A Brief Analysis of 3D Printing Technology-Electron Beam Melting (EBM)

-Reprinted from 3D Printing Business

01 What is electron beam melting?

Electron beam melting (EBM) is a 3D printing technology that is very similar to SLS, but EBM has two differences-the energy comes from the electron beam instead of CO2, and the material used is a conductive metal instead of a thermoplastic polymer.

Specifically, EBM typically uses titanium alloys and cannot print plastic or ceramic parts. This is due to the charge on which the entire process is based.

EBM requires conductive metals because the technology itself is charge-based. In other words, the charge is responsible for causing the powder to react with the electron beam, thereby solidifying the powder.

Below we will introduce EBM in more depth, including its working principle, advantages and disadvantages, and some ideal application areas.

02 Electron beam melting process

EBM 3D printed parts post-processing

All EBM 3D printers include an energy source that emits an electron beam, a powder container, a powder feeder, a powder recoater and a heated build platform. The printing process is carried out in a vacuum, so that production can be carried out under strictly controlled conditions. More precisely, the vacuum is mainly to prevent the powder from oxidizing at high temperatures.

The EBM 3D printing process begins by filling a powder bin with the required metal powder. After completion, the powder box is placed into the 3D printer, where the heating phase begins. Before printing, the powder needs to be heated to just below its melting point.

3D printing itself starts with a powder recoater, which deposits a layer of pre-heated powder onto a build platform. Once the powder solidifies, electron beam melting begins. The electron beam is controlled by a set of electromagnetic coils, which precisely point the electron beam to the desired point of the build platform. The electron beam selectively moves as it melts the powder, causing the powder particles to fuse together.

After completing a layer, the build platform moves down one layer's height. The recoater enters again with a new layer of powder, and the electron beam begins to induce a fusion of the powder particles, resulting in the formation of a new layer... This process is repeated until the entire part is completed.

03 Post-processing of electron beam melting

Powder removal from EBM printed parts

When finished, the parts are not immediately visible because they are covered with non-sintering powder in the powder barrel, which must be removed first.
1 Distortion
Since the EBM 3D printing process is surrounded by high temperatures, the part itself is exposed to stress, which can cause deformation. Although the surrounding non-sintered powder provides support for the part during the printing process, it is not enough.

Because of the risk of distortion, EBM requires a support structure. The support is made of the same material as the part itself.

When the part is finally finished, the powder bin is removed from the 3D printer. Although the part has been manufactured, you cannot use the part for the time being.
2 Heat treatment
Due to the molecular stress in the parts, the powder bins containing these parts are printed and then heat treated-heat treatment ensures the elimination of stress, thereby reducing the risk of deformation. Heat treatment also helps to improve the mechanical properties of the parts.

After heat treatment, compressed air was used to expose the part from the powder. If the part has a support structure, remove it after the compressed air has cleared the powder.
3 Support
Since the brackets are made of metal, they are quite strong. Because of this, the removal of support is a common problem for metal 3D printing. As with other metal 3D printing technologies, the support structure is often remote from the part.

After the support is finally removed, the EBM component can be polished, coated or even further processed using conventional techniques, if desired.

04 Advantages and Disadvantages of Electron Beam Melting

EBM 3D Printed Racing Components

Just like other 3D printing technologies, EBM has its advantages and disadvantages.

1 Advantages
· Complete melting of the powder on the basis of high density-the electron beam achieves complete melting of the powder, ensuring a high component density and therefore strength.
· High strength due to high density. It is considered to have the best strength compared to other metal 3D printing technologies.
• Faster printing process.
· Non-sintered powder can be recycled.
• Low risk of warping due to vacuum.

2 Disadvantages
· Small print volume (maximum diameter 350mm, height 380mm);
Less accurate, because the laser spotlight is slightly wider;
Limited choice of materials (titanium or chromium-cobalt alloys only);
Requires skill and time-consuming post-processing;
· Expensive machines and materials ($300/kg)

05 Electron beam melting industry and application

EBM 3D printed skull implant

An interesting fact about the EBM 3D printer is that there is only one company that produces this printer-Arcam EBM, a GE Additive company, which is naturally a leader in EBM.

The price of EBM 3D printers is high. We don't know the exact price because it's not public.

Since EBM 3D printers and powders are expensive, it is not surprising that this technology has not yet been used for mass production. It is mainly used to manufacture small series of parts, which usually have complex structures.

As you would expect from the technology used to make high-strength metal parts, it has been used in many fields. EBM has been used in industries such as medicine, aviation and automotive.

It is worth mentioning that EBM applications were born in the medical industry. With EBM, it is possible to produce fully functional custom cranial implants. Since the EBM part is usually very strong, this part must be as strong or even stronger as the skull.