Article 1 : 3D Printing

10 May 2020

We are pleased to unveil the first article of the MYE blog. We want to share with you information on domains or subjects linked to our project.

To begin, some history...

The first tests of 3D printing were made by Dr. Kodoma in 1980, who was the first to describe a method of layer-by-layer prototyping using a resin that solidifies when exposed to a UV lamp: this process is called Stereolithography (SLA). It was not until 1986 that Charles Hull, a French engineer, filed a patent for this technology.

At the same moment, an American researcher at the University of Texas named Carl Deckard is working on a new 3D printing method that allows local fusion of powder grains using a laser. He filed a patent in 1988 for this technology called Selective Laser Sintering or SLS (Slective Laser Sintering).

In the same time, Scott Crump was working on a third 3D printing method: fused deposition modelling (FDM). This process consists of melting a filament of material and depositing it layer by layer using a printing nozzle according to a previously defined pattern. Today, fused deposition has become the most popular printing method due to its simplicity but also due to the many advantages it offers.

Between 1980 and 1990, the three main methods of 3D printing were patented, which will mark the birth of this technology. But it was not until the 1990s that the first machines using the new CAD (Computer Aided Design) solutions were introduced.

The various 3D Printing techniques...

Stéreolithographie or stereolitograph apparatus (SLA) uses the principle of photopolymerization from a UV-sensitive resin. Indeed, the resin solidifies when passing a laser layer after layer to make 3D models. The steps of this manufacturing process are as follows :

- The laser beam scans the surface of the liquid resin according to the digital 3D model supplied to the printer.
- Once the first layer of material has solidified, the platform descends one level, corresponding to the thickness of a print layer, and a new section is then solidified.
- The process is repeated until the part is completed.

On some models of SLA machines, the production of the part is done in reverse. The platform is immersed in the resin tank after each layer is solidified while the laser works from the bottom up. Stereolithography technology is known for its quality but also for its superior surface rendering compared to other 3D printing methods.

Selective laser sintering uses the temperature generated by a CO2 laser to sinter powder and build layer by layer the 3D model. For this, the powder deposit must be heated above the melting temperature of the material. The manufacturing steps are as follows :

- A first layer of powder is deposited on the tray
- It is scanned by the CO2 laser to cause sintering and consolidation of the powder
- When the layer is produced in this way, the tray is automatically lowered and the steps are repeated to obtain the desired part layer by layer

This technology enables the manufacture of parts in a wide range of materials such as plastic polymers (Polyamide PA12, Nylon, PEBA, high performance thermoplastic (PEEK)), carbon, glass and aluminium fibres. The use of fibres allows to exponentially improve the mechanical behaviour of the parts.

Fused Deposition Modeling is considered to be the simplest 3D printing method. Indeed, this technology is based on 3 main elements :

- A printing plate on which the part is printed
- A filament spool for use as printing material
- An extrusion head also called an extruder

To produce a part in 3D printing, the filament is driven and melted by the extruder according to the previously defined pattern. The extruder deposits the melted material layer by layer on the platen. The platform descends one level with each new layer applied, until the object is printed. In the field of 3D printing, the deposition of molten wire is a fairly widespread and well-known technology. Indeed, this technology has the advantage of being able to be used for a wide range of materials, the only condition is the temperature heating the extruder :
- Thermoplastic materials (PLA and ABS, but also Polycarbonate, PET, PS, ASA, PVA, Nylon, ULTEM)
- Composite materials based on metal, stone and wood
- Ceramic material or even clay by replacing the extruder with a syringe

Moreover, this technology also allows the construction of parts with several coils and therefore several colours. These parts thus built are called polychromatic.

3D Printing today :

As far as 3D printing is concerned, several companies have taken the lead by sharing the juicy market of this technology :

- EOS GmbH developed the first EOS "Stereos" system for the industrial-scale production of parts in high-quality 3D printing. Today, the company is world-renowned for its use of selective laser sintering (SLS) technology for plastics and metals.
- The Stratasys company developed by Scott Crump is also a reference in this field. Since its creation, it develops 3D printers for professional but also individual use allowing a popularization of this technology and an access to all.
- Zcorp emerged in the 2000s and quickly established itself as a leader in the industry by offering ink-jet printing technology (from MIT), which produces models using previously unseen materials such as starch or gypsum powder-based materials, or a water-based binder

But then if this technology was already known at the time, why has a subject like this become such a popular and fashionable topic nowadays ? Quite simply because this year marks the expiry of the various patents previously filed and opens the door to the first low-cost 3D printing : what used to cost $200,000 has suddenly become available for less than $2,000. Moreover, starting in 2009, this technology is gaining in popularity but also in media visibility with the first 3D printed organs and the many innovative prostheses created with this technology. This revival in the medical sector opens up the field of possibilities, allowing more people to become familiar with this technology.

Today, 3D printers are constantly improving both in terms of technology and materials used. 3D printing has not yet reached its limits, and now affects professionals and private individuals in all fields.

A focus on how we applied 3D Printing in our project

What link exists between 3D Printing and MYE ?
It is simple !

During our respective engineering trainings, we were brought to handle the different CAD software and we learned that making a product in the classical way in industry is quite expensive if it is not made in large quantities.

After the first phases of digital prototyping, we quickly came to the conclusion that if we wanted to make a physical prototype at a lower cost, we had to look into 3D printing. Having modeled parts that were not on the market and required precise dimensions and characteristics, we needed the freedom and efficiency of 3D printing.

After several tests, we were able to print the parts of our first prototype. Since FDM printing is the most widely available to the general public, we were able to call upon a knowledgeable person with a 3D printer of this type and obtain our parts quickly and at a lower cost than if we had gone through professionals. The parts were made in PLA because, on the one hand, the constraints encountered by our system are low from a mechanical and thermal point of view, but also because this material does the job for a proof of concept.

Result : the parts of our prototype were printed in just 2 days and for a budget of 5€. Winning combo for the MYE team ! You can admire the rendering on the following images :

Source :
https://www.3dnatives.com/frittage-selectif-par-laser/
http://prismadd.com/technologie-sls/
https://www.sculpteo.com/fr/centre-apprentissage/technologies-impression-3d/fdm-vs-sla-vs-sls-vs-dls-affrontement-des-technologies/
https://rocbor.net/Product/Ressources/NouvellesTechnologies/StereolithographieAndCo/Processes/SLA.htm

Website online !

You can find out the Team presentation, last news and all the Newsletter we have written.