3D printing is not the perfect tool for every usage and we are going to see through this article why you should use it or not and how 3D printing can be useful during crises through my experience with the Covid-19 lockdown in early 2020 in France. This article follows my introduction to 3D printing at home, feel free to read it if you want to learn more about the processes.

First large delivery of face shields to Strasbourg Hospitals, France, photo by Cristians Gonzalez

Why should you use 3D printing and why you shouldn’t

As we saw in the previous article, 3D printers are very versatile, you can print in one day, parts for a robot, then a ring, and finally a spare part for your bathroom by just changing the file on an SD card or USB stick. But this great flexibility also has some compromises, if you want to manufacture a part in large quantities or have your production certified, this method is not optimal. Printing a part takes a lot of time. A stack of 10 face shield like this one can take up to 11 hours to print :

Of course, this time can be reduced to a few hours on some machines by reducing the quality, but it will not be possible to approach the speed of a manufacturing process such as plastic injection for example, which can easily produce 2 face shields every 40 seconds or so:

Video shared on Linkedin by EURL BMI

A popular graph when talking about manufacturing processes shows how the different families of processes share the different needs according to the volume and variety of parts. 3D printers are found in the “Project” and “Jobbing” categories, while the injection is commonly found in the “Batch”, “Mass” and “Continuous” categories:

Figure from the publication [Walley P, 2003]

A wide variety of small-volume productions (prototyping or small productions) will require methods belonging to the “Project” and “Jobbing” groups, while high-volume and low-diversity productions will use “Mass” or “Continuous” manufacturing processes. We find the same observation when we qualitatively trace the cost of production as a function of the volume for these families:

A 3D printer costs almost nothing compared to a complete industrial production line when you want to produce a small quantity. But as soon as the volume increases, the cost per part increases linearly until one day the cost of a dedicated production line is crossed. From then on, 3D printing is more expensive and takes much more time.
That’s why 3D printers are usually found in innovation and prototyping environments where you want to test a lot of different things in small quantities and why you see very few of them on factory production lines.
But that doesn’t mean it will never be the case, technologies are evolving very rapidly and a growing attraction for customization of mass-produced goods could change the way things are manufactured. We saw the arrival of 3D printing at Nike, which offers to print parts of one of their custom-made shoes after using this process for many years in the design process of new products.

Their usefulness during a crisis, the Covid-19 example:

You may have seen it on TV or in the media all over the world since the beginning of the epidemic people with 3D printers (part of the “Makers” movement, you can also find under this name all people creating things themselves (DIY) usually as a hobby) have mobilized to help people without protection against the virus. I was part of a team named “Boucliers Fablab” (Shields Fab Lab in English) created by a surgeon of a Strasbourg hospital (France) during the Hacking COVID (a Hacking Health that started online on March 17th, I will come back in a future article on Hacking Health but in two words it is an event that brings together project leaders and volunteers to work on solutions to health-related problems).
The problem raised by the surgeon was the lack of personal protection equipment (PPE) for the medical staff in contact with patients. He was looking for a quick way to provide this equipment because the hospital could not get them through their usual suppliers. A multi-disciplinary team (ranging from 3D printing professionals to industrial companies, health care experts, nurses, surgeons, medical device designers, as well as human resources and marketing specialists) was quickly put together and we started looking for anti-projection protection solutions to complement surgical masks. Prusa’s Face Shield model had already been proven effective in various part of the world, so we made a few models and approached a supplier of transparent plexiglass plates for real-world testing and feedback.

First tests carried out at the CHU of Strasbourg, photo by Cristians Gonzalez

The week after having supplied about 50 face shields, we negotiated a price for the hospital from a 3D printing farm (a company that has many printers, the one we have contacted have 40) to manufacture in larger quantities (more than 1000/week) and in a controlled way (sterilization and packaging). Within 2 weeks the printer farm managed to cover the needs of 2 local hospitals with Prusa models and the link was created in case of future requests.

