Safety relief valve AV919 in Additive Manufacturing


Optimal gas pressure in the process chamber is of enormous importance in the 3D printing process, during which metal is melted and formed into the required shape.SLM Solutions Group AG therefore use WITT's AV 919 safety relief valve to keep the gas pressure constant during melting, thus ensuring perfect results.

To handle metals in 3D printing, complex melting processes are needed: the material, e.g. stainless steel, cobalt, chrome or titanium is present in fine powder, that is melted layer by layer with high-performance lasers and built up to a final shape – called Selective Laser Melting.

SLM Solutions Group AG, headquartered in Lübeck, is a specialist in Selective Laser Melting and one of the leading manufacturers of 3D printers for metals. In their machines, the printing is executed under a protective gas atmosphere inside the process chambers. Moreover, the powder management, that is, the fully automated supply, removal and treatment of the metal powder retains this controlled atmosphere.

At the beginning of the 3D printing process, the process chamber is flooded with argon. While the machine’s lasers operate, however, this atmosphere changes: Smoke fumes are created which endanger optimal conditions on the working surface. To ensure a perfect melting process, therefore, a circulation of the protective gas and a constant compensation takes place, but which could potentially lead to uncontrolled pressure increase in the process chamber.

The delicate glass optics of the lasers would be damaged by increased pressure. Highly sensitive Safety Relief Valves of the series AV 919 from WITT therefore keep the chambers’ pressure constant: they open exactly to the set opening pressure and close immediately when the nominal value is again reached. The atmosphere in the process chamber thus remains in the optimum ratio.

"The WITT Safety Relief Valve AV 919 is certainly only a small component of our machines. But without a blow-off valve, which is exactly manufactured according to our individual requirements regarding material and low opening pressure, we could not control the pressure in the process chamber precisely enough," says Andreas Wiesner, Leader for process and material development at SLM Solutions Group AG.

For Andrew Smart, Head of Sales for Gas Safety Devices at WITT, this reflects the core competence of his team: "We design and manufacture small components with great effect. Complex applications and new technologies also require precision and reliability, which we take seriously. "