How does FDM 3D printing differ from SLA and SLS?

How Does FDM 3D Printing Differ from SLA and SLS?

1. Printing Technology and Process

FDM (Fused Deposition Modeling): FDM extrudes melted thermoplastic filament (e.g., PLA, ABS, PETG) through a heated nozzle to build parts layer by layer. It is widely used for low-cost prototyping and mechanical components.

SLA (Stereolithography): SLA uses a UV laser to cure liquid photopolymer resin in a vat. It produces high-resolution parts with smooth surfaces, ideal for visual models and medical applications.

SLS (Selective Laser Sintering): SLS uses a laser to fuse powdered materials, usually Nylon (PA), layer by layer in a heated chamber. It produces functional, durable parts with no support structures required.

2. Material Compatibility

FDM: Compatible with thermoplastic filaments like PLA, ABS, PETG, TPU, and PEEK.

SLA: Uses photopolymer resins such as standard, tough, flexible, high-temperature, dental, and biocompatible grades.

SLS: Commonly uses thermoplastic powders like Nylon (PA), glass-filled PA, and elastomers. No supports are needed, as the surrounding powder provides part stability.

3. Print Resolution and Surface Finish

FDM: Moderate resolution (layer height ~100–300 μm). Parts may show visible layer lines and require post-processing for smoothness.

SLA: High resolution (25–100 μm) with smooth surfaces, ideal for detailed and cosmetic parts.

SLS: Moderate to high resolution (~100 μm). Surface has a powdery texture but good mechanical properties.

4. Strength and Functional Use

FDM: Good for simple mechanical prototypes and large parts. Limited isotropic strength and lower detail fidelity.

SLA: Excellent for visual prototypes and medical models, but resins are generally brittle and less suitable for load-bearing parts.

SLS: Best for functional, load-bearing, end-use parts. Excellent mechanical strength and durability.

5. Support Structures and Post-Processing

FDM: Requires support structures that must be removed manually or dissolved.

SLA: Requires printed supports that are clipped and surfaces sanded or cured.

SLS: No supports required. Requires depowdering but minimal cleanup.

Comparison Table

Recommended 3D Printing Services

Material Extrusion (FDM): For budget-friendly mechanical parts

Vat Photopolymerization (SLA/DLP): For smooth-surface, detailed models

Powder Bed Fusion (SLS): For strong, functional parts with no support structures