If you are new to SLA you may have heard the SLA abbreviation and wondered what it meant. It stands for stereolithography, which is one of the oldest printing methods that is still used today.
In this article we will be delving into the SLA world and discovering what does SLA stand for in 3D printing.
History of SLA
LA stands for stereolithography. This was first introduced in the early 1980s when Hideo Kodma first used ultraviolet light to cure photosensitive polymers. The term was then coined by Charles W Hull in 1984. In 1986, Hull co-founded 3D systems to commercialize the technology.
Therefore to begin with, stereolithography was used in industrial settings only. Hull said that the method of stereolithography was creating 3D objects by printing thin layers of materials that are curable by ultraviolet light.
Although today, SLA is used by both industrial and desktop printers, and is seen as a very popular method of printing to use. You can see this application used mostly with the dental and jewellery industries, product design and manufacturing industries.
What is SLA Printing?
Stereolithography belongs to the resin 3D printing family. A SLA 3D printer uses light reactive materials known as resin. When SLA resins come into contact with certain wavelengths of light, this then causes short molecular chains to join together.
SLA parts that you have printed have some of the highest accuracy and resolution. SLA will give you sharp details and one of the smoothest finishes possibly of any 3D printing technology. However, the reason why people use stereolithography is because it is so versatile.
The UV light bonds all the layers of the product together, in a process called photopolymerization. After all the layers have been bonded together, they can’t be separated, and if you apply heat to the layers the entire product will burn.
What Happens During SLA Printing?
The building platform is submerged into a tank that contains some kind of liquid photopolymer, this will most likely be liquid resin. The platform is sunk one height layer away from the surface.
Then, a UV laser is used to create layers. This happens through selective curing and solidifying of the resin. After every layer is complete, the platform is moved away from the laser.
A sweeper blade comes in and recoats the layer’s surface. This process repeats until the product is complete.
After the product is complete, a post printing process is normally applied to create the desired finish that is required.
Common SLA Materials
Normally, SLA appears in the form of a liquid resin. It is known that resin can be quite brittle, therefore SLA parts aren’t suitable for any form of heavy pressure or impact. The following are some of the most used resins used for SLA 3D printing.
- Standard resin – This provides your printed parts with a smooth finish, but it is one of the more brittle resins to be using.
- Clear resin – This is a very transparent material, but post-processing application is required to get a very clear finish.
- Castable resin – This is used for creating mold patterned.
- Dental resin – This is one of the more costly resins, but it is biocompatible and very highly abrasion resistant.
- High temperature resin – This resin can handle extremely high temperatures and is used for injection molding.
Characteristics for SLA 3D Printing
There are two types of SLA printers, these are desktop and industrial. An industrial SLA printer uses a top down approach, this is where the laser is placed above the tank. While a desktop SLA printer is the other way around, and the laser is beneath the tank.
Industrial SLA printers are much bigger than desktop printers. As a result, they work a lot faster and can print much bigger parts. However, due to their size they are a lot more expensive to maintain and more difficult to operate. Their minimal layer height is 25 microns, while their maximum is 150 microns.
While, desktop SLA printers are much smaller and lighter, they are only used for printing small parts only. Due to their size they are a lot less expensive and much easier to use. The minimal layer height is 25 microns, while the maximum layer height is 100 microns.
Depending on the type of resin that you use, there will be some kind of after printing technique used to improve the finish and quality of the product.
Some common techniques that are used after printing includes polishing, sanding, mineral oil finishing, spray coating and UV treatment. This does depend on the product you have printed and the resin that you have used to make said product.
SLA 3D printing is used across a wide range of industries and businesses. This process has been used in the following industries:
- Manufacturing – SLA is used with product designs for new parts. It is used to create realistic proofs and to help advance new ideas through each stage of the manufacturing process until it is ready to be produced properly on a mass scale.
- Dental – This process helps create high quality dental products and appliances at a much lower cost with a perfect fit. As SLA is so accurate, better fitting products can be created.
- Education – Like any 3D printing process, students can learn about this process in school and use it themselves for other subjects like science or art.
- Healthcare – Like with dentistry, SLA 3D printing can be used to create more customized products for each individual for the treatment they are having. It is a cost effective way and saves everyone a lot of time.
- Entertainment – 3D printed parts have been used in many stop motion films. They can also be used as special effects or in video games.
SLA is known as stereolithography and is one of the oldest and prominent 3D printing methods that you will see being used today. It can create a wide range of products across many different industries.
Products made from SLA are mainly used as prototypes, due to being very brittle. However, this printing process has been loved for many years and will continue to be used for many years afterwards.
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