ADDITIVE MANUFACTURING


the surgeon, which takes all the guesswork out of the surgery – the surgeon can perform with confidence, spend less time carrying out the procedure and, therefore, the outcome is better for the patient.’ Tese templates helped the surgeon to make a


reference mark on the bone to help ensure that the custom polyether ether ketone (PEEK) implant was positioned correctly. PEEK is a high-strength plastic used to create patient-specific cranial implants. However, the use of additively


are investigating further materials, both metals and plastics, but a multitude of technical and regulatory requirements must be fulfilled.’ However, plastic additive techniques such as


manufactured plastic implants is usually reserved for complex and bespoke procedures, because of the slow processing times but extremely high quality and resolution of the parts. ‘Depending on the application and the technology, there is a trade-off between the productivity of the laser systems and quality of the parts,’ Zeidler added.


are small, have a lot of complexity and are hard to manufacture conventionally


Spinal cages


selective laser sintering (SLS) have been used for revolutionary medical applications. SLS uses a high-power CO2 laser to fuse small particles of powdered material to create 3D parts. Te laser selectively fuses powdered material by scanning X and Y cross-sections on the surface of a powder bed. Te model is built one layer at a time from supplied 3D CAD data. SLS is capable of producing highly durable parts for real-world testing. One of 3D Systems’ customers


used a 3D body scan and SLS to make custom, lightweight parts for a bionic suit to help a patient confined to a


Material restrictions While 3D printing works with some metallic powders, the conservative nature of the healthcare industry means it is yet to realise the widespread use of additively manufactured composites or more exotic materials. Neumann said: ‘Trumpf systems process metallic powder. Currently, these are mainly titanium and cobalt-chromium alloys in the medical domain thanks to their biocompatibility and suitability for additive manufacturing. Research institutions


Future metal AM


The Fraunhofer focus project, FutureAM, aims to accelerate the additive manufacturing of metal components to reduce manufacturing costs, which would overcome one of the barriers of widespread AM for medical components. Although not directly related to


the medical industry, the research platform was launched in November 2017 and brings together six institutes. Each will develop new digital process chains, scalable and robust AM processes, system technology and automation, as well as expand the range of affordable materials that can be processed. A virtual lab is also planned, in which demonstrator components will be created across the institutes and different disciplines.


Professor Johannes Henrich


Schleifenbaum, coordinator of FutureAM and director of Additive Manufacturing and Functional Layers at Fraunhofer ILT, said: ‘We want to accelerate the actual AM process. All in all, apart from the process costs, we are also addressing post-processing, which is becoming increasingly important, and the automation of the entire process chain. For example, the previous, often still manual removal of the supports will be replaced by intelligent post-processing. To do this, we are working on newer methods, such as removing the supports in chemical baths.’ The FutureAM project will also


address the challenge of making high-precision parts that often hampers large-scale


manufacturing, as Schleifenbaum explained: ‘As a starting point, I would like to look at preheating, because with it the temperature gradients during the process are lower and fewer distortions and stresses occur in the component. This process can be supported by integrated simulation. In addition, according to our research, precision in the tenth of a millimetre range is generally sufficient. If not, then it is better to mill the components to the desired size.’ As a result, the impact of the


FutureAM project means the medical world could be a lot closer to realising widespread additively manufactured personalised implants in three years’ time, when the project concludes. Watch this space.


wheelchair stand upright and walk again. McAlea said: ‘SLS is not quite as accurate as some additive techniques, but the durability is much better. Also, some plastics cannot be sterilised and therefore used in the body, so they are restricted to external use.’ However, additive manufacturing is used to


create plastic spinal cage implants, as McAlea explained: ‘Spinal cages are small, have a lot of complexity and are hard to manufacture conventionally.’ German medical device manufacturer


Emerging Implant Technologies (EIT) recently worked with 3D Systems to create a 3D-printed titanium fusion implant for a patient with a degenerative cervical spine condition. 3D


A cranial plate produced by AM


Systems’ direct metal printing (DMP) technology was used, which is capable of building objects layer by layer in a variety of metals, using biocompatible titanium in this case. Te porous EIT cervical implant imitated the


structure and characteristics of natural trabecular bone. Such porous structures are also used when additively manufacturing other implants, including hip cups, as McAlea explained: ‘We want to encourage bone growth to adhere the implant to the bone. We can do that in one print step, by creating a porous structure on top of a solid structure. Such integrated functionality is another reason why additive manufacturing makes sense for implants.’ Te adaptability of additive to create a range of


sizes at little additional cost is another benefit, as McAlea said: ‘When you get to low to medium volumes, 3D printing opens up other possibilities for the manufacturer, because they can choose to increase the number of sizes they pattern with no penalty. Tere’s no additional tooling or instrumentation required.’ Te shiſt from prototyping to widespread


manufacturing of additively manufactured parts is apparent, according to Neumann, who said: ‘For the past three years, we have seen metal additive manufacturing maturing from a technology predominantly used in prototyping to an almost normal manufacturing technology. Tis transition is changing the way our customers operate our systems and, in turn, how we design our TruPrint 3D printing systems. While, until recently, the ability to manufacture an implant in the first place was important, now factors such as production cost, efficiency and quality come into focus.’ Neumann concluded: ‘Additively


manufactured implants will become cheaper and available to more and more patients, while more and more regulatory bodies create frameworks for additively manufactured implants. Over the long run, additively manufactured personalised implants will gain in momentum.’


12 LASER SYSTEMS EUROPE ISSUE 38 • SPRING 2018 @lasersystemsmag | www.lasersystemseurope.com


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