Process selection
FDM vs SLA vs SLS vs PolyJet: which 3D printing process is best?
FDM suits large parts and the lowest cost, building up to 1000 mm. SLA gives the finest detail and the tightest standard tolerance (minimum ±0.1 mm). SLS suits strong, support-free PA12 nylon parts and batches. PolyJet combines rigid and flexible materials in one part. Narrow the choice by size first, then detail, then material.
Reviewed by HenleyPrint3D engineers3 min readUpdated
Key takeaways
- Largest parts: FDM, up to 1000 mm.
- Finest detail and tightest standard tolerance: SLA.
- Strong, support-free nylon parts and batches: SLS.
- Rigid and flexible in one part: PolyJet.
Suits
Engineers comparing the four polymer processes before picking one.
Worth knowing
Size narrows it fastest: FDM to 1000 mm, SLA to 350 mm, SLS to 165 × 165 × 300 mm.
Process comparison
| FDM | SLA | SLS | PolyJet | |
|---|---|---|---|---|
| Max build | 1000 × 1000 × 1000 mm | 350 × 250 × 250 mm | 165 × 165 × 300 mm | Quoted per part |
| Tolerance | ±0.5% (min ±0.3 mm) | ±0.5% (min ±0.1 mm) | ±0.3% (min ±0.3 mm) | Quoted per part |
| Layer height | From 50 microns | From 10 microns | From 50 microns | 16 to 30 microns |
| Min wall | 1.0 to 1.2 mm | 0.5 to 1.0 mm | 0.7 to 1.0 mm | Quoted per part |
| Lead time from | 1 calendar day | 1 calendar day | 2 calendar days | Quoted per part |
| Supports | Yes | Yes | None (powder) | Yes |
Which process for which requirement?
| If you need | Choose |
|---|---|
| A part longer than 350 mm | FDM |
| Smooth surface and small features | SLA |
| Snap fits, hinges, housings, batches of small parts | SLS |
| Soft and rigid regions together | PolyJet |
| Heat or flame rating | FDM industrial grades (ULTEM on request) |
| Lowest cost | FDM |
How to read the comparison
Look at the build volume first, then the tolerance minimum, then the minimum wall. Together they remove most options. Then match the material: FDM covers PLA to ULTEM on request, SLA covers resins from standard to flexible and transparent, SLS prints PA12 nylon, and PolyJet mixes rigid and flexible photopolymers. If two processes remain, the cheaper and faster one is usually FDM.
For a step-by-step method, see how to choose a 3D printing process. Each process has its own service page: FDM 3D printing, SLA 3D printing, SLS 3D printing and PolyJet 3D printing.
Frequently asked questions
Which 3D printing process is strongest?
SLS in PA12 nylon is generally the strongest and most consistent for functional polymer parts, with near-isotropic behaviour. FDM in ABS, PETG or nylon can be similarly strong along the layers but is weaker across them.
Which 3D printing process is the most accurate?
SLA and PolyJet achieve the finest detail and smoothest surfaces. On our service SLA reaches a minimum tolerance of about ±0.1 mm, compared with about ±0.3 mm for FDM and SLS.
Which process is cheapest?
FDM is usually the cheapest per part, followed by SLS for batches, then SLA and PolyJet. The finished cost also depends on how much finishing the part needs.
Can I switch process between prototype and production?
Often yes, but properties and tolerances differ. Validate the design in the final process and material where possible, and use FDM or SLA early for cheap iteration.
How do I choose between SLS and FDM nylon?
SLS offers better isotropy, detail and no supports, and suits batches. FDM nylon suits larger parts and lower cost. The geometry and quantity usually decide it.
Get started
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