BMW Group Opens New Additive Manufacturing Campus
La Porsche 911 GT2 RS dotée de pistons obtenus par impression 3D.pdf
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.
‘Design automation and topology optimization tools are now very well suited to AM,’ he remarks. ‘Multi-physics modelling and simulation are utilized to predict manufacturing phenomena (akin to mould flow or weld analysis) and, critically, the advent of in-process monitoring supports a very high level of real-time QA though there is some way to go.’
Most parts produced using AM are designed in 3D CAD and run through a program that turns them into 2D sections that are then fed into the AM machine software as instructions for the build. ‘Conventional CAD/FEM software is developing increasingly in the direction of AM design with new features,’ comments Rawlings. ‘A typical example is thread modelling, and for a few years now, a thread can be modelled and manufactured using the thread feature with just a few clicks. ‘Before that, the thread was only hinted at for a drawing, but there was no physical thread.’
Tech Insight: Additive Manufacturing - Racecar Engineering (racecar-engineering.com)
Additive manufacturing, commonly called 3D Printing, is a manufacturing process that involves melting and stacking sequentially several layers of matter to produce the final part. This process, or processes to be more accurate, can create objects of a large scope of sizes (nanometres to several metres) and of a large variation of materials.