Key for Selective Laser Melting – Gas Flow Management

Credit: am.vdma.org

In additive manufacturing (AM), Gebr. Becker GmbH is active as a systems supplier for gas-proof recirculating fans, filters, and heat exchangers for selective laser melting systems

Could you provide us with a short introduction to Gebr. Becker GmbH?
Christian Radau: Becker is an internationally leading producer of vacuum and compressed air technology. Our products guarantee precise and fast handling, all from transporting raw eggs to moving loads weighing tons, and from contact lenses to chip manufacturing. Becker machines are in use wherever mobile laser systems join steel plates to form underwater parts, flours need to be packed accurate to the gram, or when vacuum-controlled machines count money. Currently, our company has 16 subsidiary companies globally, 30 representations with 800 employees, among them 500 in Germany. We have manufactures at our headquarters in Wuppertal, in Apolda (Thüringen), as well as in Shanghai, China. Each year, we manufacture about 125,000 machines and systems, 80 percent of which are exported. Another important aspect is our close cooperation with universities and research institutes to drive innovation.

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In which areas of additive manufacturing is Becker active?
Radau: As a components and systems supplier, we offer air supply systems, vacuum pumps, and compressors for many areas of mechanical engineering. Part of this is additive manufacturing, in which we have decades worth of experience in the development and production of gas-proof recirculating fans and components for CO₂lasers. Our systems are used in powderbed systems where they guarantee efficient processes and a consistently high quality for printed metal parts. In addition, we offer software, service, as well as application-oriented advice and individually tailored solutions for our customers.

What role do gas recirculation fans, heat exchangers, and filters play in AM systems?
Radau: A protective gas atmosphere is mandatory for selective laser beam melting. Depending on the process and metal powder material, nitrogen or argon are employed as inert gases. It is also necessary to remove any metal splatters and smoke arising during the melting process, as these might impair the already fused component areas, the powderbed, and the laser beam. This is why the process gas flow is parallel to the powderbed. Our gas recirculation fans create the necessary flow. The laying-up depends on system size, installation space volume, and system pressure loss. The filters through which the process gas flows clog up after some time. In order to still keep up gas flow, Becker fans are adjustable. In the same manner, our gas-proof heat exchangers facilitate a constant temperature in the installation space. This is particularly important in processes with high laser output. In addition, our fans are used for pneumatic conveying of metal powders.

Where do you see potential for optimizing gas handling in industrial 3D print processes?
Radau: Quality requirements are always rising, particularly in the production of metal components for high-tech applications. An optimal protective atmosphere and protective gas flow is of special importance, while all this also needs to be adjustable to varying process conditions. There are still other factors for high component qualities: efficient flow across the powderbed without swirling, minimal oxygen content and humidity within the construction chamber. A new requirement has been added, which is to keep up the inert atmosphere all through powder handling. The reason is that manufacturers are integrating more and more preparatory processes and post-processing into AM systems. Our fans and components show the lowest leaking rates, and they are hermetically sealed. In this way, neither can oxygen enter installation space and pneumatic powder conveying, nor can inert gas leak out. In combination with frequency-controlled drives of fans, this is an important contribution to lowering operating costs of AM systems – thus, a true added value.

Does the trend toward automation translate into new requirements for your systems?
Radau: Our fans for AM are based on our VARIAIR technology. This includes frequency converters that already possess various, in part optional communication interfaces. Thus, they are prepared for being integrated into higher-level system control.

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