The selective laser melting (also known as the powder bed fusion) is an additive manufacturing technology that has the ability to melt a thin layer of dust (metal, ceramic, etc.) thanks to the use of a high power laser. The laser gradually and locally fuses the powder in a controlled atmosphere and allows, thanks to the layering, the production of metallic parts.
The Tecnalia research center has developed, in collaboration with the University of the Basque Country (UPV / EHU) and Ibarmia, a hybrid manufacturing machine. This machine combines two technologies:
- Additive Manufacturing Technology: LMD Powder
- Subtractive manufacturing technology: Machining center
Thanks to this new hybrid technology, it is possible to obtain both the advantages of additive manufacturing and the advantages of machining without having the major disadvantages: surface finish not smooth in LMD and excessive loss of material during machining from a block.
This technology, called electron beam melting, is similar to SLM technology, as it is also based on fusion of the powder deposed on a thin layer called bed. However, the main difference is that the laser used in SLM is replaced by an electron beam. The electron beam is obtained by heating under vacuum a tungsten filament. The electrons are accelerated and directed through electromagnets. This laser beam strikes the surface of the workpiece and melts the powder locally. It is important to emphasize that this technology requires electric conductor powder, otherwise the electromagnets would not act.
This technology responds to the principle of powder deposition (metallic, ceramic, etc.) on the melting face of a metallic part. The molten powder, directly on the surface, forms a layer that fuses with the piece. The sequence of layers forms the part, and also can be used for the part reapration. In fact, this technique allows to build pieces complitely, but can also be used in the repairation of damaged parts, or in the realization of superficial treatments. This process has an important advantage over the metallurgical cohesion between the added powder and the piece surface.
This technology, similar to welding, uses an electric arc to melt a metal wire directly onto the surface. The assembly is mounted and controlled on a robotic arm. This technology is the most promising for the manufacture of large metallic parts.