Resin: 3d printing simple & helpful explanation
3D printing with resin is based on stereolithography (SLA) or VAT polymerization technology which is the most well-known 3D printing method to produce high quality and high detailed models. The purpose of this article is to touch the basics and help our readers understand what is this technology all about and the applications of resins.
What is common ground of the resin 3D printing across the board of the different technologies (SLA, LFS, DLP, LED or LCD) is that they use photopolymerization to create objects. The printing process of resin 3D printers – is not the same as filament-based printers – they use a computer controlled UV (Ultraviolet) light source and operate based on a code. The light wave forms a pattern/outline of a single layer in the resin converting it to a solid model. Then the platform moves again to allow the liquid resin to come through and form a new layer above the plate. The material is stored into a resin tank called vat. Those phases will be repeated until the final 3D model is complete.
What is polymerization
Polymerization is the chemical reaction that describes the transformation of a liquid status material to solid under the effect of an ultraviolet light source. Such liquids known as photopolymers they are called resins.
Resins categories
There are six main categories of resins:
⦁ Standard
That covers the general type of resins used for most applications.
⦁ Castable resins
Those are suitable for metal parts especially in the jewellery field as it is possible to print extremely high detail resulting in high precision jewel items.
Castable Resin Jewellery
⦁ Clear resins
This is a special type of resin that has a clear glass finish in it. The clear resin when polished thoroughly can reach an excellent transparency level.
⦁ High temperature resins
These resins have high heat resistant properties which makes them suitable for environmental applications. Some resins can withstand temperatures up to 280oC.
⦁ Durable resins
These are ideal for applications in the manufacturing industry, able to withstand high stress and wear.
⦁ Dental resins
With such resins professionals in dental industry can achieve high detail and precision to their dental objects. Examples are the retainers that require strength and high durability in orthodontic treatment.
What are the advantages of resin 3d printing?
⦁ Greater object resolution
Compared to filaments, resin based 3d printing will result much better detail on the printed model. Due to the fact that photopolymers are actually liquids, it is much easier to achieve any shape and complex geometry needs to be produced.
⦁ Faster 3D printing process
In terms of printing speed, resin is much faster. It is worth mentioning that DLP technology is even quicker as in each pass, a full solid layer can be formed.
⦁ Better surface finish
On a resin 3d printed object the layer lines are much smaller compared to other technologies (FDM etc)
⦁ Better final product
During resin printing, each laid layer is bound with the next one resulting a much stronger object. The printed model will have better and uniformed mechanical properties across it’s structure while a filament printed model is weak against shear forces due to the poor cohesion between the layers.
⦁ Big variety of materials
As we saw above the variety of resin types is adequate enough to cover all the user needs and applications.
⦁ Waterproof 3D models
This is one of the biggest advantages in comparison to powder based on technologies. The 3d resin printed product is waterproof and it does not absorb any moisture from the environment.
What are the disadvantages of resin 3d printing?
⦁ Cost and running costs
While you can go out and buy an FDM with £250-300 and produce descent models, you will need at least x3 times that to approach the cheapest range of resin 3d printers.
With respect to running costs, the purchase of a filament is a fraction of the cost of the resin one. Also, each time you go ahead to print something with the resin-based printer, you will need to make sure that the vat is fully loaded with resin.
⦁ Time consuming post processing
During that phase the model supports need to be removed and the model needs to be sanded carefully in order to remove surface distortions and/or to be subsequently polished.
⦁ Design limitations
Crucial is the orientation of the part in order to achieve the highest level of detail. Also, model meshing knowledge is required to ensure a consistent and smooth model surface.
In conclusion
Resin method might not be the first option for large scale objects however, when a complex geometry with high level of detail and accuracy is needed, resin becomes the obvious choice. As we discussed in this blog, the application of resin material in 3d printing has significant advantages against the filament-based printing methods. When model detail and mechanical properties (isotropy) are top in the agenda then, resin 3d printing is the only choice regardless of the still significant drawback of cost.
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