FDM vs SLS: Which Technology Should You Choose?
A data-driven comparison of Fused Deposition Modeling and Selective Laser Sintering to help you select the right process for your application.
What Are FDM and SLS 3D Printing?
FDM and SLS represent two fundamentally different approaches to additive manufacturing. FDM builds parts by extruding thermoplastic filament through a heated nozzle, layer by layer, onto a build plate. SLS fuses powdered polymer (typically PA12 nylon) using a CO2 laser in a heated powder bed. The choice between them affects every aspect of your project: geometry complexity, surface finish, mechanical properties, cost structure, and lead time.
This guide compares both technologies using real specifications from our production equipment. FDM prints on a 500 × 500 × 500 mm build volume with ±0.15 mm tolerance, while SLS offers a 250 × 210 × 210 mm build volume with ±0.10 mm tolerance. Understanding where each technology excels will help you make the right decision for your specific application.
How Do FDM and SLS Compare?
| FDM | SLS | |
|---|---|---|
| Layer Height | 0.1–0.3 mm | 0.1 mm |
| Tolerance | ±0.15 mm | ±0.10 mm |
| Build Volume | 500 × 500 × 500 mm | 250 × 210 × 210 mm |
| Materials | PLA, PETG, ASA, Nylon, PC-CF, PA-GF, PP | PA12 |
| Support Structures | Required | None (self-supporting powder) |
| Surface Finish | Layer lines visible | Slightly grainy |
| Strength | Anisotropic | Near-isotropic |
| Cost per Part | € (low) | €€ (medium) |
| Best For | Prototypes, large parts, functional tests | Complex geometries, small batches, end-use parts |
When Should You Choose FDM Over SLS?
FDM is the better choice when you need fast turnaround on functional prototypes, have budget constraints, or require a specific engineering thermoplastic like ASA for UV stability, PP for chemical resistance, or PC-CF for extreme stiffness. FDM also wins for large single-piece parts (up to 500 × 500 × 500 mm without splitting) and when same-day production is critical. However, FDM parts require support structures for overhangs, which means complex internal geometries or interlocking assemblies may require design compromises. Layer lines are visible at 0.10-0.30 mm, so cosmetic applications may need post-processing.
How Do You Decide Between FDM and SLS?
Choose FDM if your priority is material variety, cost efficiency, or fast turnaround on parts where layer visibility is acceptable. Choose SLS if you need complex geometries without supports, isotropic strength, or batch production of identical parts. For visual models requiring the finest surface finish, consider mSLA resin instead. Not sure which technology fits? Upload your model and our team will recommend the optimal process based on your geometry, material needs, and budget.
Frequently Asked Questions
Is FDM or SLS stronger?
It depends on the material. FDM with Nylon (85 MPa) or PA-GF (95 MPa) produces parts with higher tensile strength than SLS PA12 (48 MPa). However, SLS parts are isotropic (equally strong in all directions) while FDM parts are weaker between layers.
Which is cheaper for a single prototype?
FDM is almost always cheaper for single parts due to lower material costs and faster setup. SLS becomes competitive when you need 10+ identical parts, because the powder bed can be filled with multiple parts in a single job.
Can SLS replace injection molding?
For small to medium batches (up to ~500 parts), SLS PA12 can serve as a bridge to injection molding or even replace it for low-volume production. The material properties are similar to injection-molded PA12.
Do FDM parts need support structures?
Yes, FDM requires supports for overhangs greater than ~45 degrees. This means internal channels, snap fits, and interlocking features may need design adjustments. SLS requires no supports since the powder bed itself supports the part.
Which technology has better dimensional accuracy?
SLS achieves ±0.10 mm tolerance compared to FDM's ±0.15 mm. For applications requiring tight tolerances, SLS is the better choice. For most functional prototypes, both are adequate.
Need Help Choosing?
Upload your model for an instant quote, or contact our team for a personalized technology recommendation.