What is SLA 3D printing?

Laser stereolithography, also known as SLA 3D printing, is not only one of the first 3D technologies in the world, but also one of the most accurate additive manufacturing techniques. In a way, it is unique because it uses liquid photopolymer resin as a consumable material. The essence of the technology lies in exposing the photopolymer to light according to a specific algorithm (set by a slicer program based on a 3D model). Under the influence of laser radiation, the resin hardens, forming the finished object.


SLA 3D printing on a 3D printer


As with FDM 3D printing, SLA 3D printing requires the construction of support structures in parallel with the construction of the object if there are overhanging elements in the model. In essence, this technique is similar to SLS 3D printing, but instead of powder, a liquid photopolymer is used. Otherwise, it is the same layer-by-layer reproduction of products based on specified 3D models. We will discuss how SLA 3D printing works in more detail below.


Features of operation

In order to understand how the 3D printing process works, it is necessary to understand how an SLA 3D printer is designed. The image below, which shows a diagram of a classic stereolithography printer, will help you with this. We say classic because this is the patented SLA printing technology. This design is also used in industrial devices for SLA 3D printing. As for the desktop SLA 3D printers that are already in use, they use what is known as “upside-down SLA 3D printing.” What does this mean?


SLA 3D printing


First, let's describe the printing process in the image above. In it, the laser is located at the top, and the working platform gradually descends. So, a mesh platform is immersed in a container with photopolymer to a depth of no more than 0.05-0.13 mm (this is the thickness of the layer). Then the laser is activated, affecting certain areas of the material (specified by the program). The laser radiation causes the first layer of photopolymer to harden. Next, the platform descends another layer lower, the laser is activated again, continuing to form the object, and so on until the final construction of the product.


3D printing SLA principle


As for the 3D printing process used in desktop 3D printers, the principle is exactly the same. The only difference is that the laser is located under the photopolymer container, and when constructing the product, the platform does not descend, but gradually rises upward. Common to both options is the washing of the product in special solutions after completion of 3D printing, as well as the irradiation of the finished model with ultraviolet light. The first is necessary for the final cleaning of the product from photopolymer residues, and the second for the complete curing of the product.


Differences from DLP 3D printing

Several other techniques have been developed based on SLA 3D printing, one of which is DLP 3D printing. Since the latter has gained considerable popularity, we thought it would be useful to say a few words about it. There is no fundamental difference between these techniques, but some differences should be mentioned. So, how does SLA 3D printing differ from DLP 3D printing? It's very simple: instead of a laser, DLP 3D printers use a projector that illuminates an entire layer at once, rather than gradually, as a laser does in stereolithography.


3D printing SLA Kiev


It is believed that this allows DLP printing to reproduce objects slightly faster. However, this difference is not significant enough to displace stereolithography printers from the 3D printing market. In addition, DLP 3D printers use photopolymer resins with a different exposure wavelength, and the quality of 3D printing on some models is inferior to that of SLA printers. But, again, there are no significant differences between the technologies.


Materials used

As we mentioned above, 3D printers that use laser stereolithography technology use liquid photopolymer resins, also known as photopolymers. These are special substances that change their properties when exposed to light. Most often, the active radiation is ultraviolet. Dentists are familiar with the term “photopolymer,” as similar substances are widely used in dental practice. In essence, this is a case where one thing has several different applications.


3D printing SLA photopolymer


What photopolymers does SLA 3D printing use? A wide variety. Even on the desktop 3D printer market today, you can find flexible and rigid, engineering and decorative, dental and burnable photopolymer resins in all colors and shades. Of course, the range is not yet as wide as, for example, in FDM 3D printing, but it is SLA 3D printing and its consumables that are second in popularity among users.


SLA 3D printing: advantages and areas of application

Let's start with the advantages that SLA 3D printing offers users. We will touch on both industrial and desktop devices for reproducing objects. So, here are the advantages of the technique:

  • High-precision 3D printing;
  • Manufacturing of products of any complexity;
  • A large selection of different materials;
  • The ability to manufacture ready-to-use products;
  • Low material consumption for support structures.


Now let's describe the areas of application of the technique:

  • Jewelry;
  • Dentistry;
  • Design;
  • Modeling;
  • Prototyping;
  • Manufacturing of models for die casting.

And in general, anywhere where high-quality reproduction of 3D models is required, because it is SLA 3D printing that allows you to obtain extremely detailed products, even of tiny sizes. And thanks to the availability of burnable photopolymers on the market, the possibility of casting from printed models is greatly simplified.


Equipment

To learn more about the 3D printers used in this printing technology, take a look at our “SLA 3D Printers” section, where you will find a wide range of equipment in this category. In particular, we offer the following devices:

  • Form 4 from Formlabs;
  • KLD 3D printers in assortment;
  • Wanhao SLA 3D printers;
  • LiquidCrystal 3D printers;
  • B9Creator and many others.


For detailed information about this and other equipment, please contact us by phone or email listed in the “Contacts” section. We look forward to working with you!