The custom 3D-printing filament that will help keep a world-leading neutron source at the top of its game
09 Jul 2026
Additive manufacturing, also known as 3D printing, has exploded in popularity in recent years. With the right design knowledge, you can print anything from fidget spinners to surgical implants. But did you know that it can also help us manufacture important components for instruments at major science facilities, using special custom-made filaments?
Our new in-house filament manufacturing capability will be used to print custom boron carbide collimators for the ISIS Neutron and Muon Source, enabling crucial instrument upgrades for their Endeavour programme.
With traditional manufacturing processes, ISIS’s upgraded HRPD-X instrument would use resin-sprayed sheet metal for its collimator, a specialised device that transmits the neutrons researchers want to measure while blocking the ones they don’t.
Instead, through a collaboration between Technology, ISIS and the Paul Scherrer Institute (PSI) in Switzerland, the instrument will be 3D-printed using custom-made boron carbide filament.
This new process will replace the hands-on sticky resin work, freeing up our technicians’ time and resulting in a safer, more efficient, and more accurate manufacturing process.
Commercial boron-based filament is both expensive and of varying quality – without even considering the difficulty of sourcing filaments of the higher boron percentage needed for this project.
So, we decided to make our own.
Transforming plastic into ‘gold’
Our filament-producing workshop is tucked away in a quiet corner of Rutherford Appleton Laboratory, with a long manufacturing line reminiscent of a Rube Goldberg Machine.
Controlled by our resident experts, Joel Hodder (Technology) and Rafael Heeb (PSI and Technology), the specialised equipment can transform polymer and powdered boron into a high-tolerance filament.
This process first involves loading the base filament components into an extruder, which, after about four minutes, squeezes out a sticky plastic thread.
This thread is carefully grabbed with a pair of pliers before being guided along a four-metre-long cooling bath.
Once fully stretched, an air knife (think a strong Dyson hand dryer) blows off any remaining water, while a laser measures the plastic’s diameter and ovality.
A modified puller then draws the plastic through at a speed to match the final filament’s desired diameter.
In the end, you are left with a spooled polymer composite filament, ready to be fed into a 3D printer.
There is also a contraption on hand, with diamond blades, to shred flawed filament and start again if needed.
Although it cannot be recycled infinitely, after three to four cycles through the machine, the polymer becomes degraded.
Joel shared: “We have produced filament reliably at 40% boron content, but going up to 50 – 60% the filament is too brittle and difficult to load onto the reels that load the printers.”
While this may be the case, Rafael is hard at work, investigating how to reduce the filament brittleness as part of the project’s ongoing development.
From a rare isotope to a finished instrument component
HRPD-X is a significant upgrade to ISIS’s existing HRPD instrument, expanding its user base into new areas of research, such as sustainable technologies for carbon capture and storage.
The final printed collimator is due for installation in late 2027 and will be made of boron-10.
It will cost tens of thousands of pounds to acquire the three to five kilos of this rare material needed to print the collimator, making our team’s early analysis of the mixing and extrusion process vital.
However, this is not the end of the story.
The collimator will eventually need to be printed on a new large-format printer, as the custom filament would destroy the nose and feed path of the machines in our additive manufacturing facility.
Scientists want perfection, but the design and printing decisions made when producing these important components can have ramifications for the final product. Such as defects created when the printer stops and starts.
To ensure a seamless process, Joel and Rafael are using custom-built software that will print the collimator in 40 sections, minimising the risk of errors and breakages.
“Rafael’s expertise has been crucial throughout this process,” says Joel. “From making the filament to developing computer models to optimise the structural properties of the material.”
Joel and Rafael are also working on the production of gadolinium oxide filament, which cannot be found commercially, to produce test prints of a collimator for WISH-II, another instrument upgraded through ISIS’ Endeavour programme.
Not only that, the pair are prepared to develop custom filament and print bespoke, challenging components for any other customers. You can get in touch with them via our contact form.
Thank you to the UK International Science Partnership Fund’s ISIS-Diamond-PSI award for funding this project and Rafael’s joint doctoral fellowship with ISIS and PSI.
Written by Cat Lewin-Williams.
