SLA and SLS are the two most common technologies in prototyping and short-run production. Both are polymer-based, but in nearly every other dimension they are opposites. We compare them across seven criteria.
Working principle
SLA uses a UV laser to cure liquid resin layer by layer. SLS uses a CO₂ laser to sinter nylon powder. This difference drives every other property.
Accuracy and finish
SLA wins easily – ±50µm and a near-mirror finish. SLS gives ±200µm and a grainy finish due to the bare-powder surface.
Mechanical strength
Here SLS wins. PA12 SLS parts are durable, flexible and suitable for real functional testing. SLA parts, even from tough resins, stay relatively brittle.
Supports and geometry
SLA requires supports for every overhang – leaving marks that need finishing. SLS needs no supports at all – the powder itself supports the part. This enables otherwise impossible geometries.
Cost
For a single unit, SLA is cheaper. For batches of 20+ units, SLS wins thanks to a large build volume that fills efficiently.
When to pick which
- Visual prototype or casting master → SLA
- Functional test or load-bearing mechanism → SLS
- Short series of end-use parts → SLS or MJF
- High-resolution marketing model → SLA