Trying to learn more about 3D printing? SLA, also known as stereolithography, is an additive of the manufacturing process, and they create SLA when they cure the polymer resin layer by layer with an ultraviolet laser beam. The 3D printing material that they use to make SLA will have photosensitive thermoset polymers. It comes out as a liquid form. In general, people choose the SLA form because of how it remains one of the most cost-effective measures that you can take.
How It Works—Step #1: Getting Started
Before it begins, they will first position the platform and the tank of the liquid with the SLA resin. People will see it at one layer height for the surface of the liquid. In general, they will get the best results when they take advantage of the limitations and benefits of the process.
Step #2: The Laser Begins the Next Layer
In the next step with 3D printing material, the laser will cure and solidify the photopolymer resin. Through the 3D printing technology, it will focus the laser down a specified path, and it will use a mirror known as a galvos. The mirror can twist quickly and accurately to steer it into a specific pattern.
Step #3: Sweeper Blade
Once the laser has finished with recoating the surface, you have what is known as a sweeper blade. This will add another coating to it. As this happens, the process will continue over and over until you have finished with it.
Step #4: Finishing Up
When the printing ends, the print will be in an unfinished and green state. A fully cured state doesn’t exist. It will get processed under a UV light, and it will have a high mechanical and thermal process that will begin it. This helps to bring everything back together.
Most Common SLA Materials
When it comes to some of the most common SLA materials, people have a few that they may want to keep in mind that include: Standard resin; Clear resin; Heat resistant resin; Rubber-like resin; Ceramic-filled resin; Tough resin.
The standard resin has the characteristics of high hardness, high resolution, and smooth model surface. And the low cost of standard resin makes it an ideal choice for printing materials. You need to be aware that the color of the resin affects its performance. For example, if you print parts with fine details, the gray resin is more suitable. If you print parts with a very smooth surface, the white resin is the best choice.
The advantages of the standard resin include fine model, smooth surface, most economical, and practical material. The disadvantages of the standard resin include low elongation at break and low impact strength.
The standard resin is more suitable for concept modeling, rapid prototyping, and art models.
The clear resin has the same characteristics as standard resin. However, the difference is about the post-process that wet sanding is needed to achieve the smoothest surface finish.
The advantages of the standard resin include smooth surface and most economical material. The disadvantages of the standard resin include low elongation at break and low impact strength.
The clear resin is more suitable for showcasing internal features, LEDs housing, and fluidic devices.
Heat Resistant Resin
Heat resistant resin is one of the most ideal material options, but it needs to be high thermal stability and high-temperature printing. The hot deformation temperature of these resins is between 200-300℃. If you want to make heat-resistant clamps, mold prototypes, hot air, and fluid flow equipment, as well as casting and hot forming molds, heat resistant resin is the best choice.
The advantages of heat resistant resin include high heat deflection temperature and smooth surface. The disadvantages of heat resistant resin are low elongation at break and not suitable for thin parts.
The heat resistant resin works especially well with visual applications or where people will need a high level of detail. The one downside of this resin is that people might still see the support marks on it. Heat resistant resin is more suitable for mold prototyping, casting, and thermoforming tooling.
For rubber-like resin, engineers can simulate rubber parts with soft to touch. This material has a low tensile modulus and high elongation at break, and it is more suitable for objects that will be bent or compressed.
It can also be used to add ergonomic features to multi-material assemblies, like packagings, stamps, wearable prototyping, handles, over molds, and grips.
The advantages include high flexibility, low hardness, and high impact resistance. The disadvantages include the lack of the properties of true rubber, the requirement of the support structure, and not suitable for thin parts.
Rubber-like resin is more suitable for wearables prototyping, multi-material assemblies, handles, grips, and over molds.
Reinforced with glass or other ceramic particles, rigid resins can print very stiff and rigid parts with a very smooth surface finish. Rigid resins have good thermal stability and heat resistance. They have a high modulus of elasticity and lower creep. Compared to other SLA resins, it’s more brittle than the tough and durable resin.
The advantages of the ceramic-filled resin include high stiffness, suiting for parts with fine features, and moderate heat resistance. The disadvantages include low elongation at break and low impact strength.
Ceramic-filled resin is more suitable for molds and tooling, jigs, manifolds, fixtures, housings for electrical and automotive applications.
It belongs to hard resin, which can bear high stress and strain. Its tensile strength and elastic modulus are the same as ABS. The model printed with this material is stronger and more stable.
This material can be used to produce sturdy, shatter-resistant parts and functional prototypes, such as housings with bayonet joints or robust prototypes.
The advantages of tough resin are high hardness and excellent resistance to cyclic loads. The disadvantages of tough resin is low heat deflection temperature and low elongation at break.
The tough resin is more suitable for functional prototypes and mechanical assemblies.
Choosing the right resin for the application becomes critical. To get the right 3D printing material, consider the mechanical properties of the printing material, and make sure it matches the needs of the project.
Benefits & Limitations of SLA
With SLA, people have a relatively fast production. In addition, when it comes to scalability, they can do it easily, and they don’t have to worry too much about wasted materials. For a good complex model, SLA works great because of how it has been built to handle these types of applications.
Where does SLA fall short? People do have a few drawbacks that they may want to understand before undertaking the project. For example, some parts will be more easily affects by moisture. The layers might also cause a type of stair-stepping instead of a smooth surface.
Rules of Thumb
In general, an individual may want to use SLA if they plan to produce a visual prototype of the image. In addition, keep in mind that SLA parts will usually have poor mechanical properties that make it perfect for non-functional prototypes. When you go to choose an SLA, think of the application that you will use it for. For example, when you need heat resistance, you might choose the resin with higher heat resistance. Castable resins don’t leave much for residue, and they won’t have burnout ash with it. There’s very little waste, which is what has drawn many people to using SLA for 3D printing projects.
Current Situation and Development
In recent years, SLA has gotten more affordable because, in the past, the cost made it virtually unavailable to all except the big corporations. However, it has become a material that all 3D printer specialists can use now if they desire, but an individual should understand the applications of it first. In terms of development, it is likely that the costs for this material will continue to drop in the foreseeable future. Along with that, the development of it will mean that people can do more and more things with this material to make it even more valuable. As 3D printing continues to advance, it is likely that the practical uses for this material will advance as well.