SLA machines work hand-in-hand with a UV laser that activates the liquid photopolymer through polymerization in a vat. This is how SLA machines build a part:
First, a build platform is lowered into a vat containing liquid photopolymer. Next, a UV laser is used to cure the liquid. The UV laser scans the all the solidifying surface of the part that is being built.
And lastly, a part is completed by susbsequently lowering the build platform into the vat filled with liquid photopolymer. This is a not an easy process as the part is built layer by layer.
Minimum Lead Time
When to use SLA?
Aesthetically speaking, SLA can produce prototypes with very fine details, superb surface finishes, high quality acccuracy, great form/fit and sometimes functional testing. The materials in SLA have been especially and specifically developed by producers to mimic engineering materials' mechanic properties (in the short term), e.g. high heat resistance. It is also good for small-batch production.
When your products require smooth and great surface finishes, your casting patterns must be of very good accuracy; this can be achieved if your patterns are produced with SLA.
Pros of SLA
Stereolithography can build large parts with very good accuracy and surface finish. A wide range of material allow to build parts with specific characteristics.
Cons of SLA
One disadvantage of SLA is its limitation-- it can only work with photopolymer materials. The build process is also slow, not to mention that the materials are high-priced. Since SLA only works with photopolymer, part's mechanical properties are not as durable over time compared to other materials.
Despite being one of the oldest and pioneer 3D printing methods, stereolithography is still very popular up to this day. Rapid prototyping was made possible through SLA because it was the very first process especially developed for it.