stereolithography

Stereolithography is an additive manufacturing process that creates three-dimensional parts by curing a liquid photosensitive resin with light, typically a ultraviolet laser, layer by layer to form solid geometry. It was developed in the 1980s and commercialized by 3D Systems in 1987; the term is closely associated with the original laser-based system invented by Chuck Hull.

In operation, a vat of liquid photopolymer sits beneath a build platform. The platform starts near the resin surface, and a light source selectively solidifies resin at the current layer’s cross-section. After a layer is cured, the platform lowers by a defined thickness and a recoater applies fresh resin. The cycle repeats, building the part from bottom to top. Laser-based SLA traces the pattern point by point or along vectors, while digital light processing (DLP) SLA cures an entire layer at once with a projected image.

Materials used are photosensitive resins formulated for properties such as stiffness, heat resistance, transparency, and biocompatibility. After printing, parts are typically rinsed to remove uncured resin and then post-cured under UV or visible light to achieve full strength and stability.

Advantages include high dimensional accuracy and smooth surface finishes, making SLA well suited for detailed prototypes, tooling patterns, dental and medical models, and complex geometries. Limitations include brittle resin materials, a relatively narrow range of engineering plastics compared to other methods, resin handling hazards, post-processing requirements, and potential anisotropy from layering. Build size is also constrained by the printer design and resin vat.

Applications span rapid prototyping, dental and orthodontic models, jewelry casting patterns, aerospace and automotive prototyping, and small-batch production of precise components.