Chiselled like a stone: ultra-modern industrial 3D printing with high-tech concrete

The voxeljet company stone – an example for unimagined freedom of design in 3D printing and concrete formwork

voxeljet, Friedberg, December 2017 - From distance it seems simple - but its front has it all. With clear undercuts the voxeljet logo emerging from a rock formation. One might think that in months of fine work, several stonemasons have crafted it from massive stone - but a completely different production technique is hidden behind its genesis: state-of-the-art 3D printing. Instead of ablating material from a solid formation, complex molds are manufactured using binder jetting technology. These molds can later be filled with liquid concrete. The voxeljet company stone combines the latest molding techniques with state-of-the-art high-tech concrete and is the basis for unprecedented applications in architecture and construction.

Nearly every day, 3D printing, also known as additive manufacturing, conquers new fields of application in a wide variety of industries. At the cutting edge: voxeljet as a leading manufacturer of industrial 3D printing systems.

Previously, metal foundries were the main users of the processes offered by voxeljet. 3D printing enables the production of highly complex molds and cores from standard silica sand in the shortest possible time and with maximum precision. Entire work steps such as the design of expensive formwork tools can be saved, since only a CAD file is required to generate sand molds and cores with the aid of 3D printing. The voxeljet service centres around the globe are designed to manufacture these molds on demand.

 

3D printing for concrete casting in the architecture and construction industry

voxeljet´s company stone is a demonstrator for new application possibilities of 3D printing in architecture and the construction industry. Just like metal, concrete can be poured into the sand printed molds. By printing these molds, both reusable and lost formwork is created, depending on the application and complexity of the geometries. The advantage of 3D printing lies in the tool-free, cost-optimized production process. voxeljet´s 3D printing systems allow the production of molds with highly intricate structures in the shortest possible time and with impressive precision. With conventional production methods, such complex shapes could only be produced with great difficulty or might even be completely impossible.

voxeljet sees great potential of applications for concrete casting in architecture and the construction industry. Facades, interior design elements or even furniture can easily be realised with voxeljet's 3D printing systems, as well as objects in the art and design industry.

Without any problems and in the first attempt, voxeljet manufactured the company stone in cooperation with Dade Design Concrete works GmbH, a leading specialist for high-end concrete design and mold making.

The printing process: from the CAD file to the finished real life object

At the beginning there is CAD design. In order to fully utilize the advantages of 3D printing, voxeljet opted for a hybrid formwork, a combination of printed and conventional mold elements. The 3D-printed elements were limited to the complex part, the front of the company stone. Simple geometries, such as straight surfaces, are modelled with conventional wooden formwork.

The complex part of the voxeljet company stone consists mainly of the stone structure with the integrated logo, which emerges from the background structure. The design freedom of 3D printing means, that even highly complex geometries with undercuts and intentional unevenness can be realized without any problems. “With the casting of the company stone, we were able to produce a geometry that could not have been realised in any conventional way" says Tobias King, Director Applications at voxeljet.

In order to start the printing process, the finished CAD file was loaded onto a 3D printing system from voxeljet. The 3D printing system then produced the formwork in one go. voxeljet printed the formwork for the company stone on a VX4000, the largest industrial 3D printing system with a continuous building platform of 4x2x1m (LxWxH), in only one night.

The VX4000 applies sand in an extremely thin layer of only 300 micrometers to the building surface. The print head then bonds the layers selectively with a binding agent. Once the mold is fully printed, voxeljet specialists remove the unprinted sand and clean the mold with compressed air. In order to prepare the mold for concrete casting, the 3D printing specialists infiltrated the mold with a PU dispersion to close pores and simultaneously seal the surface.

Casting of the concrete block

voxeljet then sent the post-processed mold to Dade Design in Switzerland, where it was then casted by the concrete casting professionals.

To make it easier to remove the sand mold from the concrete after casting, Dade Design applied a release agent to the mold. “When it comes to the letters in particular, it is important that the mold can be removed from the casting as easily as possible so that no damage is caused to the concrete later on," says Andy Keel, owner of Dade Design. For Keel, industrial 3D printing “is an innovation that opens up completely new dimensions in concrete mold making. 3D printing allows us to use a fully digital production process, saving us valuable time and effort."

After curing the printed logo, Dade Design poured the rest of the stone in a second step. For this purpose, the concrete casters used a self-compacting concrete, UHPC (Ultra-High Performance Concrete). After about 20 hours the concrete was completely hardened and the formwork was carefully removed.

After removing, the voxeljet block was as good as finished. For the final polish, Dade Design employees used so-called concrete cosmetics, polishing the stone to achieve an even and smooth surface. The results of the first tests in concrete casting are impressive. 3D printer manufacturer voxeljet has thus broadened the horizons of traditional casting with state-of-the-art 3D printing technology and high-end craftsmanship. What would have been unthinkable in architecture in the past is now possible with a combination of 3D printing and our specially developed UHPC concrete," adds concrete casting specialist Keel. The finished stone with the voxeljet logo now adorns the entrance to the voxeljet administration building in Friedberg.