To help with ongoing personal protective equipment (PPE) shortages, Ontario-based nanofibre manufacturer, BIG-nano
, has collaborated with Renishaw
to create a local supply chain for protective masks using additive manufacturing (AM). BIG-nano developed a ‘fine liquid blowing technique’ for the production of nanofibre, allowing it to more easily scale production at affordable costs.
Renishaw used one of its RenAM 500Q systems located in Canada to build a ‘novel’ titanium nozzle for the liquid blowing process; it can produce ‘N99 quality’ fabric, while reducing maintenance costs and downtime.
In 2018, BIG-nano developed a novel gas-assisted jetting process to manufacture nanofibres — polymer fibres with diameters in the nanometre range. Its technique streams high-velocity gas through a needle, while a polymer liquid solution is simultaneously accelerated to the tip of the same nozzle. The two streams interact, bringing the polymer from molten to fibre state and producing a poly (vinyl alcohol) non-woven fibre mat.
Nanofibres are steadily gaining popularity in drug delivery systems, medical implant devices, water and air filtration, and protective clothing applications. After Covid-19 caused a shortage in PPE for healthcare workers, BIG-nano saw an opportunity to contribute.
N95 and N99 masks are produced using a fine mesh of polymer fibres to filter particles and are regarded as the gold standard for healthcare workers and other medical first responders. To meet the standard, these face coverings must ensure a 95/99% filtering of airborne particles, protecting users from Covid-19. Nanofibres are particularly effective at achieving a high percentage of particle filtration.
John Rawlins, co-founder of BIG-nano, said: “The Coronavirus pandemic demonstrated to nations world-wide that some products like PPE should be manufactured locally for the national interest. Supply chains around the world broke down in a way that no one anticipated. The call by the Canadian government to work on PPE locally in a way that is secure for our communities interested us. It was something immediate and good that we could do, so we stepped up to that challenge.
"The nozzle consists of a compressor system that heats the air, and an extruder that melts the polymer. That polymer is then brought into the extruder to meet the heated gas. The nozzle does the work of processing the polymer from molten to fibre state, it really is the heart of the whole system.
“We realised machining the nozzle for our jetting process would mean we couldn’t complete the project in time, so we looked to additive manufacturing for a solution. Renishaw brought valuable additive manufacturing expertise we didn’t have in-house, giving us the ability to produce prototypes for a new nozzle design quickly, despite their complexity.”
Renishaw and BIG-nano are still collaborating to perfect the system. The team’s goal is to make the nozzle larger to increase nanofibre throughput and allow larger volumes of mask production.