Pocket-sized innovation: How we 3D-printed the test tower

Engineering | innovation | Innovation to go? Every year thousands of people visit our test tower for elevators in Rottweil, North Rhine-Westphalia in Germany. Now visitors can get their hands on a miniature version of our tower. The new souvenir is not only nice to look at: it bears a lot of innovative 3D-print technology in its' 127,94 millimeters and 15 grams made of thermoplastic.

With 232 meters, the test tower for elevators in Rottweil is Germany’s highest visitor platform. It attracts thousands of visitors every year. We would like to thank them for their enthusiasm and the ongoing interest in our test tower. That’s why our experts from the TechCenter for Additive Manufacturing in Mülheim an der Ruhr joined forces with the elevator specialists from Rottweil to create a small piece of high-tech: A miniature tower straight out of the 3D-printer.

Testturm, Rottweil

The test tower in Rottweil is not only a test site for our latest elevators, but also a magnet for tourists.

Additive manufacturing you can touch

The miniature version of the tower is manufactured according to the designs of the architects Werner Sobek and Helmut Jahn and is produced using the selective laser sintering process at the thyssenkrupp TechCenter.  This 3D-printing process enables the production of highly intricate shapes.

The 3D-printed mini test tower stands for thyssenkrupp’s innovative strength,” says test tower marketing expert Christiane von der Trappen. “Our visitors have long wished for a small tower to take home with them. Here in our test tower, the elevator systems of the future are being tested. MULTI is currently revolutionizing the elevator industry and will be exhibited next year in the German Pavilion at Expo 2020 in Dubai. That’s why we wanted to offer an extraordinary souvenir.”

Selective laser sintering process: Parallel production layer by layer

In the selective laser sintering process (SLS), thermoplastic powder is applied layer by layer to the building platform in the form of thermoplastic powder. The floor of the previously heated installation space is completely covered with wafer-thin powder layers. During the production process, individual as well as several components can be produced simultaneously. That’s how 100 miniature towers are produced in a single component layer at the same time in the TechCenter for Additive Manufacturing.

TechCenter, Additive Manufacturing

At the TechCenter in Mülheim an der Ruhr, technical drawings from all over the world arrive, which are converted into digital models by the innovative software on site.

The information about which area is lasered and melted into the corresponding structure is taken from the digital construction drawing by the SLS software. To apply the next layer, the construction platform is lowered a little and the process is repeated. The special feature is that the entire installation space of the printer is filled layer by layer with powder, so that the remaining, unmelted powder remains in the space and carries the melted part. Thus the cuboid can be used almost completely. High-precision components can be laser-sintered into the three-dimensional space independently of gravity.

Tool-free manufacturing process with unlimited design freedom

The SLS process thus offers the possibility of manufacturing products with design freedom and precision unknown for 3D-printing processes. There are almost no limits to the variety of shapes and designs.

As shown in the video, the finished parts, in this case the small test towers, are buried under raw material powder and then removed. Only after clearing the towers of all powder residue by air pressure, their details come to light. In contrast to subtractive processes such as turning and milling, in which material is removed, the SLS process is an additive process in which material is applied layer by layer. This means, among other things, that laser sintering is a tool-free process. In subtractive processes such as CNC turning, for example, there is the turning tool with the respective cutting wedge, which removes material and is subjected to very high stress due to surface contact. The costs for provision, wear and replacement of these tools are saved with additive processes such as selective laser sintering.

Location-independent production thanks to 3D-printing

“We receive a technical drawing from our colleagues in Rottweil, which we can then use to convert the technical drawing into a digital model,” says Thomas Rheinhardt, Senior Engineer AM Plastic & Solutions, describing the first steps in the production of the test tower souvenir. The production chain begins with the transmission of data. This is another advantage of the laser sintering process: it is location-independent. That way companies all over the world can communicate with each other. Development and production take place separately. Additive manufacturing makes it possible to produce complex plastic or metal components for industrial use efficiently and less time-consuming.

global engineering, additive manufacturing

Selective laser sintering facilitates global communication within the field of Additive Manufacturing.

The result: A test tower to go

The tower consists of technical thermoplastic PA 12 and is manufactured in a sintering plant of the EOS P396 model in Mülheim an der Ruhr. Initially, it will be available as a limited first edition with a quantity of 572 units. Each unit is identified by a serial number. The miniature version of the test tower uses additive manufacturing to reproduce the Rottweiler original in detail. As the individual layers are thinner than a sheet of paper, the transitions are hardly visible at more than 1,000 layers in a single tower. The test tower 3D-prints are available for 25 euros a piece in the test tower in Rottweil and in our online shop.

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