Nylon 3D Printing: FDM vs. SLS for Functional Prototypes

Nylon 3D Printing: FDM vs. SLS for Functional Prototypes and Small-Batch Production

The choice between FDM (fused deposition modeling) and SLS (selective laser sintering) for nylon parts is one of the most consequential process decisions in additive manufacturing. Both use nylon — but the mechanical properties, surface quality, design freedom, and cost structures are fundamentally different.

This guide cuts through the marketing noise to give engineering buyers a clear decision framework. We cover the technical realities of each process, a direct property comparison, and real-world guidance for common applications in automotive, industrial equipment, and consumer products.

SLS 3D printing process with nylon powder — Nylon Plastic

Process Fundamentals: How FDM and SLS Actually Work

Understanding the mechanical difference between the two processes explains most of the property and quality trade-offs that follow.

FDM (Fused Deposition Modeling) extrudes molten nylon filament layer by layer through a heated nozzle (typically 230-280°C for nylon). Parts are built on a heated bed, and support structures are printed in the same or a breakaway filament. The bond between layers is primarily thermal diffusion — not molecular fusion — making layer adhesion the primary weakness.

SLS (frittage sélectif par laser) fuses nylon powder (typically PA12) using a high-power laser that sinters powder particles together in a heated build chamber (typically 170-190°C). No support structures are needed because unsintered powder supports overhanging geometry. Parts are fully dense in all directions — more isotropic than FDM.

FDM 3D printing extrusion process — Nylon Plastic

Mechanical Property Comparison

The table below presents tensile, impact, and thermal properties for nylon FDM and SLS parts tested per ISO standards. Values represent typical properties of well-optimized parts.

Propriété	PA12 SLS (typical)	PA6 FDM (typical)	PA6 FDM (optimized)	Notes
Résistance à la traction (MPa)	46-50	40-50	50-58	SLS PA12 limited by porosity
Tensile Modulus (GPa)	1.7-1.9	1.5-1.8	1.7-2.0	Similar range
Allongement à la rupture	10-15%	20-50%	15-30%	FDM more ductile
Notched Izod Impact (kJ/m²)	4.5-6.0	3-5	5-8	SLS better for PA12
HDT at 1.82 MPa (°C)	175-182	65-75	65-75	SLS PA12 much higher
Moisture Absorption (24h)	0.5-1.0%	5-8%	5-8%	PA12 far superior
Isotropy	High (90%+)	Low (60-70%)	Faible	FDM highly anisotropic
Surface Roughness (Ra, µm)	6-12	8-15	5-10	SLS smoother after bead blast

Design Envelope: What Each Process Can and Cannot Do

Beyond mechanical properties, the geometric capabilities of each process determine which applications each can serve.

Design Factor	FDM Nylon	SLS Nylon (PA12)	Winner
Minimum wall thickness	0.8 mm	0.5 mm	SLS
Minimum feature size	0.5 mm	0.3 mm	SLS
Overhang requirements	Requires supports	Self-supporting	SLS
Internal channels	Requires supports	Natural hollow printing	SLS
Large parts (>300mm)	Bon	Limited by build volume	FDM
Dimensional tolerance	±0.3 mm	±0.2 mm	SLS
Smooth surface finish	Poor (layer lines)	Moderate (rough powder)	SLS
Post-processing ease	Easy (sand, paint)	Moderate (vapor smooth)	FDM

Material Cost and Production Economics

For engineering buyers evaluating 3D printing against CNC or injection molding, understanding total part cost — not just material price — is essential.

Cost Factor	FDM (Nylon)	SLS (PA12)	Notes
Material cost ($/kg)	$45-80	$60-110	SLS powder more expensive
Machine cost (depreciation)	Low-Medium	Haut	SLS machines 3-5x more expensive
Support material waste	10-30%	0% (unused powder reusable)	SLS wins for complex parts
Post-processing labor	Moyen	Low-Medium	Depends on surface requirement
Batch efficiency	Low (serial printing)	High (stackable parts)	SLS wins for batches
Best economics	Prototypes, large parts	Small complex parts, batches	Process selection by geometry

Application-Specific Recommendations

The right process depends on your application’s requirements — there is no universally superior technology.

Application	Recommended Process	Matériau	Why
Functional gears (dry environment)	SLS or FDM PA6-CF	SLS PA12 or PA6-GF FDM	Strength and wear resistance
Functional gears (wet/oily)	SLS PA12	PA12 SLS	Chemical resistance, low moisture
Snap-fits and living hinges	FDM PA6	PA6 FDM filament	Ductility, flexibility
Chemical-resistant enclosures	SLS PA12	PA12 SLS	Broad chemical resistance
Large housings and covers	FDM PA6-GF30	PA6-GF30 FDM	Large format, structural
High-heat components (>150°C)	SLS PA12	PA12 SLS	HDT 175°C vs 70°C for FDM
Low-volume bridge production	SLS PA12	PA12 SLS	No tooling, batch economics
Early-stage prototypes	FDM PA6	PA6 or PA66 FDM	Lowest cost, fastest turnaround

FAQ

When is Nylon 3D Printing: FDM vs. SLS for Functional Prototypes a good option?

Nylon 3D Printing: FDM vs. SLS for Functional Prototypes is a good option when fast iteration, complex geometry, low tooling cost, or low-volume production is more important than molded-part unit cost.

What should be checked before choosing Nylon 3D Printing: FDM vs. SLS for Functional Prototypes?

Vérifier la taille de la pièce, les propriétés du matériau, l'état de surface, la tolérance dimensionnelle, l'exposition à la chaleur, la direction de la charge et la nécessité d'un post-traitement.

How does Nylon 3D Printing: FDM vs. SLS for Functional Prototypes compare with CNC machining?

L'impression 3D permet de créer rapidement des formes complexes, tandis que l'usinage CNC est souvent plus performant pour les surfaces précises, les tolérances plus étroites et les matériaux de qualité.

What affects the cost of Nylon 3D Printing: FDM vs. SLS for Functional Prototypes?

Le coût dépend du matériau, du volume de construction, du temps d'impression, de la hauteur des couches, de l'enlèvement du support, de la finition, de l'inspection et du nombre de pièces dans la construction.

Nylon 3D Printing: FDM vs. SLS for Functional Prototypes