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Fine Powder and Liquefied Metal

Fine Powder and Liquefied Metal

3D printing is becoming ever more important to the Volkswagen Group. The opening of a new center for 3D printing in Wolfsburg testifies to that. But how does this technology actually work?

Whether used for chocolate in the food industry, crowns in dentistry, or components for new vehicles in the automobile industry, over the last decades 3D printing has become one of the most significant technologies of the future. The Volkswagen Group has also been relying on the advantages of this innovative technology for years. It is currently used In the automotive industry mainly for building prototypes, manufacturing special tools and producing finished parts in small batches. With the establishment of a new 3D printing center in Wolfsburg, Volkswagen brand’s toolmaking unit now has the possibility of using 3D printing technology in the production of complex automotive parts.

A good reason, then, to look back at the beginnings of this technology and to find out more about the processes used by the Volkswagen Group.

  • 3D printing is ...

    ... an additive manufacturing technique, by which an object is created by adding, applying, or depositing materials. This process differs from subtractive procedures which involve mechanically removing material by milling, grinding, drilling and other electrical methods to create a specific object. It also differs from forming processes by which an object is formed through the application of mechanical or thermal forces.

From Stereolithography (SLA) to Selective Laser Sintering (SLS)

How Stereolithography works

3D printing was invented by the American Charles “Chuck” Hull. In 1983 he developed a system called stereolithography in order to speed up prototype construction. Only a year later he filed a patent for the stereolithography apparatus (SLA) required for this process. The first 3D printer based on the technology, the SLA-1, followed in 1987. This procedure makes 3D models out of liquid plastics, which solidify step by step when the liquid container they are in is struck by a laser at certain points.

Every 3D printing technology requires a digital 3D file, which is generated using software (CAD). The file is sent to the 3D printer where a second software program (slicer) segments the desired object into thin printing layers. The 3D printer processes the information from the slicer software and begins printing with the help of the instructions.

Stereolithography was followed by various other patents for additive manufacturing techniques from the late 1980s until today. In 1988, for example, the scientist Carl Deckard at the University of Texas filed a patent for the Selective Laser Sintering (SLS) process that is still quite important today. Here, a laser scans the powdered version of a material and fuses the powder materials into a three-dimensional form. In 1989, the American entrepreneur Scott Crump filed a patent application for the fused deposition modeling method (FDM), which is also widely used today. This process involves quickly cooling melted material to harden it.

Volkswagen relies on Selective Laser Melting and Binder Jetting

In its 3D printing centres, the Volkswagen Group uses the selective laser melting process and binder jetting

Since the installation of a 3D metal printer in the Wolfsburg Toolmaking unit in 2014, the Volkswagen Group has been relying on 3D printing technology, and in particular on metallic 3D printing. With the establishment of the Future Pact in 2016 and the commitment to funding in the Innovation Fund II, the Volkswagen Group has made 3D printing an important component of its strategy. Up until now the Group has primarily worked in the area of metallic 3D printing using the Selective Laser Melting Process (SLM). With this method the material to be processed, such as steel for example, is in the form of a fine powder that is applied to the areas where the component is to be made and melted by a laser. The melted powder hardens and forms a solid layer of material. When combined with the other layers, a three-dimensional object is formed.

This is how the Selective Laser Melting Process and Binder Jetting work

With the introduction of a new, state-of-the-art generation of printers at the Toolmaking unit in the Autostadt, the Group is laying the groundwork for the construction of complex automotive parts and serial 3D printing on a larger scale. This new generation of printers was developed jointly with the printer manufacturer HP and the component manufacturer GKN Powder Metallurgy. It is based on the Binder Jetting process, which supplements the Selective Laser Melting Process (SLM) used up to now.

This process involves making components layer by layer and fusing them using metal powder and binding substances (binder). The component formed in this manner is subsequently heated by pressure and formed into a metallic part. Binder Jetting machines make metallic 3D printing not only significantly simpler, but also faster. That, in turn, enables production of a higher number of components. The increased construction rate means that costs are lower than with traditional manufacturing and other 3D metal printing technologies.

The advantages of 3D printing for Volkswagen

In the medium term, 3D printing offers the Volkswagen Group not only the opportunity to do things that aren’t possible with conventional manufacturing – such as the manufacture of a hollow construct. 3D printing also decreases the development time of a new vehicle since parts for making prototypes are available much more quickly than with a conventional process. The Volkswagen Group can also use 3D printing for the cost-effective production of spare parts for antique cars, for example.

In the future, vehicle parts will also be printed in series production. 3D printers will then be used directly at the assembly lines within the vehicle assembly areas, thus automating production bit by bit.