Selective Laser Sintering (SLS) Providers
Selective Laser Sintering uses a CO₂ laser to sinter powdered polymer — typically nylon PA12 — into solid parts without support structures. SLS produces strong, isotropic parts suited to functional prototyping, end-use production, and complex geometries. Its support-free process enables nested builds for higher throughput. Find SLS providers on ForgedLink verified for powder management, mechanical consistency, and finishing capabilities.
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How Selective Laser Sintering works
SLS is a polymer powder bed fusion process. A CO₂ laser (or, on newer platforms, a fibre laser) selectively fuses thin layers of polymer powder — most commonly nylon PA12 — inside a heated build chamber held just below the powder's melting point. The unmelted powder around each part acts as a self-supporting cake, so SLS builds need no support structures: parts can be nested freely throughout the build volume, even with overhangs, undercuts, internal cavities, or interlocking assemblies.
This support-free nesting is what makes SLS economical for low- and mid-volume polymer production. A single 14-litre build can hold hundreds of small functional parts; a large industrial system (EOS P 770, 3D Systems sPro 230) can fit thousands. After the build, parts are cooled inside the powder cake (typically 24–36 hours to avoid warpage), depowdered, media-blasted, and optionally dyed, vapour-smoothed, or finish-machined. Mechanical properties are essentially isotropic — there is no weak-axis layer-bonding penalty as there is in FDM — which is the second reason SLS is chosen for functional and end-use parts.
Common SLS applications
Functional prototypes in production-equivalent material
PA12 prototypes that mirror the mechanical behaviour of injection-moulded production parts, used for design verification, regulatory testing, and pilot trials before tooling commitment.
End-use polymer parts for consumer, medical, and industrial products
Custom hearing aids, prosthetic sockets, orthotics, drone bodies, robotics housings, and aftermarket automotive components — typically in volumes of 10 to 10,000 units per year.
Jigs, fixtures, and manufacturing aids
Production-floor tooling — assembly jigs, inspection fixtures, end-of-arm tooling, soft-grip robotics — produced in days rather than weeks of CNC machining.
Complex air ducting and ventilation
Single-piece air ducts, manifolds, and ventilation housings that consolidate moulded multi-part assemblies, used in aerospace cabins, motorsport, and HVAC.
Replacement and obsolete parts
On-demand replacement of out-of-production polymer parts — appliance components, vehicle interior trim, industrial equipment — without re-tooling.
TPU flexible parts (gaskets, grips, dampers)
Elastomeric SLS in TPU 70A / 88A produces gaskets, vibration dampeners, soft-touch grips, and wearable device components with rubber-like behaviour.
Materials commonly processed by SLS
Nylon PA12 (PA2200, DuraForm PA, EOS PA 2200)
The default SLS material. Strong, chemically resistant, dimensionally stable, and the most thoroughly characterised polymer in the powder bed fusion world. Default for functional prototypes and end-use parts.
Nylon PA11
Bio-derived nylon with higher impact strength and elongation than PA12. Preferred for snap-fits, living hinges, and parts that need to absorb impact without brittle fracture.
Glass-Filled Nylon (PA12-GF, PA3200)
PA12 with 30–50% glass beads for higher stiffness and dimensional stability. Used for fixtures, brackets, and parts where deflection under load matters.
Carbon-Filled Nylon (PA12-CF)
Short-carbon-fibre-reinforced PA12 for high-stiffness, low-weight applications — drone frames, brackets, automotive aero components.
TPU (Thermoplastic Polyurethane, 70A–95A)
Flexible elastomeric SLS for gaskets, dampers, soft-touch grips, footwear midsoles, and wearable device components.
PA6, polypropylene, PEEK / PEKK
Specialty SLS materials for higher-temperature service (PEEK / PEKK), chemical resistance (PP), or stiffness (PA6). Available on a smaller subset of provider machines.
