FDM vs SLA vs SLS vs DMLS:
- FDM uses melted plastic filament; SLA uses liquid resin cured by laser.
- SLS fuses plastic powder; DMLS fuses metal powder for strong parts.
- FDM is cheapest, SLA is high-detail, SLS is durable, and DMLS is for metal/industrial use.
In this article:
FDM vs SLA vs SLS vs DMLS
Here’s a detailed comparison of FDM, SLA, SLS, and DMLS, the four most common 3D printing technologies. Each uses a different working principle, material type, and application area.
Definition:
FDM (Fused Deposition Modeling)
- Melts and extrudes thermoplastic filament layer by layer.
SLA (Stereolithography)
- Uses a UV laser to cure liquid photopolymer resin.
SLS (Selective Laser Sintering)
- Uses a laser to sinter polymer powder (usually nylon).
DMLS (Direct Metal Laser Sintering)
- Uses a laser to fuse metal powder into solid parts.
1. Working Principle
FDM
- Heated nozzle deposits molten plastic.
SLA
- Laser solidifies liquid resin in a vat.
SLS
- Laser sinters powdered plastic.
DMLS
- Laser fuses powdered metal.
2. Materials Used
FDM
- PLA, ABS, PETG, TPU
SLA
- Photopolymer resins (standard, tough, flexible)
SLS
- Nylon (PA12), glass-filled nylon
DMLS
- Metals like:
- Titanium
- Stainless steel
- Cobalt-chromium
- Aluminum
3. Accuracy & Surface Finish
FDM
- Lowest accuracy
- Visible layer lines
SLA
- Very high accuracy
- Smoothest surface finish
SLS
- Moderate accuracy
- Slightly rough, grainy
DMLS
- High accuracy
- Rough metallic finish (needs post-processing)
4. Strength & Durability
FDM
- Moderate strength
- Weak layer bonding
SLA
- Brittle (can crack easily)
SLS
- Strong and functional
- Good impact resistance
DMLS
- Very high strength (near-solid metal)
5. Support Structures
FDM
- Required
SLA
- Required
SLS
- Not required (powder supports part)
DMLS
- Required (for heat dissipation & stability)
6. Production Speed
FDM
- Slow to moderate
SLA
- Moderate
SLS
- Faster (can print multiple parts at once)
DMLS
- Slow (metal process is time-consuming)
7. Cost
FDM
- Cheapest
SLA
- Moderate
SLS
- Expensive
DMLS
- Very expensive
8. Applications
FDM
- Prototyping
- Educational use
- Hobby projects
SLA
- Dental models
- Jewelry casting patterns
- High-detail prototypes
SLS
- Functional plastic parts
- Automotive components
DMLS
- Aerospace parts
- Medical implants
- Dental crowns/bridges
9. Post-Processing
FDM
- Minimal (support removal, sanding)
SLA
- Washing + UV curing required
SLS
- Powder cleaning
DMLS
- Extensive:
- Support removal
- Heat treatment
- Machining/polishing
Summary Table
| Feature | FDM | SLA | SLS | DMLS |
|---|---|---|---|---|
| Material | Plastic filament | Liquid resin | Polymer powder | Metal powder |
| Accuracy | Low | Very high | Medium | High |
| Surface Finish | Rough | Smooth | Grainy | Rough metal |
| Strength | Moderate | Brittle | Strong | Very strong |
| Supports | Yes | Yes | No | Yes |
| Cost | Low | Medium | High | Very high |
| Applications | Basic prototypes | High-detail models | Functional parts | Industrial/medical |
Applications
Use FDM when:
- Low cost is important
- Simple prototypes are needed
Use SLA when:
- High detail and smooth finish are required
- Dental/jewelry applications
Use SLS when:
- Strong plastic parts are needed
- No supports desired
Use DMLS when:
- Metal parts are required
- High strength and industrial use
Conclusion:
- FDM = Cheap & simple
- SLA = Smooth & detailed
- SLS = Strong plastic
- DMLS = Strong metal
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