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3D printing under intense pressure
Fine for prototypes, but not suitable for chemical equipment, especially under high temperature and intense pressure? There are persistent prejudices surrounding metallic 3D printing: too porous, inferior quality, and ultimately not weldable. A new chemical reactor from WACKER now proves the opposite, paving the way for new process and product designs.
People tend to think of chemistry as involving bangs and smells. To make sure it doesn’t come to that, chemical reactions take place in specially designed reactors. The temperature, pressure and material flows inside these reactors can be precisely controlled so that the desired chemical reactions take place in a defined manner. To design such reactors, the delicate handling shown by our chemists is just as important as the technical expertise of our engineers, skilled manual workers and design engineers. Now they have achieved a sensation: a reactor that is printed and welded from metal and which can withstand temperatures of 150 °C and, above all, 100 bar.
The welded joints between the 3D-printed components had to be of the highest quality as well. The design would not have been possible using conventional manufacturing processes. It was new territory for metallic 3D printing too.
“3D printing has hardly played a part so far when it comes to designing apparatus and pressure equipment,” says Tobias Stecher, 3D printing specialist at WACKER’s Engineering unit. The doubts about strength and quality were too great, he added. Together with project manager Johannes Voggenreiter, the team disproved these assumptions. Acting as a bridge between laboratory tests and industrial production, a small, very flexible reactor with a volume of 12 liters was needed for the development of new polymer products.
Structural design not feasible with conventional methods
The insides of a 3D printer. This type of printer produces metallic components using the selective laser melting process (©KSB SE & Co. KGaA)
The design included countless connections, hidden undercuts and extremely fine cooling channels. The required design would not have been possible using conventional manufacturing methods such as milling, turning or welding – and certainly not with the required compressive strength.
The reactor was therefore printed in six individual sections from a nickel-base alloy at KSB in Pegnitz using a selective laser melting (SLM) process. A laser melts ultrapure powdered metal layer by layer into a solid shape. The result is a component with a complex design and a material that is around 30 percent stronger than conventionally manufactured components. The individual parts were then welded together at WACKER’s central workshops, all the while ensuring the highest quality, because the welded joints could not in any way be inferior to the strength of the printed material. This presented even experienced skilled workers with new challenges, especially when it came to the precise welding and turning of the individual components. Production extending from 3D printing right through to the inspected reactor took just three months or so to complete.
“The biggest challenge was the interaction between the structural design, strength calculation and TÜV testing phases,” summarizes designer Christian Lang. Thanks to the outstanding cooperation of all those involved, the innovative component was successfully certified by TÜV in accordance with the Pressure Equipment Directive, achieving the highest category of 4. “The collaboration between WACKER, TÜV and KSB was extremely close, professional and uncomplicated right from the start,” confirms Andreas Hopfengärtner from 3D printing partner KSB, “Together, we were able to successfully drive forward an exciting, innovative and cutting-edge project with the construction of the reactor prototype.”
The reactor passed extensive procedural and non-destructive tests – making it one of the first pressure-bearing components in this category to be manufactured using a combination of conventional welding techniques and 3D printing. It will now be deployed in the pilot plant run by the Polymers division.
Playground for new molecules and processes
Layer by layer, a laser melts ultrapure powdered metal into a solid shape – recorded using a strong fadeout and a very long shutter speed, which makes the interior details and variations in light visible to particularly impressive effect. (©KSB SE & Co. KGaA)
The new pilot reactor shows the potential of metal 3D printing. It makes new molecular designs possible because different conditions and chemicals can be combined in a very small space. This shortens our plant-development processes and enables us to validate and develop product ideas faster and market them sooner. Additive manufacturing opens up new degrees of freedom in design, functionality and process integration. Together with WACKER’s comprehensive structural-design and engineering expertise, this type of manufacturing lays the foundation for further innovative and highly integrated equipment and processes. What is more, the process, economically speaking, is particularly attractive whenever conventional production reaches its limits or a large number of complex construction process steps can be combined into a single step.
As the installation space of 3D printers grows and the range of materials – from stainless steel and nickel alloys to copper or silver – becomes ever wider, additive manufacturing will continue to gain in importance. The high-pressure reactor is therefore not only a technical masterpiece, but also shows how WACKER is driving innovation forward.
More about research & development at WACKER
WACKER is a global company driven by in-depth research. Providing impetus for innovative products and applications, we are a technological driving force in many industrial sectors.
