Spotlight: Additive manufacturing

Materials World magazine
,
4 Jan 2017

Ed Littlewood, Marketing Manager of the Medical Dental Products Division at Renishaw, UK, talks to Ellis Davies about using additive manufacturing to create surgical guides and implants. 

Tell me more about your division’s role at Renishaw.

The Medical Dental Products Division spans a few areas – hardware and software supply to laboratories, primarily CAD equipment for scanning and design, manufacturing of frameworks in a variety of materials, supplying medical implants in the cranial maxima facial region of the body direct to EU hospitals and supplying 3D printing metal machines along with an applications package. 

What are the benefits of additive manufacturing in surgical guides and implants?

Implants are generally made using fairly old fashioned methods, such as panel beating, pressing and forming of titanium sheet, casting or laser welding to create the desired shape. Guides are particularly hard to make using any of these techniques, and are traditionally made using a UV-cure polymer. These techniques severely limit the variety of shapes that can be made, and there is not a lot of pre-planning. Designing in a CAD environment allows for virtual planning to check fit and features, which you would not usually be able to. 3D printing is best employed to make surgical guides for use in tandem with the implants.

What are the implants and guides made of?

We use powdered titanium for all medical devices. The guides have been made using AM for a while, but they were previously made of a polymer that was not so resistant to abrasion. When a saw is used on plastic guides, they can potentially warp or deform when sterilised at high temperatures, whereas titanium has a lot more resistance, making it easy to sterilise.

How are the products designed? 

The hospital takes a CT scan of the patient, and then the designer – on-site or third party – imports the data into a software package to convert it into stereolithography data. CT data is a digital imaging and communications in medicine format and comes as a series of slices that can be sifted through to observe different parts of the subject. The software pulls these slices together into a solid STL file, which can then be used to design the implant or guide. 

Are there plans to expand this method to other parts of the body? 

A lot of companies use surgical guides for various other applications. We are currently regulated to cover the facial region and the cranium only, so we do not make guides outside of these areas. There will come a time when we will move down through the body and provide other guides to for other surgeries such as hip or knee replacements. 

We currently supply a guide that can be used in segmenting part of the tibia, allowing surgeons to take a bit of the bone and use it to rebuild a jaw, for instance. 

How cost effective is AM as a means of creating products?

In terms of cost, it’s quite hard to give a definite answer. We believe that 3D-printed products are probably better quality because they are designed for the individual patient, meaning adaption during surgery is not necessary. The surgical times are significantly less, and the implant can potentially perform better during and after surgery when healing. This also cuts costs of later surgery to alter any after-effects. The exact cost of traditional implants is not clear, so it will vary. 

Do you think that AM products can make surgery safer for the patients?

I hope they can. We can’t give a definite answer on that as there is no fixed data to rely on, but I believe that the products make surgery more predictable and safer because of the reduction in time under anaesthetic, a shorter period of concentration for the surgeon and a fully pre-planned operation, which removes a lot of the unknowns.

Will hospitals come to have their own AM machines?

Certainly. I think in certain hospitals overseas this is already being looked into or even trialled. But, it will take a long time for AM machines to become the norm – they are expensive pieces of kit and you would be changing the way that a hospital works considerably. They would enter the world of a manufacturer rather than solely a healthcare provider. 

What machines are used to make the products?

We use our own machines that are made in South Wales. We are currently using the AM 250 in the manufacture of these products, although we have new machines in the pipeline that we are working on making available for similar production methods. From there we have put together a lot of processes that go around the AM 250 and its successor the AM 400 that enable us to make quality implants. 

Trumpf showcases LMD technology

At the 2016 Formnext Trade Exhibition, Germany, in November, German manufacturing technology company Trumpf showcased its latest solutions for laser metal deposition (LMD) technology. The company is focusing on repair applications in the aerospace industry for turbines and compressor blades. 

Alongside this showcase, Trumpf also presented its new additive manufacturing (AM) machines that use LMD – the TruPrint 3000 and TruPrint 5000 – to create products from a powder bed. Trumpf says that its approach to AM is in line with Industry 4.0 protocol, and is looking to put the focus on a complete process chain for AM.  

To boost the impact of LMD, Trumpf has also entered into a partnership with engineering company Siemens. The pair are working together to develop a software solution for the design of AM metal parts to help integrate Trumpfs LMD process into the Siemens NX software. 

GE acquires AM system maker Arcam

Following an agreement to purchase the controlling shares in November, GE, USA, has acquired Arcam, a Swedish additive manufacturing systems maker. Arcam is the inventor of electron beam melting machines, used for metal-based AM, and also produces advanced metal powder for use in the aerospace and orthopaedic industries. The company also operates AP&C, Canada, a metal powders operation, and a medical AM company, DiSanto Technology, USA. 

The acquisition will allow GE to influence the future of Arcam, investing heavily in its products and technology. GE also acquired Concept Laser, Germany, in late October and is looking to use both to supply AM machines, materials and software to several industries including aerospace, power generation, automotive, medical and electronics.

Oerlikon announces new facility

Advanced material provider Oerlikon has announced plans for the building of a new additive manufacturing facility in Michigan, USA. The company says that the site will be dedicated to producing advanced AM materials and high-end surface coatings to meet the demand of industrial applications. 

The new facility is meant to strengthen Oerlikon’s materials capabilities, and prepare the company for the increase in demand predicted for the coming years. The Michigan site will be a base to produce advanced titanium alloys for use in AM, as well as high-end thermal spray powders. An R&D laboratory will also be built at the facility to generate further development of titanium and other alloys, and produce customised powders in small batches. 

Stratasys and Siemens team up

Looking to fulfil a shared vision, Stratasys, UK and Siemens, Germany, have announced a formal partnership to combine Siemens’ Digital Factory solutions with Stratasys’ AM solutions.

The partnership hopes to incorporate AM into the traditional manufacturing workflow to become a universally recognised production practice for industries such as aerospace, automotive, transportation, energy and industrial tooling. Stratasys and Siemens plan to address challenges including delivering robust, repeatable and reliable operational performance from AM across a range of materials. 

Wolf Robotics advance additive manufacturing

Looking to bring metal additive manufacturing (AM) to a larger area, Wolf Robotics, part of Lincoln Electric, USA, has developed a system for producing titanium aerospace parts and low-volume complex parts. The system is a multi-metre build envelope, multi-feedstock and multi-material robotic additive machine. 

Wolf says that this advance will help dramatically expand build envelopes, bringing the process of metal AM to a larger scale. The system is the first of its kind and features a laser powder and laser hot-wire process for steel and titanium materials.