When to choose SLS over MJF, FDM, or injection moulding
SLS vs MJF: the closest comparison. MJF (HP's Multi Jet Fusion) is faster on per-part basis and gives slightly better surface finish and dimensional accuracy on a typical build. SLS has a wider material range (TPU, PA11, PEEK / PEKK, glass-filled grades) and is supported by a much broader provider network globally. For PA12 production at volume, MJF often wins; for material flexibility, SLS wins.
SLS vs FDM: SLS gives isotropic mechanical properties (no weak Z-axis), no support marks (free-form geometry), and finer feature resolution. FDM is cheaper for single large parts, supports more material types (PEEK, ULTEM, ESD-safe), and is better for very large parts that exceed SLS build envelopes. For functional small-to-mid parts, SLS almost always produces a better part.
SLS vs injection moulding: SLS becomes economic against injection moulding when volume is below ~5,000 units per year, geometry is too complex for tooling, or design iteration is still active. Above that, injection moulding wins on per-part cost — but the tooling investment (£10k–£100k+) and 8–16 week tooling lead time are substantial.
Lead time and cost expectations for SLS
Standard PA12 SLS parts typically deliver in 5–10 working days from order, including build, cool-down, depowdering, and media-blasting. Add 2–5 days for dyeing or vapour smoothing, and 3–7 days for finish-machining of mating features. Rush services (3-day or 24-hour) are widely available at a premium.
Indicative pricing for a 50 cm³ PA12 part (single, media-blasted): £25–£45 / €30–€55 at 1 unit, dropping to £8–£15 / €10–€18 at 100 units as builds nest more efficiently. TPU and carbon-filled grades run roughly 1.5–2× standard PA12 pricing. Compared to injection moulding, SLS becomes uneconomic above ~3,000–5,000 units per year for typical part geometry.
Related processes & materials
Frequently asked questions
How is SLS different from MJF?
Both are nylon powder bed processes. SLS uses a laser to sinter the powder layer by layer; MJF (HP's Multi Jet Fusion) jets a fusing agent across the layer and then fuses the entire layer with infrared lamps in a single pass. MJF is typically faster per build and gives slightly better surface finish. SLS has a wider material range — TPU, PA11, PEEK, glass- and carbon-filled grades — and a much larger global provider network.
Do SLS parts need supports?
No — this is the process's defining advantage. The unmelted powder cake around the part supports overhangs, undercuts, and internal cavities throughout the build. Parts can be nested freely throughout the build volume, including stacking and interlocking, with no support structures to remove afterwards.
What surface finish should I expect from SLS?
As-built SLS surfaces are slightly grainy with a matte finish — typically 8–12 µm Ra, similar in feel to a sandblasted moulded part. Standard post-processing is media blasting for a clean uniform surface; for smoother finishes use vapour smoothing (chemical reflow, glossy finish), dyeing (uniform colour throughout the part wall), or vibratory tumbling (light polish on convex surfaces).
Are SLS parts watertight?
As-built PA12 parts have ~3–5% inherent porosity and are not pressure-tight. For watertight applications, parts can be vapour smoothed (which seals the surface), epoxy-sealed, or specified in MJF instead (which produces denser parts as-built). For most splash-resistant applications and IPx4-class enclosures, as-built SLS is sufficient.
Can SLS parts be coloured?
Yes — most SLS providers offer dyeing in standard colours (black is the most consistent; reds, blues, yellows are available) by immersing parts in heated dye baths after the build. The dye penetrates 0.5–1 mm into the part wall, so surface scratches don't expose white powder. For bulk colour or custom Pantone matches, MJF parts can be painted, and CLIP / DLP processes offer better colour-accurate options.
How accurate are SLS parts?
Typical SLS dimensional tolerance is ±0.3 mm or ±0.3% of the dimension, whichever is greater. Critical dimensions can be tightened by post-process CNC machining of mating features. Repeatability across builds is generally better than ±0.2 mm for well-controlled providers running calibrated machines and qualified powder refresh ratios.