Chamber: The manufacturing process takes place within the vacuum chamber, in which a vacuum is maintained to prevent oxidation of the material.
3. Powder Hopper: The powdered material is held within a powder hopper, from which it is metered out for melting.
4. Powder Roller: The powder roller moves across the build area to evenly spread out a layer of powder. The roller therefore moves across the build area after each layer is melted, to prepare for the next layer to be melted.
5. Build Platform: The build platform is the support for the successively constructed component. The platform descends in minor increments, so that the uppermost edge of the component is at the right height for the next powder layer to be formed.

How Accurate Is Electron Beam Melting?

EBM printing is generally less accurate than SLM printing. This is because, in SLM, the metal powders used are typically finer, and build layers are typically thinner than in EBM. The thicker layers in EBM-printed parts can result in rougher surface finishes. Therefore, post-processing may be required for EBM-printed parts to obtain desired tolerances and surface finishes.

What Materials Can Be Used in Electron Beam Melting?

Only a limited range of metals can be used in EBM. Titanium and chromium-cobalt alloys are two commonly used materials. Certain steel powders and Inconel 718 can also be used. Because electron beam melting 3D printing requires electrically conductive materials to build parts, polymeric and ceramic materials cannot be used.

Can Electron Beam Melting Be Used on Plastics?

No, electron beam melting cannot be used on plastic materials. The vast majority of plastics cannot conduct electricity, and therefore cannot attract an electron beam. Further, the temperatures that are achieved in electron beam melting far exceed the melting point of most plastics, which would cause charring rather than melting.

Can Electron Beam Melting Be Used on Ceramics?

No, electron beam melting cannot be used on typical ceramics. To attract the electron beam, the material receiving the beam needs to be electrically conductive. This generally limits the technology to metallic materials, and most ceramics are not electrically conductive. Although some engineered ceramics are conductive, none of these have currently been developed for use with EBM. 

What Are the Advantages of Electron Beam Melting Printing?

The advantages of EBM 3D printing are:

1. EBM prints high-density parts with good mechanical properties.
2. EBM can print brittle parts that otherwise couldn’t be produced using SLM printing due to the increased print temperatures in EBM.
3. Unused powder can be recycled and used in later print jobs, effectively minimizing waste and reducing costs.
4. The electron beams used in EBM are more powerful than the laser beams used in SLM because the use of a vacuum assures that no foreign molecules can interfere with printing. This higher energy level leads to faster print speeds for EBM compared to SLM.
5. EBM can produce high-quality parts comparable to traditional manufacturing methods like casting or CNC machining.

What Are the Disadvantages of Electron Beam Melting Printing?

The disadvantages of EBM 3D printing are:

1. EBM can be an exceptionally expensive process due to the electron beam technology and metal powders used.
2. Only a limited group of metals can be printed using the EBM process.
3. EBM-printed parts tend to have lower dimensional accuracy compared to SLM-printed parts due to the difference in powder particle size and printed layer height.

What Challenges Does Electron Beam Melting Face?

EBM is a very exciting and promising manufacturing method. However, there are several limitations with the current technology, which limit its use. For one, EBM is only approved to be used with a limited number of materials. More powdered materials and grades suitable to be used with EBM will enable a wider market to be served. 

Another limitation of the technology is that it uses fairly complex equipment. The way that the powdered material is handled within the machine, and spread uniformly across the build surface consistently for hundreds of layers—this requires more complicated machinery than other types of additive manufacturing. The electron beam itself is also a complex energy source.

These aspects combine to form another limitation of EBM—it is still an expensive fabrication technique. It therefore has a narrower set of cost-effective use cases, such as high-value or custom-made components.

What Is the Process Flow of Manufacturing a Part Using Electron Beam Melting?

The first step in manufacturing using the electron beam melting process is to have an electronic 3D model. This model then is processed by “slicing” software, to reduce the 3D component into individual layers to be printed one at a time. The sliced 3D file is then sent to the EBM machine.

At the machine, the first part of the process is to load the powdered material with which to fabricate. The machine will then create a vacuum in the build chamber. This vacuum is necessary to ensure that the electrons in the electron beam do not interact with any gas particles, as well as ensure that the melting metal does not oxidize. 

Once the manufacturing begins, a thin layer of powder is spread across the build area. This powder is first pre-heated, and then the electron beam is used to melt the powder together. The electron beam follows a specific path to melt the powder only in the areas necessary to solidify that layer of the component being built. Once the layer is complete, the build plate (and the component) is lowered marginally, and a new layer of fresh powder is spread across the top of it. This powder is preheated and then melted by the electron beam to create the next layer. Once the part has been completely fabricated, layer by layer, it is removed from the build chamber, and the excess unmelted powder is removed.

What Are the Temperatures Necessary for EBM?

The fusion part of the EBM 3D printing process can require temperatures in excess of 2000℃ to fuse the high melting-point materials typically used in EBM printing projects, such as titanium. Tungsten alloys can require fusion at over 3000℃.

Even the preheat phase of EBM printing demands heating the build platform to 600-1000℃. Preheating the build platform to a high temperature minimizes residual stresses in the printed part, resulting in better mechanical properties. However, a higher build platform temperature requires an adequate amount of support to prevent overhangs from warping.

Supports help conduct heat away from the part and into the build platform—effectively reducing thermal stresses throughout the part.

