Stereolithography (SLA) is an industrial 3D printing process used to create concept models, cosmetic prototypes, and complex parts with intricate geometries in as fast as 1 day. A wide selection of materials, extremely high feature resolutions, and quality surface finishes are possible with SLA. SLA is a go-to choice for 3D printed models that require accurate features and a smooth surface finish.
How Does SLA 3D Printing Work?
A photosensitive suspension (photopolymer resin) is exposed by light (of certain wavelength) so it cures. The exposure pattern for each 3D slice is defined by a 2D photo mask (ultraviolet (UV) laser, UV light projector/DLP or LCD). After a layer is photocured, the Z axis moves up for the next layer of the 3D object. An FEP film clamped against the glass is used as the release layer.
There exist three common photo mask and light source combinations:
-ultraviolet (UV) laser
-Digital light processing (DLP) projector and UV lamp
-LCD panel and UV lamp
The type of photopolymer resin used (visible-light-curing or ultraviolet (UV)-curing) has to match the type of photo mask and light source combination.
Example:
-resin: UV-curing resin with absorption range 250 to 450 nm
-light source: UV lamp/LED 405 nm
-photo mask: LCD panel allowing to pass the UV lamp frequency 
Why Use SLA?
SLA 3D prints are often used for final fit checks before moving to injection molding services. Stereolithography is an additive manufacturing process that can 3D print parts with small features, tight tolerance requirements, and smooth surface finishes.
