3D printers and their extended family of additive manufacturing (AM) tools have been dismissed by some as being too slow for mass-production, but there are game-changing opportunities on the horizon – as highlighted at yesterday’s industry summit in London. Big names such as Airbus, Boeing, EADS, Bayer, IBM and Volvo are looking at the technology in a positive light.
Bernhard Müller from the Fraunhofer Institute for Machine Tools and Forming Technology began the day by summarizing the state of play, pointing out AM’s origins as a design tool, but adding that production teams are becoming more involved with the technology.
Dyson is one of many, many firms making great use of AM for rapid prototyping and has three EOS selective laser sintering machines, two Ipro 8000 stereolithography systems and two Eden Objet 3D printers running almost full-time to road-test new product ideas.
But Jessica Middlemiss, senior materials engineer at the firm, flagged up the mismatch between the material properties of the AM components compared with downstream injection moulded versions – an issue that makes it much harder to predict final product performance.
Help could be on its way though.
Thomas Buesgen, senior project manager 3D printing at Bayer Material Science, revealed that they are working hard to provide materials for AM that are more elastic, highlighting a new product – TPU 92A-1 – a thermoplastic designed for SLS systems that is being marketed as the first fully-functional flexible material in 3D printing.
Buesgen also observes that the injection moulding sector is keeping a much closer eye on AM, another sign that layer-by-layer assembly is being taken more seriously in manufacturing circles.
One injection moulding tool-maker, Arburg, has even made a move into AM with its “Freeformer” system, unveiled in October with much fanfare at the K show in Düsseldorf. The tool features an injection moulding style chamber, but is coupled to a piezo-driven nozzle that sits above a 5-axis building plate, and dispenses material point-by-point.
Nobody is suggesting that AM will ever replace injection moulding, certainly not for high-volume production runs (Dyson makes more than 206 million components a month!) But AM does have some aces in its hand.
Complexity for free
Typically, the overall price of production ramps up with the complexity of the part, but with AM the cost curve is much flatter thanks to the layer-by-layer nature of the fabrication process. With AM, a simple part costs more or less the same as an intricate one, which has given rise to the phrase – “complexity for free.”
This is music to the ears of designers, but requires a re-think when it comes to software.
Validating AM designs using standard software tools is difficult on two counts. One – the need for massive computing resolution to accurately map out what tend to be intricate and increasingly bio-inspred designs, and two – a lack of AM-specific experimental data to feed into the model.
For example, Jan Sehrt, head engineer at the Institute of Product Engineering, University of Duisburg-Essen, made the point that AM parts don’t have consistent material properties. The strength of component varies depending on the orientation of the build. He showed data for a simple bar that featured 400 material layers when built on its side, rising to 2500 layers when assembled vertically.
Despite the technical hurdles, the potential of AM for sectors such as aerospace is huge. Today, plane-makers have to mill their giant-sized components from blocks of titanium, which is costing firms such as Airbus and Boeing a fortune – as much as 90% of the material has to be removed to create the part (and recycling doesn’t do much to soften the expense). AM would significantly reduce the amount of waste for an identical design, but also gives developers the means to put weight-saving opportunities to the test through topology optimization (see “EADS casestudy using Optistruct” – PDF).
Another great fit for AM is the medical sector driven by the ability to make custom parts such as dental crowns or replacement joints, something TMR+ has touched on in a previous post.
There are more applications too. Mark Miodownik, director of UCL’s Institute of Making, highlighted the example of a tissue scaffold formed by 3D printing that allowed surgeons to repair a patient’s windpipe. AM was a success here because it allows you to place air where you want, and this “designer porosity” is very important for cell growth.
Miodownik is a big fan of AM, recognizing the suite of tools as a way of “unifying expertise across different length scales.” In other words, bringing together physicists, chemists, people with nanotechnology know-how, materials experts, medics and engineers to translate ideas into products and devices. He does adds that this will require machines that can print with much greater resolution than is possible today. For example, to make fully fractal porous media – something his colleagues are keen to do.
Metamaterials to the rescue
Another shortcoming of AM that often gets flagged up is the difficulty of printing multiple materials in the same process. There has been progress using a carousel approach (YouTube clip), but Miodownik reminds the audience that AM makes it very easy to make local changes in geometry, so much so that you might not need to use multiple materials as often as you think.
For example, portions of a component can be stiffened while other areas can be allowed to flex just by changing the material thickness or by introducing holes. Beyond this, you can add sticky regions by incorporating tiny Velcro-style hooks or in the future maybe even gecko-like hairs. Also, researchers in the US demonstrated earlier this year how a 3D printer could be used to print an invisibility cloak to steer radiation around an object, in this case at microwave frequencies.
So how will the AM landscape play out?
Some parts of picture are easier to predict than others. The rapid prototyping area is likely to go from strength to strength. Here, the assumption is that AM tools will follow the path of PCs giving customers more and more performance for the same price.
AM will see production success first with the manufacture of non-critical parts, such as plastic caps and covers. Companies such as Volvo are keen to adopt AM as a way of streamlining its logistic channels for after-market spare parts.
Other firms watching with interest include IBM, which sees AM as a market for software and cloud solutions as developers push their ideas around the world to local production sites.
Beyond that, it was Christian Lindemann from the Direct Manufacturing Research Center at the University of Paderborn that picked up the discussion. He’s part of a team that is busy mapping out the potential future for AM based on a combination of industry needs and research intensity in a series of studies dubbed – Thinking ahead: the future of additive manufacturing.
You can discover their conclusions so far by visiting – http://dmrc.uni-paderborn.de/downloads/
Further reading on the web –