What is the key difference between SLA and other 3D printing methods like FDM or SLS?

Core Printing Mechanism

The key difference lies in how the material is solidified. Stereolithography (SLA) uses a UV laser to cure liquid photopolymer resins into solid layers, resulting in exceptionally smooth surfaces and high resolution. In contrast, Fused Deposition Modeling (FDM) melts and extrudes thermoplastic filaments such as PLA or ABS, while Selective Laser Sintering (SLS) fuses powdered materials like nylon using a high-power laser.

Precision and Surface Finish

SLA delivers the highest level of detail and the smoothest finish among plastic 3D printing technologies. Its laser-curing mechanism produces thin layers and fine feature resolution ideal for visual prototypes, medical models, microfluidic devices, and highly detailed components. FDM cannot match SLA’s detail due to visible layer lines, and SLS, while strong and functional, produces a granular surface requiring post-processing.

Material Properties and Application Fit

SLA materials are resin-based and excellent for accuracy, but they may not match the mechanical toughness of FDM thermoplastics or SLS nylon powders. For functional parts with high durability, FDM and SLS typically outperform SLA. SLA is favored when precision, surface aesthetics, and intricate geometry are the primary requirements.