EOS reports advances in direct metal laser sintering of titanium
24 September 2009
An increasing number of applications involving series production and customised manufacture of parts from titanium powder is reported by EOS, which manufactures additive layer, laser sintering systems at its Krailling factory near Munich.
Since the introduction of the material in 2006 for processing in the company’s EOSINT M 270 system, both the machine technology and the titanium building process have been significantly advanced, leading to higher productivity and improved surface quality of the parts. This has led to increased interest in and use of the technology in a range of industrial and consumer applications.
As well as in the main markets of Europe, North America and Japan, there are now EOSINT M 270 customers using titanium in India and South Africa, with further systems ordered for delivery to South America and Australasia. Customers include industrial end-users, service provider companies and research institutes.
Laser sintering is an attractive production method for many titanium applications. Conventional methods of casting, forging and machining are often difficult and expensive in this material. Following the advent of additive layer e-Manufacturing, titanium is frequently used for producing high value components in relatively small quantities. The ability of the laser sintering process to build hollow and other lightweight structures offers many possibilities for improving the performance and therefore the value of titanium parts in weight-critical applications such as aerospace components.
Titanium alloys have excellent mechanical properties and corrosion resistance combined with low specific weight and good biocompatibility. So far, the main applications for laser sintered titanium are in medical and dental devices, aerospace, motorsport and the fashion industry. The most commonly used material is EOS Titanium TI64, which is Ti6Al4V alloy in fine powder form. In some medical cases, an extra-low interstitial (ELI) version of the powder is used or else commercially pure titanium powder.
Mike Shellabear, Vice President for Metal Technology at EOS, comments, “Titanium applications tend to be extremely demanding. The medical and aerospace markets in particular require excellent component properties and that the production machines and process chains reliably achieve these.
“Now that we have demonstrated that our technology can fulfil these requirements, we see growing interest in and acceptance of DMLS as a production method for titanium. We expect to see rapid growth in this area."
Leader Italia s.r.l. (http://www.leaderitalia.it/) is pioneering the series production of medical devices in titanium by laser sintering. It has developed a range of innovative dental implant screws, called TiXos, which have with exclusive advantages and have been especially designed for production in an EOSINT M 270 using titanium.
Conventionally, such screws are machined from solid metal. In laser sintering, the screws are grown by melting successive layers of the metal powder together, so material wastage is avoided. The laser exposure is controlled to produce a hybrid structure comprising a fully dense body with a porous surface morphology, which eliminates the need for coating and offers enhanced bioactivity. It is also a highly productive process.
As no tooling is needed, different types and sizes of screw can be produced within each build, according to demand. The result is efficient and flexible series production of a high-performance product.
Federico Rizzi, Product Design Manager, says: “Innovative laser-sintering of titanium enables us to computer-design and manufacture dental implants and relative surfaces characterised by intercommunicating cavities that replicate the bone structure, which is impossible to obtain through traditional surface treatment processes. As such, we can contribute to advancing dental implantology to the next level.”
FutureFactories (http://www.futurefactories.com/), a UK-based company founded by Lionel T Dean, has been leading the way in applying the possibilities of additive layer e-Manufacturing to the creation of novel fashion and consumer products.
With the Icon pendant, the company broke new ground by producing a limited edition of commercial products, each unique but based on a common meta-design, thereby implementing mass individualisation. The design is highly complex, comprising intertwining free-form shapes, and was made in titanium, as it would be virtually impossible to produce the piece in this material by conventional methods. Soldering, which is commonly used in jewellery, cannot be applied to titanium.
The laser-sintered pendants are fully dense and polished to produce the desired aesthetic appearance. Lionel T Dean summarises the key benefit: “DMLS freed FutureFactories from the restrictions of the casting process and allowed the company to realise complex CAD geometry directly in metal. Now the first consideration is the form we want to produce rather than the limits of manufacturing."
Kerrie Luft (http://www.kerrieluft.com/) is a British footwear designer who studied at the legendary Cordwainers, part of the London College of Fashion. As Ms Luft explains, “I am creating unique shoes embracing new technologies such as laser sintering, which I utilise in a conceptual way.
My latest collection “nouveau” defines the characteristics of art nouveau by rapid prototyping titanium to create the complex geometry of the heel (an example is shown above). Inspired by nature, I consequently created innovative shapes within both the upper of the shoes and the heels. I love the process of design and making, from taking the initial concept and translating it into collections that are unique and special. Laser-sintering gives me the freedom to do this.”
The filigree structures of the high heels required a high strength material, and titanium was chosen as being ideal. The resulting shoes of her MA collection, with revolutionary heel designs using laser sintered titanium, were showcased at the Mall Galleries in London. This work helped Ms Luft to be shortlisted as a finalist for the Fashion Fringe at Covent Garden Accessories Award 2009.
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