3D print SLS: what is Selective Laser Sintering and how it works
SLS 3D printing — short for Selective Laser Sintering — is an advanced additive manufacturing method that uses a high-powered laser to fuse powdered materials into solid, functional parts. Unlike filament-based (FDM) or resin-based (SLA) printing, SLS prints don’t require support structures, because the unsintered powder naturally supports the model as it’s built.
This makes 3D print SLS technology ideal for creating durable, complex prototypes and low-volume end-use components with industrial-level precision.
What is SLS in 3D printing?
SLS (Selective Laser Sintering) refers to a 3D printing process that selectively sinters powdered thermoplastics — such as PA12 or PA11 — using a laser beam.
Unlike SLA or FDM, SLS prints:
- don’t require supports,
- allow for fully enclosed internal geometries,
- enable nested parts and assemblies in a single print job.
In short, SLS printing gives designers unmatched freedom while delivering functional strength and precision.
How does SLS printing work?
Here’s a simplified step-by-step of the SLS 3D printing process:
- a thin layer of polymer powder is spread across a heated build platform;
- a laser selectively sinters the cross-section of the part;
- the platform lowers, and a new layer of powder is added;
- the process repeats layer by layer until the entire part is built;
- the part is removed from the powder cake and depowdered.
This method delivers parts with excellent mechanical properties, dimensional accuracy, and design complexity.
What is an SLS printer?
An SLS printer — also called an SLS printing machine — is a professional-grade 3D printer designed to handle powdered materials like PA12, PA11, or flexible TPUs. It consists of a powder management system, recoating blade, laser scanning system, and a temperature-controlled build chamber. SLS printers come in various sizes, from compact benchtop models to large-format industrial systems.
They are widely used in sectors such as automotive, aerospace, consumer electronics, and medical device manufacturing.
Can SLS print metal?
Standard SLS printers do not print metal, but the concept is similar.
DMLS (Direct Metal Laser Sintering) and SLM (Selective Laser Melting) are metal-compatible processes that belong to the powder bed fusion family, just like SLS.
While 3D print SLS is specific to thermoplastics, the underlying principle — selective fusion of powder via laser — is also used in metal 3D printing, just with different materials and much higher temperatures.
SLS 3D printing diagram (visual explanation)
A typical SLS 3D printing diagram would include the following components:
- powder feed system,
- recoating blade,
- build platform,
- laser scanning unit,
- heated chamber,
- powder bed.
The diagram helps visualize how each layer is selectively fused by the laser within the bed of powder, and how the part is later removed from the unsintered surroundings.
Why choose SLS printing?
SLS offers a unique combination of material performance, design freedom, and production-grade results. It’s one of the few 3D printing technologies capable of producing complex, durable, and precise parts without any support material—making it both efficient and cost-effective for small to medium batch production.
Whether you’re developing functional prototypes, spare parts, or end-use components, SLS 3D printing technology gives you industrial capabilities in a compact, additive workflow.
SLA vs SLS 3D printing – key differences
While both SLA and SLS are considered high-precision 3D printing technologies, they differ significantly in materials, applications, and operational needs. SLA (Stereolithography) uses a light source to cure liquid resin into highly detailed parts with smooth surfaces, making it ideal for visual prototypes, dental models, and intricate designs. SLS on the other hand, works with powdered thermoplastics to produce strong, functional parts with excellent mechanical properties—without requiring support structures. SLA is best suited for aesthetic and small-scale applications, while SLS excels in industrial-grade, performance-driven use cases where strength and durability are key.
| Feature | SLA (Stereolithography) | SLS (Selective Laser Sintering) |
|---|---|---|
| Material type | Liquid photopolymer resin | Thermoplastic powder (e.g., PA12, PA11) |
| Support structures | Required | Not required (powder acts as support) |
| Surface finish | Very smooth | Matte, slightly rough |
| Detail and resolution | Extremely high (excellent for fine features) | High, but slightly less detailed than SLA |
| Mechanical strength | Moderate | High (suitable for functional parts) |
| Post-processing | Requires cleaning and UV curing | Requires depowdering |
| Design freedom | Limited by support requirements | Excellent (supports complex and nested geometries) |
| Best for | Prototypes, dental, jewelry, visual models | Prototypes, end-use parts, mechanical components |
| Printer maintenance | Medium (resin handling and cleaning) | Higher (powder handling, temperature control) |
| Common industries | Dental, medical, design, education | Aerospace, automotive, consumer products, engineering |
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