How Stereolithography (SLA) 3D Printing works

Advancements in 3D printing continue to change the way businesses approach prototyping and production. As the technology becomes more accessible and affordable and hardware and materials advance to match market opportunities and demands, designers, engineers, and beyond are integrating 3D printing into workflows across development cycles.

Across industries, 3D printing is helping professionals cut outsourcing costs, iterate faster, optimize production processes, and even unlock entirely new business models.

Stereolithography 3D printing in particular has undergone significant changes. Traditionally, resin 3D printers have been monolithic and cost-prohibitive, requiring skilled technicians and costly service contracts. Today, small format desktop printers produce industrial-quality output, at substantially more affordable price points and with unmatched versatility.

What is Stereolithography 3D Printing?

Stereolithography belongs to a family of additive manufacturing technologies known as vat photopolymerization, commonly known as resin 3D printing. These machines are all built around the same principle, using a light source—a laser or projector—to cure liquid resin into hardened plastic. The main physical differentiation lies in the arrangement of the core components, such as the light source, the build platform, and the resin tank.

SLA 3D printers use light-reactive thermoset materials called “resin.” When SLA resins are exposed to certain wavelengths of light, short molecular chains join together, polymerizing monomers and oligomers into solidified rigid or flexible geometries.

A graphic representation of the basic mechanics of stereolithography (SLA) 3D printing.

SLA parts have the highest resolution and accuracy, the sharpest details, and the smoothest surface finishes of all 3D printing technologies, but the main benefit of the stereolithography lies in its versatility.

Material manufacturers have created innovative SLA resin formulations with a wide range of optical, mechanical, and thermal properties to match those of standard, engineering, and industrial thermoplastics.

The SLA 3D Printing Workflow

1. Design

Use any CAD software or 3D scan data to design your model, and export it in a 3D printable file format (STL or OBJ). Each SLA printer includes software to specify printing settings and slice the digital model into layers for printing. Once setup is complete, the print preparation software sends the instructions to the printer via a wireless or cable connection.

2. Print

After a quick confirmation of the correct setup, the printing process begins and the machine can run unattended until the print is complete. In printers with a cartridge system, the material is automatically refilled by the machine.

3. Post-Process

Once the printing is completed, parts require rinsing in isopropyl alcohol (IPA) to remove any uncured resin from their surface. After rinsed parts dry, some materials require post-curing, a process which helps parts to reach their highest possible strength and stability. Finally, remove supports from the parts and sand the remaining support marks for a clean finish. SLA parts can be easily machined, primed, painted, and assembled for specific applications or finishes.