Why Is the EBM Process Performed in a Vacuum?

The EBM process is performed in a vacuum to reduce residual stresses in printed parts and to prevent oxidation on printed parts due to increased temperatures. If a vacuum is not present, electrons within the beam can collide with molecules present in the air.
This will cause electrons to collide more frequently with gas molecules, robbing the beam of the energy it needs to complete the printing process.
In normal practice, heating metals at high temperatures like the ones found in EBM printing can lead to increased oxidation, which makes the final product brittle. However, in EBM, printing inside a vacuum chamber virtually eliminates oxidation and the lack of ductility and toughness it can cause.

What Types of Products Are Commonly Manufactured Using Electron Beam Melting?

Electron beam melting is commonly used to manufacture metallic products for specialized applications such as turbine blades for jet engines, or custom turbocharger components for motorsport. These types of products are fabricated this way as they can benefit from EBM’s capabilities of fabricating complex parts with materials not suited to typical casting. EBM is also used to 3D print custom titanium (biocompatible) components which are used for implants and prostheses in the medical industry.

What Industries Predominantly Use Electron Beam Melting Technology?

Electron beam melting technology is typically used in industries that require specialized, high-performance components, such as:

1. Aerospace: EBM is used to build turbine blades for jet engines and other critical components in the aerospace industry.
2. Medical: Titanium implants are manufactured by EBM for the medical industry, due to the ability of additive manufacturing to make custom geometries to suit individual patients.
3. Automotive and Motorsport: Custom high-performance parts are manufactured from metals using EBM, together with a faster development time frame than traditional manufacturing methods.

What Are the Applications of Electron Beam Melting?

Electron beam melting applications focus on specialized parts that are fabricated from high-value metals such as titanium or nickel alloys. Therefore, applications of EBM are primarily in the aerospace industry for items such as jet engine turbine blades, or in the motorsport industry for custom turbocharger components. The fact that titanium (which is biocompatible) can be 3D printed by EBM also means that it has applications in the medical field, particularly orthopedics for prostheses like replacement hip joints.

How Has Electron Beam Melting Impacted the Aerospace Industry?

Electron beam manufacturing has impacted the aerospace industry by enabling new, lighter components to be fabricated with new materials. The manufacturing process of EBM is fundamentally different from the traditional process of casting. Building components layer by layer allows different geometries to be built, and different materials (such as titanium aluminide) to be used. An example is the ability to make lighter turbine blades for jet engines, which then provide fuel savings due to the reduced weight. EBM also allows changes to be made to design between units, which casting is incapable of.

Are There Medical Applications for Electron Beam Melting (EBM) Technology?

Yes, there are medical applications for electron beam melting. Titanium alloys are a common material used in EBM, and titanium is also common for medical implants due to its biocompatibility and strength. EBM is primarily applied within orthopedics, in which 3D-printed components such as hip joints are common.

Is Electron Beam Melting (EBM) Used in Engine Component Manufacturing?

Yes, electron beam melting is used in engine component manufacturing in the automotive industry. Due to the cost of a part fabricated with EBM, its use is limited to specialized, high-performance parts such as custom turbochargers. EBM is more commonly used in the aerospace industry to manufacture components for jet engines, such as turbine blades.

What Is the Difference Between EBM and SLM 3D Printing?

SLM (selective laser melting) is an LPBF (laser powder bed fusion) process. The name “SLS” was originally trademarked by SLM Solutions (now Nikon SLM Solutions Group AG), but it is often used as a generic term for metal LPBF systems.

The differences between EBM and SLM 3D printing are:

1. EBM uses electrons to melt powders, while SLM uses photons from a laser to melt metal powders.
2. EBM requires a vacuum to print parts, while SLM prints parts with an inert gas at near-atmospheric pressure.
3. EBM primarily processes titanium, cobalt-chrome, and some nickel-based superalloys, while SLM supports a broader range of metals, including stainless steel, aluminum, and copper.
4. EBM generally prints parts with lower dimensional accuracy and rougher surface than SLM due to its larger powder particle size and the required print layer heights.
5. EBM is more expensive than SLM due to the EBM technology and metal powders that are used.

What Is the Difference Between EBM and DMLS 3D Printing?

DMLS (Direct Metal Laser Sintering) is almost identical to SLM 3D printing. The name DMLS is trademarked by EOS GmbH. Despite the use of the word “sintering,” the process actually melts particles together rather than sinters them.

Aside from a few differences in printing parameters between SLS and DMLS, they are fundamentally the same technologies.

The differences between EBM and DMLS are, therefore, quite similar to those between EBM and DMLS.

1. EBM employs a high-energy electron beam to melt metal powders, while DMLS utilizes a high-powered laser to achieve the same process.
2. EBM operates in a vacuum environment, whereas DMLS functions in an inert gas atmosphere (such as argon or nitrogen) at near-atmospheric pressure.
3. EBM is primarily used for materials like titanium, cobalt-chrome, and certain nickel-based superalloys, while DMLS accommodates a wider variety of metals, including stainless steels, aluminum, tool steels, and titanium.
4. EBM tends to offer lower dimensional precision than DMLS because of larger powder particles and thicker print layers, resulting in rougher surface finishes.
5. EBM machines are generally more costly, though the actual expense varies based on the intended application, material choices, and production needs.