This method uses UV light to cure or harden resins layer by layer. The laser traces patterns onto liquid resin and hardens it. The object is raised as another layer is cured on top of the last. SLA is most often used by professional and high-level consumers for applications that require a high level of detail. Examples include jewelry, dentistry and more intricate
SLA is famous for being the first 3D printing technology, first patented in 1986.
If parts of very high accuracy or smooth surface finish are needed, SLA is the most cost-effective 3D printing technology available. Best results are achieved when the designer takes advantage of the benefits and limitations of the manufacturing process.
In SLA systems, most print parameters are fixed by the manufacturer and cannot be changed. The only inputs are the layer height and part orientation (the latter determines support location).
The typical layer height in SLA ranges between 25 and 100 microns. Lower layer heights capture curved geometries more accurately but increase the build time (and cost) and the probability of a failed print. A layer height of 100 microns is suitable for most common applications.
Support structure is always required in SLA. Support structures are printed in the same material as the part and must be manually removed after printing. The orientation of the part determines the location and amount of support. It is recommended that the part is oriented so that so visually critical surfaces do not come in contact with the support structures.
Post Processing - Selective Laser Sintering (SLS)
SLS parts produces parts with a powdery, grainy surface finish that can be easily stained. Their appearance can be improved to a very high standard using various post processing methods, such as media polishing, dyeing, spray painting and lacquering. Their functionality can also be enhanced by applying a watertight coating or a metal plating.
Advantages of SLA
Parts with high dimensional accuracy and intricate details.
Parts produced by SLA printing have a very smooth surface finish, making them ideal for visual prototypes.
Speciality SLA materials are available, such as clear, flexible and castable resins.
Disadvantages of SLA
Parts are generally brittle and not suitable for functional prototypes.
Mechanical properties and visual appearance degrade when the parts are exposed to sunlight.
Support structures are always required
Post-processing is necessary to remove the visual marks left on the SLA part.