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NODEFAB · TECHNOLOGY SELECTION

FDM vs SLA vs SLS vs MJF: Which 3D Printer for Which Application?

14 min read

This article is available in English only.

The Hidden Cost of Choosing the Wrong Technology

A startup orders 50 functional prototypes using FDM. The parts arrive with visible layer lines, inconsistent wall thickness on thin features, and support scarring on critical sealing surfaces. 40 of the 50 parts fail leak testing. The correct choice was MJF — and using it from the start would have cost less than one failed test batch.

Technology selection errors are more expensive than the per-part price difference. This guide gives you the engineering criteria to choose correctly the first time.

Technology Overview

┌─────────────────────────────────────────────────────────────────┐
│   Technology     Process                Material State      │
├─────────────────────────────────────────────────────────────────┤
│   FDM (FFF)      Extrusion              Thermoplastic filament│
│   SLA (MSLA)     Photopolymerization    Liquid resin          │
│   SLS            Powder bed fusion      Polymer powder        │
│   MJF            Multi Jet Fusion       PA powder + binder    │
└─────────────────────────────────────────────────────────────────┘

FDM (Fused Deposition Modeling)

How it works: A thermoplastic filament is melted and extruded through a nozzle, building the part layer by layer. The most accessible 3D printing technology.

Dimensional accuracy: ±0.2-0.5mm for typical consumer/prosumer machines. Industrial FDM (Stratasys Fortus) achieves ±0.1mm.

Surface finish: Layer lines are always visible on sloped surfaces. Z-direction surface is roughest. Minimum feature size: ~0.5mm walls (reliable).

Supports: Required for overhangs >45°. Support removal leaves witness marks, which can be critical for mating surfaces.

Materials available: PLA, PETG, ABS, ASA, TPU, Nylon, PEI, PEEK (with high-temp printers). Widest material selection of any additive process.

Key advantages:

Key limitations:

Best for: Large structural prototypes, jigs and fixtures, low-volume end-use parts in engineering plastics, cost-sensitive applications.

Not suitable for: Watertight thin walls, very fine features (<0.3mm), isotropic strength requirements, production-quality surface finish without extensive post-processing.

SLA (Stereolithography)

How it works: A UV laser (or in MSLA/LCD printers, an LCD masked UV panel) cures liquid photopolymer resin layer by layer. Parts are built hanging from a build plate (bottom-up) or sitting on a platform (top-down, traditional SLA).

Dimensional accuracy: ±0.05-0.1mm. The best accuracy of any common 3D printing process for small-medium parts.

Surface finish: Excellent. Layer lines are present (typically 25-100µm) but much finer than FDM. Post-wash-and-cure process required. Final surface is often comparable to injection molding for visual parts.

Minimum feature size: Down to 0.1mm for professional resins. Tiny details, text, and fine structures come out crisply.

Supports: Required for overhangs. SLA supports are thin and easily removed, leaving smaller marks than FDM. Breakaway or dissolvable supports available.

Materials available: Standard resins, ABS-like, flexible, dental, castable (for jewelry/casting), biocompatible. Properties generally inferior to engineering thermoplastics for load-bearing use.

Key advantages:

Key limitations:

Best for: Jewelry prototypes, dental models, visual prototypes requiring high surface quality, transparent prototypes, miniature models.

Not suitable for: Functional parts requiring impact resistance, high-temperature applications, outdoor use without coating.

SLS (Selective Laser Sintering)

How it works: A CO₂ laser sinters thermoplastic powder (typically PA12 Nylon) layer by layer. Unsintered powder supports the part, eliminating the need for support structures.

Dimensional accuracy: ±0.2-0.3mm for PA12. Less precise than SLA but better than typical FDM for complex geometry.

Surface finish: Grainy/textured (powder particle size visible). Parts look and feel like sandpaper (Ra ~10-20µm) without post-processing. Dyeable, paintable, vibratory-finishable.

