Question 1

What is SLS 3D printing?

Accepted Answer

SLS (selective laser sintering) fuses fine nylon powder layer by layer with a laser. The unfused powder supports the part, so it needs no support structures and can print complex, interlocking geometry with strong, near-isotropic properties.

Question 2

What materials can SLS print?

Accepted Answer

The most common is PA12 (nylon 12), plus PA11 for more ductility and impact resistance, glass-filled nylon (PA12-GF) for stiffness and heat resistance, and TPU powder for flexible parts. MJF runs a similar nylon set.

Question 3

What tolerance can SLS hold?

Accepted Answer

Typical SLS tolerance is about +/- 0.3% of the dimension, with a minimum of roughly +/- 0.3 mm. Well-controlled machines hold tighter. Call out critical features so the shop can confirm feasibility.

Question 4

SLS vs FDM: which is stronger?

Accepted Answer

SLS is generally stronger and more uniform because parts are near-isotropic, where FDM is weaker between layers (the Z direction). SLS also handles complex geometry with no supports, while FDM is cheaper and better for large parts.

Question 5

Does SLS need support structures?

Accepted Answer

No. The surrounding powder bed supports the part during the build, so there are no supports to remove and no support marks. That is what lets SLS print lattices, enclosed features, and interlocking assemblies.

Design rule	Typical spec	Why
Typical tolerance	+/- 0.3% (min +/- 0.3 mm)	As-sintered; tighter on well-controlled machines.
Min wall thickness	0.7 to 1.0 mm	Thinner walls warp or fail to fuse.
Min feature size	0.5 mm	Below the laser spot, fine detail blurs.
Support material	none needed	The powder bed supports the part, so there are no supports to remove.
Clearance for moving parts	0.4 to 0.5 mm	Tighter gaps fuse mating parts together.
Escape holes (hollow parts)	>= 4 mm, two holes	Let trapped powder drain out of enclosed volumes.

Process	Best for	Typical volume	Choose it over SLS 3D Printing when
FDM / FFF	Cheap prototypes, large parts	Prototype to low volume	You want the lowest cost or a large part and can accept layer lines and weaker Z strength.
MJF	Fine features, faster batches	Low-volume production	You want similar nylon parts with slightly finer detail and faster throughput.
Injection Molding	High-volume identical plastic parts	1,000+	You are past a few hundred parts and can amortize a mold for lower per-part cost.
CNC Machining	Tight tolerance, engineering materials	Prototype to production	You need tighter tolerances, a smoother finish, or a specific engineering-grade material.

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