Many industries are undergoing a revolution only known to insiders. At the centre of this change are well-established metal processing technologies and represents another area that is slowly being taken over by laser beams. Selective Laser Melting (SLM) is a technology commonly known as 3D laser printing. SLM does not use traditional technologies such as mechanic milling, cutting and drilling to turn a piece of metal into a required part. The metal part is instead built from the ground up. The raw materials are microscopically fine metal powders. A laser beam melts such a powder into multiple layers until it has turned into exactly the metal part originally constructed by the designer with his CAD system.
The Lübeck-based SLM Solutions Group AG is a pioneer of this new technology. Founded in 2011, the company’s origins date back to 1957. Since 2008, the company has been building its own SLM machines and markets them worldwide. SLM presently employs 340 staff in Lübeck and at branches in Shanghai, Singapore, Detroit, Moscow and soon in Bangalore, India.
The SLM Group focuses on highly-demanding metal processing technology. “We are already working with the fifth generation of these machines,” said Stefan Ritt, head of Global Marketing & Communications, in reference to the rapid development of this technology, originally developed in the mid 90s by a German group of companies in co-operation with the Fraunhofer Institute. Ritt’s 16 years experience as export sales manager means he has vast knowledge of the market and points to annual growth rates of up to 100 per cent.
Shaping metal in a new way
A closer look at SLM quickly reveals the forces driving the market. This new technology allows the realization of metal parts with geometries that are simply impossible to achieve with conventional metal processing. An example are featherweight aluminum designs for the aviation industry that are hollow inside and offer unlimited stability and strength. The SLM Group is co-operating closely with EADS Innovation Works to develop new weight-saving technologies for tomorrow’s aircraft. The automotive industry is also showing keen interest in selective laser melting. Audi’s technology research centre, for instance, works with machines built by the SLM Group. Less weight means reduced fuel consumption and higher loading capacity. Thus focusing on lightweights can yield highly stable, automobile components.
Dramatic changes in medical technology
Changes in medical technology are even more dramatic and Ritt mentioned implants as an example: “Presently, they are primarily made of forged titanium alloy and the surgeon has to decide at the operating table which of the available standard sizes is ideal for his patient. Today, a scan of the patient’s bone structure is made to determine the precise dimensions of an artificial hip joint.” Experiments are done with magnesium metal rails used to support fractured bones during the healing process: “They are simply resorbed by the human body after the broken bone has healed. The goal is to avoid any second surgical procedure only to remove the metal.”
Fiction and reality
Sometimes truly miraculous achievements are related to 3D laser printing. Reports about a rifle that was produced simply based on a set of 3D data downloaded from the internet recently made headlines. “This is only theory,” Ritt concluded and pointed to the limits of SLM technology: “SLM allows for processing any metal that can be welded and the resulting part will have practically the same characteristics as the conventionally processed metal. But when it comes to utmost precision, the part will still have to be refined with conventional mechanical tools.” The same applies when a specific surface quality is required. Such requirements still call for conventional grinding, polishing and coating.
Selective laser melting is still slower and more expensive than conventional metal processing technologies. But the revolution is on its way and nobody can stop it. Soon, designers will no longer have to worry about the technically possible and can simply design the required part.
Sources and further information: