Guide to Stereolithography (SLA) 3D Printing

You know what 3D printing is. Were you aware that there are multiple types of this technology? Stereolithography is a method that can deliver impressive accuracy. You need the best resin 3D printer to use SLA to the fullest. Before looking for a suitable model, this guide will help to learn more about this stereolithography. Keep reading to discover all SLA basics!

What is Stereolithography 3D Printing?

3D printing technology uses additive manufacturing. It involves inserting layers until you get the final product. The SLA method refers to vat polymerization, which requires a resin 3D printer. You’ll find three different approaches in this category:

  • DLP – Digital Light Processing. It involves getting UV light from a digital projector to create layers.
  • LCD – Liquid Crystal Display. This module type serves to deliver the desired light patterns.
  • SLA – Stereolithography. Light sources are UV lasers, which serve to make polymer resins.


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When and Where Did Stereolithography Originate?

The history of SLA goes back to the 1970s. It originated in Japan, where Dr. Hideo Kodama first used UV light to cure polymers responsive to it. Charles W. Hull patented the term stereolithography in 1986. The technology was expensive at the time. Fused filament fabrication (FDM) machines took the market, but they couldn’t deliver that precision level. Today, SLA is more accessible and affordable. You can apply it across many niches, and it’s suitable for at-home use.

SLA Printing Process

The basic workflow of an SLA printer isn’t much different than other 3D devices. It involves three steps:

1. Design. You need specialized software to create a model to print. The experts recommend CAD tools. Many manufacturers deliver software with the product. You need the final file to be in OBJ or STL format.


Design - Cad Software for 3D printing


2. Print. It’s necessary to set optimal adjustments on your printer. Once you have everything ready, the machine can work even if you aren’t there. Some devices have cartridges that automatically refill the material when needed.


Print - 3D printer


3. Post-printing. You’ll need IPA (isopropyl alcohol). Use it to rinse the components. The goal is to clean any uncured resin. Let the parts dry and start post-curing if necessary. It can help to strengthen and stabilize the components. You can sand the support marks to ensure smooth finishing.


Post-processing - 3D printing

How Does Stereolithography Work?

SLA technology has many specifics in the printing process. Here is a brief explanation of how everything works:

1. You need to place the build platform in the liquid photopolymer tank. The distance should be a single layer height from the liquid’s surface.

2. The laser will cure and solidify the resin to make the next layer. Now, the liquid resin contains monomer carbon chains. The UV laser uses light to activate and solidify them. It strengthens the bonds between the chains and makes them unbreakable.

3. There’s a path that the laser beam follows. Specialized mirrors or galvos create this path. They scan the entire model area, which results in a solid part.

4. Once you finish, you should treat its part. The exact moves depend on the component.

If you make a part in an SLA 3D printer, it’s impossible to reverse the process. A solid component can’t become liquid again. If you heat them, they will burn.

Main Parameters of the Best Resin 3D Printer

While choosing the device, you need to consider its parameters. Layer height can vary from 25 to 100 microns. If you pick a lower option, it can record curved shapes with more accuracy. However, it increases build cost and printing time. The results might not be in line with your expectations. Unless you are an advanced professional, go with a 100-micron option.

You’ll find two main build orientations in SLA 3D printers:

  • Top-down. These are industrial units with huge build sizes. They cost more and a professional needs to operate them. This device has a tank below the laser source.
  • Bottom-up. It’s a more common option. Manufacturers put the light source beneath the tank. The silicone coating at the bottom is transparent, and the UV laser passes. Bottom-up printers are more affordable. Also, they have a smaller build size and material range.

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Different SLA Printing Materials

Liquid resins are the components of this process. Different characteristics are available, ranging from abrasion to thermal resistance. Check out the common options:

  • Standard. The resin is affordable, but it’s also quite brittle.
  • Clear. If you need transparent material, go with this option. It requires a demanding post-processing procedure.
  • Castable. This resin serves for molds since it has a low ash percentage.
  • Dental. It’s more expensive, but it’s biocompatible. The material has excellent abrasion resistance.
  • Flexible. These resins are like rubber, but their dimensional accuracy is low.
  • Durable or HT resins. A tough material has impressive mechanical properties but low-temperature resistance. You can also pick HT resins. These resist high temperatures, which makes them versatile. 

Main SLA 3D Printing Characteristics

Everything about Stereolithography SLA 3D Printing in 2021


You need an adequate support structure. You use the same material to print them as for the component. Once the process finishes, you remove the support structure. The requirements depend on the printer type. Support structures are complex for bottom-up devices. Their accurate construction is imperative for optimal results.

If you want part precision, take care of the curling process. As the light gets on the part, it will shrink. If it’s beyond expectations, problems could occur when adding a new layer. You can place additional support in risky areas to reduce the curling risk. Additionally, avoid over-curing a particular component.

The typical build size for desktop 3D printers is 145 x 145 x 175mm. This increases to 1500 x 750 x 500 in industrial devices. You’ll find the common layer thickness to be from 25-100µm in both types. Depending on the design, these devices can deliver a smooth finish and impressive precision. 


You can also check our article on Types of 3D Printing Explained.

Final Thoughts

If you want maximum results from SLA, you need the best resin 3D printer. You can check online stores and pick a model that suits your needs. If it’s enough, go with an affordable in-home unit. Alternatively, choose a bigger printer that delivers highly professional results. You should pick based on your expectations and budget. That will ensure you find a 3D printer that best suits your needs!