Stereolithography is the first RP process and is still the most utilized of all types of Rapid Prototyping, like medical rapid prototyping, 90% of all Rapid Prototyping is "Stereolithography"...






Stereolithography, also known as 3-D layering or 3-D printing, allows you to create solid, plastic, three-dimensional (3-D) objects from CAD drawings in a matter of hours. Whether you are a mechanical engineer wanting to verify the fit of a part or an inventor looking to create a plastic prototype of an invention, stereolithography gives you a fast, easy way to turn CAD drawings into real objects.

3-D printing is a very good example of the age we live in. In the past, it could conceivably take months to prototype a part -- today you can do it hours. If you can dream up a product, you can hold a working model in your hands two days later!

The Stereolithography Process
The basic printing process goes like this:
You create a 3-D model of your object in a CAD program
A piece of software chops your CAD model up into thin layers -- typically five to 10 layers/millimeter
The 3-D printer's laser "paints" one of the layers, exposing the liquid plastic in the tank and hardening it
The platform drops down into the tank a fraction of a millimeter and the laser paints the next layer
This process repeats, layer by layer, until your model is complete

This is not a particularly quick process. Depending on the size and number of objects being created, the laser might take a minute or two for each layer. A typical run might take six to 12 hours. Runs over several days are possible for large objects (maximum size for the machine shown above is an object 10 inches (25 cm) in three dimensions).






A typical CAD drawing ready to be rendered on the 3-D printer. This particular piece is a plastic money clip that PT CAM gives away to visitors. Note the supports (in red) that separate the money clip from the tray and support it is it is being built. About 50 of these money clips can be created in a single run.


You start by creating a 3-D design for your object in a CAD program. This design is tweaked before building with supports that raise it up off the tray slightly and with any internal bracing that is required during building. The SLA then renders the object automatically (and unattended). When the process is complete, the SLA raises the platform and you end up with your 3-D object. If the object is small, you can produce several of them at the same time if you like. They all sit next to each other on the tray.






The platform in the tank of photopolymer at the beginning of a print run.


The following photo shows a tray after building is complete, with several identical objects that were produced simultaneously:







The platform at the end of a print run, shown here with several identical objects.


Once the run is complete, you rinse the objects with a solvent and then "bake" them in an ultraviolet oven that thoroughly cures the plastic.






The ultraviolet "oven" used to cure completed objects.