The respirator, which can be made using specific types of 3D printers and fulfils the highest-level protection criteria, was developed by the Czech Institute of Informatics, Robotics and Cybernetics (CIIRC) of the Czech Technical University (CTU). The reusable respirator helps protect the wearer against infection by the new coronavirus and is mainly intended for doctors and other front-line staff. The entire process, from the start of development to the certification of the respirator and getting production up and running, took just a week.

The reusable respirator helps protect the wearer against infection by the new coronavirus and is mainly intended for doctors and other front-line staff.
Photo: CTU

Any company that owns one of the three types of Multi Jet Fusion 3D printer can now take part in producing the CIIRC RP95-3D respirators. They just need to contact the specialists at the Czech Technical University. As ŠKODA owns one of the limited number of printers of this type in the Czech Republic, it moved swiftly to get involved.

This printing method ensures you get a homogeneous material that does not have distinct layers and is not porous.
Photo: Michal Čížek

David Vaněk
head of the prototype and model construction department at ŠKODA

Vaněk and his colleagues prepared for respirator production by making a series of five test prototypes. Then a larger series of respirators was printed, and after the process as a whole was gradually optimized, the ŠKODA 3D printer can now print 60 units in a single batch. “Everything was fine-tuned so that the respirators in a print batch were as close as possible without affecting each other so that the printing process was as efficient as possible,” says Martin Sova, coordinator of plastics production and the 3D printing competence centre in the prototype construction department.

Removing excess powder from the printed respirator mask.
Photo: Michal Čížek

Printing one batch takes sixteen hours, followed by a cooling phase that takes roughly the same amount of time. The entire production process is optimised so that the same respirator parts are created wherever they are printed. “This repeatability is extremely important for certification, as only a mask made in this way qualifies,” says Martin Sova, explaining why professional machines have to be used and respirators can’t simply be made using home printers.

The next goal is to start mass-producing respirators.
Photo: Michal Čížek

So instead of parts for test prototypes, the EGV department now turns out 60 full respirator sets a day. The printed sets consist of four parts: the main masks, seal caps, the filter cartridge attachment adapter and exhalation covers. The parts are dispatched to the firm 3Dees, which collects components from all the suppliers and takes care of the final assembly. The finished respirators, which can be used and disinfected repeatedly and whose filters remain functional for up to a week, are then sent to the health ministry, which manages their distribution to the places of greatest need.

The printer prints the respirators in layers.

Layer upon layer

The production process takes over ten hours because the respirators are printed in layers, as the polyamide powder is fused by infrared light. In the first step, a layer of powder is spread across the work bed. “Then the print head sweeps across the layer, emitting two substances that basically draw the next layer of the finished part. Then an infrared heater sweeps across it. The powder reacts with the substances to create a solid material,” Martin Sova explains the printing process. In the next step, the work bed moves down in the print box by the thickness of one layer, and this is repeated over and over again.

After completion, the printed set must be allowed to cool, as the infrared light fusion temperature can reach 180 degrees Celsius. The build box is kept carefully sealed so that the powder cannot escape during printing and the finished parts do not move, which would spoil the printing process. That’s one reason why this large print set takes a long time to cool. Even so, this is by far the most efficient 3D printing production method, according to both Martin Sova and David Vaněk.

The respirator, which can be made using specific types of 3D printers and fulfils the highest-level protection criteria.
Photo: Michal Čížek

The next goal is to start mass-producing respirators. But that will require plastic injection moulds, which take several weeks to prepare. That’s why the 3D printing method is currently the best option for providing respirators quickly, at least for the most critical requirements.

“We will keep supplying our 60 respirator sets a day for as long as they’re needed,” says David Vaněk. Only when the situation allows will the 3D printer revert to its usual job of producing parts for ŠKODA.