What is the difference between SLA, SLS, and FDM 3D printing technologies?

Quick Answer

SLA cures liquid resin with UV light for the finest detail and smoothest surfaces (25-micron layers). SLS fuses nylon powder with laser for strong, functional parts without supports (100-micron layers). FDM melts plastic filament for economical, durable parts (100-300-micron layers). Choose SLA for detail and finish, SLS for function and complexity, and FDM for budget and strength.

SLA - Detail Champion

SLA produces the highest resolution and smoothest surface finish of any 3D printing technology. Layer height: 25-100 microns. Surface finish: 0.5-1.5 Ra. Best for: presentation models, jewelry patterns, dental models, and any application where surface quality matters. Limitations: parts are more brittle than SLS or FDM, resin materials degrade under prolonged UV exposure, support structures required. Cost per part: medium.

SLS - Function Champion

SLS produces durable, functional parts from nylon powder. No support structures needed because unsintered powder supports the part. This allows complex geometries, moving assemblies, and interlocking parts. Layer height: 100-120 microns. Nylon 12 parts have excellent fatigue resistance, chemical resistance, and impact strength. Limitations: surface finish is matte and granular (3-6 Ra), higher cost than FDM. Cost per part: medium-high.

FDM - Economy Champion

FDM is the most economical 3D printing technology. Layer height: 100-300 microns. Materials include PLA (easiest), ABS (stronger, heat resistant), PETG (tough, food-safe), PC (engineering grade), and Nylon. Parts are strong and durable but have visible layer lines. Limitations: surface finish is rough (10-30 Ra), overhangs require support structures, layer adhesion can be weak in Z-direction. Cost per part: low.

Selection Guide

$50 budget, need prototype in 1 day, strength not critical: FDM. Need presentation-quality surface, fine details, smooth finish: SLA. Need functional testing, complex geometries, nylon properties: SLS. Need metal properties: SLM. Budget unlimited, need production-quality surface: CNC machining. For most product development projects, SOMI recommends starting with SLA for look-and-feel prototypes, then switching to SLS or CNC for functional testing.

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