Researchers at the Institute for Manufacturing Technology at Graz University of Technology (TU Graz), Austria, have developed a new technology for metal Additive Manufacturing called Selective LED based Melting (SLEDM), involving the targeted melting of metal powder using LED light sources. The researches have applied for a patent on the new process.
The technology is similar to Laser Powder Bed Fusion (L-PBF) or Electron Beam Melting (EBM), but reportedly eliminates two central problems of powder bed-based Additive Manufacturing; the time-consuming production of large-volume metal components, and the time-consuming manual reworking required.
According to Franz Haas, head of the Institute for Manufacturing Technology at TU Graz, in SLEDM metal powder is melted using a high-performance LED beam. The light-emitting diodes used for this were specially adapted by lighting specialist Preworks and equipped with a complex lens system with which the diameter of the LED focus can be easily changed between 0.05 and 20 millimetres during the melting process. This enables larger volumes to be melted per unit of time, without having to do without filigree internal structures, and thus reduces the production time of components, for example for fuel cell or medical technology, by a factor of twenty.
This technology is combined with a newly designed production system, which– in contrast to other AM systems – assembles the component from top to bottom. This is said to reduce the amount of powder required and enable the necessary post-processing to be carried out during the Additive Manufacturing process.
The demonstrator of the SLEDM process is already believed to be included in the K project CAMed of the Medical University of Graz, where the first laboratory for medical Additive Manufacturing was opened in October 2019.
Here, SLEDM will be used to produce bioresorbable metal implants – primarily screws that are made of magnesium alloys and used in the repair of broken bones. These implants dissolve in the body after the fracture has grown together, meaning that a second operation is unnecessary. The researchers believe that, using SLEDM, it may be possible to produce such implants directly in the operating room, as an LED light is less dangerous to use in the operating theatre than a powerful laser.
The second focus for the SLEDM process is on sustainable mobility, namely in the manufacture of components such as bipolar plates for fuel cells or components for battery systems. Haas plans to produce a marketable prototype of the metal Additive Manufacturing machine in the next development step.