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Motor out of the 3D-Printer: Robert Hofmann GmbH achieves milestone for tomorrow’s car production

Cylinder block of the company located in Lichtenfels passes practice test on Volkswagen test rig / Significant advantages compared with conventional prototypes

Lichtenfels – Robert Hofmann GmbH from Lichtenfels manufactured the first, fully functional cylinder block, coming completely out of the 3D-printer.
With the component weighing around 25 kilograms, the heart of a motor was produced for the first time in 3D-printing-process. The company located in Upper Franconia already built the cylinder block, also called cylinder crankcase, for a VR6- motor at the turn of the years 2014/15 for Volkswagen. Integrated into a motor, the cylinder crankcase also passed the practice test on a test rig of Volkswagen.

The cylinder block is almost the same as an existing series cylinder crankcase of Volkswagen. Contrary to this cylinder block made of cast iron GJL-250, the model from the 3D-printer, however, consists of the lighter material aluminum. Without costly new construction, the CAD-data of the cast iron cylinder block could be used for the prototype.

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One advantage of the printed cylinder block is the precise manufacturing. The engineers of Volkswagen carried out extensive metallurgic and geometric tests. During these tests, a computer tomography was used as well for checking internal geometries, like for example the cooling jacket around the cylinder tubes.

It showed that the printed cylinder block has low porosity and significantly smaller distortions and deviations from the desired geometry as comparable casted components.

It is a big success for the creative minds of Robert Hofmann GmbH that the cylinder block also functions in a fired motor without problems. “When Volkswagen approached us with the idea to build a complete cylinder block in 3D-printer, we were a bit skeptical in the beginning”, says Michael Dinkel, who manages the project. Volkswagen wanted to investigate the potential of the 3D-printing-technology and convinced the model makers from Lichtenfels, well-known for their innovative solutions, to venture the try.

By now, the cylinder crankcase is the biggest single component, Robert Hofmann GmbH produced in 3D-printing-process. It took 300 hours for the X 1000 R of Concept Laser to build the 25 kilograms cylinder block.

However, work was not yet done at this stage. For post processing of the block, the company from Lichtenfels had to bring in its whole experience once again. Especially the cleaning and removal of support structures constituted a challenge.

The aluminum particles, sticking loosely to the cylinder block after 3D-print had to be sucked off. Cleaning demanded lots of tact, especially in the undercut, which means in the difficultly accessible, narrow areas. Since the cylinder block is designed for cast process, support structures had to be integrated during print. These support structures needed to be removed after production. During this process the support elements had to be sawed out and broken out with high precision, even in areas which are difficult to reach. The close link between workbench and production at Robert Hofmann GmbH made effective work possible here.

Before the cylinder block then could be brought to the test rig by Volkswagen, the component had been completely mechanically processed in Wolfsburg and the cylinder liner provided with an APS-lining.

With the successful running of the motor, Robert Hofmann GmbH and Volkswagen proofed that it is possible to produced functional cylinder blocks with the help of a 3D-Printer – provided the required technical know-how. This could be a milestone for the future of the car industry. Theoretically, the limits of geometry of future motor parts in 3D-printer are not as strict as in cast process, for example.

In future, motor components can be produced in other and more powerful shapes and quicker. The differing mechanical characteristics of the parts produced in 3D-print constitute no restriction here.

Experience the cylinder block live:
If you would like to view the cylinder block at close range, visit us at the Formnext in Frankfurt (15.11. – 18.11.), hall 3.1, stand E30.


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