BMW Group Opens New Additive Manufacturing Campus

La Porsche 911 GT2 RS dotée de pistons obtenus par impression 3D.pdf

The Bosch Additive Solution Center in Nuremberg, Germany, has printed a full V8 engine block as a single piece on a Nikon SLM Solutions NXG XII 600 machine.

Printed in AlSi10Mg, the technical demonstration represents a 'clear signal that additive manufacturing is moving beyond prototyping and development,' according to Nikon SLM Solutions.

The metal additive manufacturing company believes the successful 3D printing of the engine proves out the technology's ability to enable complex, high-value automotive applications and compete with and complement conventional manufacturing methods.

While additive manufacturing is a fixture of many automotive development centres, Nikon SLM and Bosch have partnered to establish the technology within the industry's tier 1 and 2 supply networks. By providing its additive manufacturing expertise and capability to a tier 1 automation supplier like Bosch, Nikon SLM is aiming to move AM 'from capability to production reality.'

Their collaboration is going beyond a machine installation and will encompass materials, process parameters, design for additive manufacturing, software integration, and further application development.

With the V8 engine block, the partners believe they have made a strong start. By deploying additive manufacturing for the production of the part, they were able to eliminate tooling - and the lengthy lead times associated with it - and move through design iterations more efficiently. With additive manufacturing, the partners also identified opportunities to integrate cooling channels, engineer topology-optimised structures, and consolidate multi-component assemblies, while also reducing weight by placing material 'precisely where structural analysis shows it is needed.'

Off the back of the successful V8 engine demonstrator, Nikon SLM Solutions suggests that additive manufacturing is ready to manufacture critical automotive components.

Bosch & Nikon SLM Solutions partner for additively manufactured V8 engine block demonstrator

Kakuda would not be drawn to expose the details of the changes, calling them ‘top secret’. However, he admits that ‘we explored many different paths in developing this area and tried many different configurations. We have also developed very accurate simulations to prove our concepts before implementing them into a mechanical system.’ The RBPTH001 takes advantage of a significant amount of additive-manufactured (AM) parts. Kakuda emphasises the fact that additive manufacturing allows engineers to create components with the structure only where load transfers through the part, which is obviously efficient.

‘Additive manufacturing has allowed us to optimise many components, including pistons and the turbocharger housing,’ he says. ‘Although Formula 1 has many restrictions on the materials teams are allowed to use, we have tried many different materials and combinations that fit within the regulations to give us the performance we want for our additive manufactured components.’

Subtractive manufacturing and surface finishing can produce tolerances of as little as 0.2 microns and a Ra 0.2, respectively. This level of refinement is only possible with AM with severe post-processing of the part. Even then, it’s unlikely to be that precise. ‘AM surface finish typically falls within +/- .125mm in the x, y or z direction,’ notes Michael Littrell, CEO of CIDEAS. ‘It’s not uncommon to build a part, measure it and scale areas of the part file to dial in tighter tolerances against the AM part.’

Kevin Lambourne, Managing Director of Graphite AM, says, ‘The tolerance and accuracy is technology and material specific. Ultra-high-resolution AM machines can build to tolerances of 25 microns, but these machines are limited in materials and are only suitable for small components. So, there are still plenty of components that must be manufactured using more traditional methods.’ Fuller added, ‘Surface roughness aside, the microstructure across bulk geometries (>0.5mm) can be consistent, and this is achievable and measurable. In the case of thin walls and microfluidic channels, surface roughness can be the same as the geometric features themselves.

AM software is constantly improving. A significant challenge facing component designers who want to manufacture parts using AM is defining the properties of the layered construction. The problem is that CAD and FEA software cannot define layered material properties because CAD programs work out each structure as an idealization. The structure as it appears out of the AM machine is not ideal – it has very rough surfaces and other imperfections, and the geometry at a microscopic level often diverges significantly from the idealization. Fuller says there have been huge strides across all disciplines of AM when it comes to software for defining the properties of AM construction, but it still needs some discretion.