First large delivery of Face Shields to Strasbourg Hospital before assembly, photo by Cristians Gonzalez
Our strategy, at that time, was to 3D print the face shields until we could find a manufacturer capable of mass production with suitable equipment. 3D printers are not an adequate tool for mass production as we have seen previously. It is in this first phase of prototyping and testing that 3D printers are the most useful, to make a model and then have it tested in order to make adjustments according to the feedback. Then, we iterate until we get an optimal model. We were able to test a dozen models very quickly and could have provided a 3D blueprint validated by hospitals to industrial partners so that they didn’t need to do this time-consuming step.

Promising model designed by Alex Ta

After many iterations like the model above, it is finally the model below that was chosen, it meets all the criteria of the caregivers (sufficient thickness, good support without elastic, visor away from the face):

Final model designed by Alex Ta

This model was also created to be easy and quick to print (Prusa’s model took 3 hours compared to 1 hour for this model) and has the possibility to be stacked so that you don’t have to restart printing every hour:

Unfortunately, our discussions with several companies were not successful, but schools such as the University of Strasbourg or ENSMM (Besançon, France), for example, as well as manufacturers all over France (and around the world of course), were able to use their injection equipment to produce several thousand face shields (see the video at the beginning of the article).
At that time, the local supply was not yet sufficient to cover the many needs or did not meet the demand. With the help of many “Makers”/individuals, Fab Labs, companies, and communities who joined us in the adventure we, therefore, set out to provide the maximum number of hospitals and nursing homes in our area which also suffers from a lack of equipment. A partnership has been organized with the Post office, a room has been put at our disposal for quality control, sterilization and assembly carried out by volunteers. We were able to offer more than 6100 face shields to health professionals thanks to about thirty volunteers.

But this method had its limits, the printing time of one hour was far too long to provide the high demand that there was. The equipment wears out quickly, we all needed to repair our machines several times. For example, I had to replace the screw terminals that feed the motherboard and the heating plate (this happens when the screws loosen with the vibrations of the machine and an electric arc is created between the contacts):

What has been produced:

Here are some examples of things that can be printed with the 2 types of printers presented in the previous article, you can find more files on this site if you are interested.
Concerning FDM (Fused Filament Deposition), we saw mostly printing of visor supports and valves for decathlon masks or even door handles and masks. This method is perfect for large objects or objects in contact with the skin for example (PETG being one of the few 3D printed materials that can be brought into most hospitals for disinfection purposes).

Ear saver for surgical masks designed by Suraky

Door handle published by crashdebug

For printers using resin, some companies using surgical resins are able to manufacture swabs, rods inserted into the nose, for RT-PCR testing as formlabs do:

Photos from the website of Formlabs

For those who do not have access to these expensive resins, it is possible to print door handles, tools to help seamstresses make masks, or even visor clips for hard hats or caps:

These pieces are good for MSLA printing because you can put a lot of them on the board and thus reduce the printing time of each piece:

Formlabs, a manufacturer of high-end resin printers, has set up a platform that offers some files which they have been printing with resin since the beginning of the outbreaks, accompanied by a description of the pre-requisites for each object.

What happened next:

At the beginning of May, the governments intervene by regulating the production and distribution of these products, preventing anyone without certification from providing (selling or donating) this type of material, and then withdraws the text before amending it. Many groups are shutting down for fear of prosecution by a distributor coming on the market or by a user of the product. We have finished slowly providing the latest requests received, and with the help of lawyers, adapted our communication to comply with the regulations. This was a sign that a manufacturer was finally going to be able to supply the current demand at the national level and that our work on this was finally finished (we no longer manufacture any at the moment).
However, some groups of volunteers have transformed to meet the new requirements and are now working on new issues or exporting their production abroad.

Conclusions :

I am very pleased to have been able to participate in this initiative and to have met so many people dedicated to making this project work. We have seen the great strength of local movements that have been very responsive in the most affected areas. This decentralization was a major asset at the beginning of the epidemic, local networks were able to set up very quickly and organized themselves with local suppliers to avoid the disruptions due to the beginning of the coronavirus wave and the various organized lockdowns.
But we also see the limitations of 3D printing here, the regulation now imposes certification of face shields production, which is not easy with 3D printers and even less so when they are distributed in a network of fab labs and individuals who all have different machines and qualities.
Thank you very much for reading me,
See you soon!

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