Tungsten 3D Printing at the Karlsruhe Institute of Technology
Tungsten (W) is an extremely hard metal that is both expensive and time consuming to machine, making the production of tools and shapes both expensive and laborious.
KIT researchers have devised an innovative 3d printer metal powder technique for producing tungsten in any desired shape, which could significantly cut costs and production times while providing improved protection against radiation rays in medical accelerators. Furthermore, this new process can also be used to make collimators shields to shield medical accelerators against harmful radiation rays.
Extrusion
Tungsten is an extremely dense metal with a high melting point that makes it suitable for many uses in various industries, including radiation shielding in nuclear and medical settings. Unfortunately, its hardness and melting point have traditionally made production difficult.
Researchers from Karlsruhe Institute of Technology have successfully printed tungsten (wolfram) with a commercial 3d printed aluminum using electron beam melting (EBM), which accelerates electrons to melt metal powder. This reduces strain in the material and produces soft yet workable materials which can be directly used.
Researchers’ results demonstrated that direct ink printing of a slurry consisting of WO3–0.05% NiO submicron powders produced 3D microlattices with overall 50 percent open porosity consisting of 85%-90% dense tungsten struts — showing improved X-ray attenuation properties when compared with pure polycarbonate structures — making this method suitable for manufacturing complex-shaped components used in fusion energy and medical engineering applications.
Build Volume
Tungsten is an extremely hard metal with great corrosion resistance and one of the highest melting points among all known elements, making it perfect for use as tools or balance weights — however it’s difficult to work with, often cost prohibitive when produced conventionally, and has an extreme melting point that makes 3d printing powders it an additional challenge.
Army engineers have developed an innovative laser powder bed fusion (LPB) process to print crack-free tungsten parts. This technique uses an iron, nickel and zirconium alloy binder as part of the binder mixture in order to lower risk of microcracks in printed parts.
Amiga Metal Additive Manufacturing now offers additively manufactured pure tungsten that’s ideal for medical, nuclear, defence and tooling applications — thanks to work performed by the US Army. Amiga has expanded their Metal Additive Manufacturing collection with pure tungsten that comes in an ideal spherical form suited for x-ray collimators — they’re the only UK company capable of using this innovative technique of controlled processing of this form of metal!
Filament
Tungsten (wolfram) is an exceptional metal with high density and hardness, as well as being safe to handle at extreme temperatures. Unfortunately, its application was once restricted due to expensive and complex equipment requirements; now though, the Karlsruhe Institute of Technology has achieved success printing tungsten with their 3D printer!
Rapid 3DShield Tungsten contains 91–93 percent pure metal and can be printed using any open-architecture Fused Filament Fabrication (FFF) printer. Printed without debinding or sintering, it makes an excellent material for radiation shielding applications in medical, security, nondestructive testing and x-ray fluorescence radiation protection environments.
Tungsten requires a higher temperature range due to its vulnerability to chemical attacks than other materials, so direct drive printers work best and should extrude at slower speeds so as to avoid clogging up its extruder. Stringing will inevitably occur; however, making this option much cheaper than powder injection molding which involves advanced manufacturing technology.
Temperature
Tungsten is an exceptional heavy, dense metal with corrosion-resistance and radiation shielding capabilities, yet its high melting point and brittleness make it challenging to work with. Traditional methods require extensive processing time before cracks begin appearing — not an ideal situation when dealing with such an unpredictable metal!
Researchers from Karlsruhe Institute of Technology (KIT) have successfully managed to overcome these limitations by adapting electron beam melting (EBM), in which metal powder’s atomic composition can be adjusted with electric current, into printing without cracking. This process reduces strain on tungsten while still permitting printing without cracking.
Heraeus implemented EBM technology to produce tungsten collimators for use with medical accelerators. These collimators replace lead components in their radiation head and help protect people and objects from exposure to radiation ionizing radiation rays. This application demonstrates metal additive manufacturing’s potential in radiation protection applications; research was funded by German Federal Ministry for Education and Research through MESA project funding.
