What is Stereolithography?

April 7, 2021
Stereolithography SLA 3D Printing

There are several methods that are used to create 3D-printed objects. One of those ways is called stereolithography. This process used a 3D printing machine called a stereolithograph apparatus or SLA for short. It converts liquid plastics into solid objects and was patented as a means of rapid prototyping in 1986 by a man named Charles Hull who was the co-founder of 3D Systems, Inc, making it the first 3D printer ever built.

While the process is very simple, the results of stereolithography are limitless. SLA has become popular after the introduction of desktop SLA 3D printers. It was before this that stereolithography was strictly restricted to commercial or industrial use. Now, SLA can be utilized by anyone for whatever their 3D printing needs are.

What Is the Process of Stereolithography?

The process of SLA is as follows:

  • A clear or opaque liquid photopolymer resin fills a tank and is ready to be cured. 

  • A perforated platform is immersed inside the tank which contains the resin. This platform moves up and down a fraction of an inch to control the z height (layers) of the part.

  • A powerful UV light or laser selectively hardens cross sections of material on each layer 

  • The platform lowers to the next layer to repeat the process.

  • The platform is removed from the tank and the uncured liquid resin is washed off leaving a solid part and it’s support material that holds the part during printing.

  • The support material is removed by hand and the part is post cured with ambient light or a UV oven.

  • The surfaces where the support material touched are cleaned up by hand, usually with sand paper or other finish instruments. The part is now complete.

The Working of SLA Printers

The workings of SLA printers is the one that every printer shares. 

  • First you need a 3D model, or CAD (computer aided design) model. 3D designs are created with the help of CAD software. Most printers require an STL (surface tessellation) file to print the object. The vast majority of CAD software can export STL files.

  • These files are then processed through the 3D printer software. This software cuts up the model into layers and selectively adds support material so the model does not collapse under it’s own weight from gravity. Most SLA printers print upside down. The software will also control the print speed and cure time. Depending on the resin you are using, different speeds and amounts of UV exposure are required to get a fully cured and mechanically stable part.

  • After each layer is complete, the final step is to cure the object inside of an UV oven, or by allowing the part to sit in ambient light for several days. This is to increase the strength of the 3D model. A part cured in ambient light will generally not reach the mechanical properties of a part cured in a UV oven, but for prototyping and modelling purposes it can still be sufficient.

Why Choose SLA?

There are many reasons why someone would want to choose stereolithography as a means of 3D printing. The most important: SLA is incredibly precise and high definition. Many people will want to use SLA because of the accuracy that can be achieved when SLA is the process applied to making 3D models. The layers of SLA can be 0.002” or thinner and often invisible to the naked eye. Additionally, sla surfaces sand very easily making it ideal for aesthetic models.

In addition to being accurate, SLA connects each layer to each other on a molecular level that results in an incredibly strong model. Compared to filament extrusion this gives you much better isotropic mechanical properties. The models are smooth, fully dense and watertight, everything you need for a solid 3D printer model. 

Getting Started With SLA

When you want to get started with stereolithography, RapidMade is the company to turn to. With many years of service in the 3D industry, Rapid Made provides a variety of different services for those who need 3D models printed. To find out if stereolithography is appropriate for what you need, you can get a free quote today.

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