27 Mar 2018
'Spheroidized' form of hard-wearing metal thought to be well suited to laser additive processes.
A collaboration between UK and US companies is working to demonstrate the suitability of tantalum in a “spheroidized” form for laser additive manufacturing.
Pittsburgh-based metals provider Global Advanced Metals Pty Ltd (GAM), which specializes in tantalum and niobium products, is co-operating on the approach with UK-headquartered metal powder vendor LPW Technology.
They are aiming to demonstrate the suitability of the spheroidized form of so-called refractory metals for additive production, saying that there is a need for a more thorough proof-of-concept, and development of print criteria. “GAM is filling this void and expanding its product portfolio,” stated the two companies.
Chemically inert, and extremely resistant to both corrosion and heat, tantalum is already used in medical applications – mainly orthopedic procedures such as replacement joints.
But because of those same chemical properties, the metal is extremely difficult to process using conventional approaches: tantalum cannot be soldered, while any welding must take place under helium or argon gas, and its sheer hardness makes grinding difficult.
Those challenges suggest that additive techniques could prove valuable, and according to local reports, the world’s first 3D-printed tantalum knee replacement surgery was carried out on a patient in China late last year.
Two years ago, welding specialists at UK-based TWI [The Welding Institute] set up an industry partnership with metal powder provider Metalysis, looking to demonstrate the feasibility of its tantalum powder in metal additive layer manufacturing for biomedical applications including patient-bespoke hip joints.
That work focused on production of lattice structures, using selective laser melting as the additive technique. TWI stated at the time that the approach should result in the ability to make tantalum parts much more cheaply than with the inefficient and highly toxic conventional approaches.
“Metal 3D-printed hip replacements could be a huge step forward, allowing patients to have a tailor-made joint by scanning their other hip and matching it with a metal 3D-printed replacement, rather than being restricted to the choice of standard sizes now available,” it noted.
£20 million facility
GAM reckons that the successful demonstration of laser 3D printing of tantalum will offer its customers another powder option with which to serve medical, dental, military, aerospace and other markets via tantalum-based additive manufacturing.
“Tantalum offers superior osteointegration, higher biocompatibility and reduced stress shielding with respect to current metals and alloys used for medical implants,” stated the firm.
Company CEO Andrew O’Donovan added: “We can now measure and share physicochemical data for both our spherical tantalum and the resulting 3D printed part and bring this solution to our partners, for example practitioners, designers and manufacturers of tantalum-based surgical implants and other high-reliability and critical devices.”
LPW’s COO Ben Ferrar said that the collaboration with GAM would help expand the materials knowledge-base for additive manufacturing (AM) more generally, and help to accelerate its adoption in volume production.
“The performance of metal powder feedstock is key to building consistent AM parts and delivering the required mechanical properties,” he said. “This work will further develop understanding of the factors affecting tantalum powder spheroidization and how it performs in the AM process, adding assurance to metal AM producers of the material compatibility for AM production.”
LPW is in the process of completing a new £20 million state-of-the-art facility dedicated to producing high-quality metal powders suitable for additive manufacturing.
The purpose-built site, near Liverpool in the north-west of England, is focused on safety-critical applications in the medical, aerospace, and automotive markets, and is said to introduce full material traceability, digital integration and strict contamination control to the production process.