Supports: None required. This is the transformative advantage of SLS. Any geometry is printable without support considerations — undercuts, internal channels, interlocking parts, hinges within the print.

Materials: Primarily PA12 (Nylon 12). Also PA11, TPU powders, glass-filled PA, alumide. More limited than FDM but all engineering-grade.

Key advantages:

Key limitations:

Best for: Functional parts requiring complex geometry (living hinges, snap fits, assemblies), production-ready end-use parts, engineering testing with isotropic properties.

Not suitable for: Cost-sensitive single prototypes (minimum order economics apply), applications requiring smooth out-of-machine surface finish, transparent parts.

MJF (Multi Jet Fusion, HP)

How it works: HP's proprietary powder bed process jets a fusing agent onto PA12 powder and uses an infrared heating pass to sinter it. A detailing agent along boundaries sharpens edges. Much faster than SLS for production volumes.

Dimensional accuracy: ±0.2-0.3mm, comparable to SLS.

Surface finish: Smoother than SLS out of the machine (finer gray surface). Consistent gray-black color due to the fusing agents. Dye-able to other colors.

Supports: None required (same advantage as SLS).

Materials: Primarily HP PA12 and PA11. HP also offers TPU and glass-filled grades.

Key advantages:

Key limitations:

Best for: Medium-to-high volume functional part production, applications requiring consistent part-to-part quality, complex geometry without supports, end-use production parts.

Decision Matrix

┌────────────────────────┬─────┬─────┬─────┬─────┐
│ Requirement              │ FDM │ SLA │ SLS │ MJF │
├────────────────────────┼─────┼─────┼─────┼─────┤
│ Lowest cost/part         │ ✓✓  │ ✓   │     │     │
│ Highest surface finish   │     │ ✓✓  │ ✓   │ ✓   │
│ No supports needed       │     │     │ ✓✓  │ ✓✓  │
│ Isotropic properties     │     │     │ ✓✓  │ ✓✓  │
│ Finest features (<0.2mm) │     │ ✓✓  │     │     │
│ Largest build volume     │ ✓✓  │     │ ✓   │ ✓   │
│ Material variety         │ ✓✓  │ ✓   │ ✓   │     │
│ Production consistency   │ ✓   │ ✓   │ ✓   │ ✓✓  │
│ Transparent parts        │     │ ✓✓  │     │     │
│ Flexible/rubber parts    │ ✓   │     │ ✓   │ ✓   │
└────────────────────────┴─────┴─────┴─────┴─────┘

The Cost Curve: Quantity vs Technology

Cost/part
(€)

 50 |  FDM
 30 |  ··· SLA
 20 |  ——— SLS/MJF
    |
 10 |FDM────────────────────────
  8 |   SLA─────────────────────
  5 |         SLS/MJF────────────
  3 |               SLS/MJF (at vol.)
    ────────────────────────── Quantity
    1    5    10   50  100  500

 FDM is cost-competitive for 1-10 parts.
 SLS/MJF becomes cost-competitive at 20-50+ parts.
 The crossover point depends heavily on part geometry.

How Nodefab Handles Multi-Technology Quoting

Today Nodefab's instant quote covers FDM printing and CNC machining. Upload your part and you get a breakdown instead of a single number: material and labor for FDM — with support material and support removal priced when the part needs supports — and material, machining time, setup and labor for CNC.

Note: SLA, SLS and MJF quoting comes to Nodefab with the 2027 releases.

Until then, the criteria in this guide tell you when FDM is the right call — and when it isn't.

Conclusion

Technology selection is a multi-dimensional decision: accuracy, surface finish, material properties, support structures, quantity, and budget all interact. The "best" technology is always application-specific.

The practical framework: start with your performance requirements (feature size, material properties, surface finish), eliminate incompatible technologies, then use cost as the final differentiator between compatible options.

Ready to compare? Upload your part to Nodefab for an instant FDM or CNC quote today; SLA, SLS and MJF follow with the 2027 releases.