A new 3D printing technique makes 3D printing in metal significantly less time-consuming. Not only are objects printable faster using the technique, post-processing of printed objects also takes less time.
The technique was developed by a research team led by Franz Haas, head of the Institute of Production Engineering at Austria's TU Graz. The team's technique is called Selective LED-based melting (SLEDM).
Faster than SLM and EBM
At first glance, the technique resembles selective laser melting (SLM) and electron beam melting (EBM), in which powdered metal is cured using lasers or electron beams. By curing the material in specific shapes, it is possible to build an object layer by layer. SLEDM also offers this possibility, but takes less time.
The main difference between SLEDM and SLM or EBM is that in SLEDM, an LED beam melts the metal powder, instead of a laser or electron beam. The LEDs used by the team for this purpose were specially developed by lighting specialist Preworks. For instance, the LEDs feature a complex lens system that allows the focus of the lens to be easily changed between 0.05 and 20 millimetres during the melting process. This allows a larger surface area to be melted at once than is possible with SLM or EBM. The researchers claim that their technique speeds up component printing by a factor of 20 on average.
Less time spent on post-processing
Another important difference is the post-processing, which usually includes removing supporting structures from the printed object. This process largely takes place manually and is therefore time-consuming. With SLEDM technology, this process is partly carried out during the printing process. "The time-consuming, often manual touch-up required with current techniques to smooth rough surfaces and remove supporting structures, for example, is no longer necessary. This saves valuable time," Haas explains.
Graz University of Technology aims to put the SLEDM technique into practice as part of the CAMed project at the Medical University of Graz. As part of this project, a laboratory for medical 3D printing was opened in October 2019. SLEDM is being used to print bioresorbable metal implants. Specifically, these are screws made from a magnesium alloy that is often used to repair bone fractures. The implants dissolve in the human body once the bone fracture has healed. This means that a second operation – which is often very stressful for patients – is no longer necessary.
Other applications
Researchers also see applications outside the medical sector. These include for the production of components for battery system components or bipolar plates for fuel cells. A bipolar plate functions as an anode for one fuel cell and simultaneously as a cathode for the adjacent fuel cell. In the coming period, Haas' team will focus on producing a prototype suitable for the market.
Author: Wouter Hoeffnagel
