Stereolithography (SLA) Providers
Stereolithography cures liquid photopolymer resin with a UV laser to produce parts with exceptional surface finish and fine feature resolution. SLA is the go-to process for visual prototypes, master patterns for casting, and dental or jewellery models requiring smooth surfaces. Find verified SLA providers on ForgedLink with capabilities spanning standard, tough, flexible, and castable resins.
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How Stereolithography works
SLA is the original additive manufacturing process — patented in 1984 by Chuck Hull, who went on to found 3D Systems. A UV laser is steered by galvo mirrors across the surface of a vat of liquid photopolymer resin, selectively curing each layer. After a layer completes, the build platform lifts (or lowers, on "top-down" systems), a fresh layer of resin flows across, and the next layer cures onto the last. Layer thicknesses of 25–100 µm are typical, with XY resolution determined by the laser spot size (50–150 µm on industrial systems).
The result is the finest surface finish and sharpest feature resolution in polymer AM — transparent resin parts come off the printer nearly optically clear, and features down to ~100 µm wall thickness are routine. Parts emerge "green" (partially cured) and need a solvent wash (IPA or proprietary cleaner) to remove uncured resin, followed by a UV post-cure cycle to reach full mechanical properties. Post-cured SLA parts are isotropic, dimensionally stable, and — depending on resin chemistry — suitable for applications from dental models to engineering prototypes to biocompatible medical devices.
Common SLA applications
Dental models, surgical guides, and temporary crowns
The dominant use case. Digital dentistry — intra-oral scan → CAD → SLA print — has replaced stone models in thousands of labs globally. Biocompatible resins (Class I and Class IIa) are qualified for surgical guides and temporary restorations.
Jewellery castable patterns
Castable resins burn out cleanly in investment-casting flasks, leaving no ash. Used by jewellery designers and manufacturers for rings, pendants, and one-off pieces — replacing the wax-carving and wax-injection steps of traditional casting.
Visual and marketing prototypes
The smooth as-printed surface and ability to print transparent or translucent parts makes SLA the go-to process for client-facing concept models, product visualisation, and photography props.
Microfluidic devices and lab-on-a-chip
High-resolution SLA prints fine internal channels (down to ~100 µm) with optical clarity, enabling rapid-iteration microfluidic research without traditional clean-room lithography.
Master patterns for silicone moulds
Smooth SLA masters used to cast silicone RTV moulds for vacuum-casting production runs of 10–50 polyurethane replicas — a standard bridge to injection moulding.
Hearing aids and audiology shells
Custom-fit in-ear device shells from ear-canal scans, printed in biocompatible resins. Millions of hearing aid shells per year are now produced by SLA.
Materials commonly processed by SLA
Standard / General-Purpose Resins
The default visual-prototype material — white, grey, or clear. Good surface finish, moderate strength (30–50 MPa tensile), brittle. Suited to form-and-fit models and non-load-bearing parts.
Tough and Durable Resins (ABS-like, PP-like)
Higher impact strength and elongation for functional prototypes. Formlabs Tough 2000, 3D Systems Accura Xtreme, and Henkel / Loctite tough grades simulate injection-moulded ABS or polypropylene within typical use-life windows.
Castable Resins (Jewellery, Dental)
Wax-like or polymer-wax blends that burn out cleanly in investment-casting flasks. Standard for fine jewellery, dental crown patterns, and precision-casting prototypes.
Flexible / Elastic Resins
Shore 50A–80A photopolymers for gaskets, soft-touch parts, and wearable-device prototypes. Not as durable as SLS TPU but faster and higher-resolution.
Biocompatible and Dental Resins
Class I (short-term skin contact), Class IIa (temporary mucosal / dental, up to 30 days) — Formlabs Dental LT Clear, SG Surgical Guide, IBT. Qualified under ISO 10993 and 93/42/EEC MDR where applicable.
High-Temperature and Engineering Resins
Heat-deflection temperatures of 200–300°C for mould prototyping, thermal-test fixtures, and composite layup tooling. Examples: Formlabs Rigid 10K, 3D Systems Accura AMX Rigid Black, PerFORM from 3D Systems.
Ceramic-Filled and Reinforced Resins
Rigid glass-filled or ceramic-filled resins (Rigid 4000, Rigid 10K, Accura CeraMAX) for dimensionally stable fixtures and high-stiffness parts.
When to choose SLA over DLP, MSLA, MJF, or injection moulding
SLA vs DLP: SLA (laser-based) maintains constant XY resolution across any build area — so a 300 mm print holds the same 100 µm detail at the centre as at the corner. DLP (projector-based) exposes each pixel of a fixed DMD chip, so XY resolution scales inversely with build area — a DLP print at small build area gives finer detail than SLA, but scales down as builds get larger. Choose SLA for large parts that need consistent fine detail; DLP for small-to-mid parts where per-build speed matters.
SLA vs MSLA: SLA industrial systems (3D Systems ProX / SLA 750, Formlabs Form 4L, UnionTech RSPro) produce dimensionally tighter parts with broader resin compatibility than MSLA. MSLA (LCD-masked) gives much cheaper per-machine cost but tighter XY limits and shorter LCD life. For production-grade work, industrial SLA is the default; for hobby / low-stakes prototyping, MSLA wins on economics.
SLA vs MJF / SLS: SLA gives better surface finish and finer features; MJF / SLS give tougher, more isotropic parts in engineering thermoplastics. For visual prototypes, dental / jewellery, and detail-heavy parts, SLA wins. For functional prototypes, end-use polymer production, and load-bearing parts, MJF / SLS win.
SLA vs injection moulding (for prototyping): SLA is the default pre-tooling prototype route for parts smaller than ~300 mm. Below ~100 prototype iterations, SLA is strictly cheaper and faster than soft-tooling. Above that, silicone-mould vacuum casting or aluminium prototype tooling becomes more economic.
Lead time and cost expectations for SLA
Standard SLA parts typically deliver in 2–5 working days from order — including build, wash, post-cure, and support removal. Rush 24-hour services are widely available at a premium. Large-format builds (Form 4L, ProX 950, RSPro 800) can take 12–24 hours of machine time for a fully packed build.
Indicative pricing for a 50 cm³ SLA part (single, standard resin, supported): £40–£90 / €48–€105. Per-part cost drops sharply at volume — 20 nested parts in a single build can cut per-unit cost by 50–70%. Biocompatible and high-temperature resins run 2–3× standard pricing; castable resins 1.5–2×. For dental / jewellery production, per-part economics frequently beat traditional wax-pattern workflows even at modest volumes.
Related processes & materials
Frequently asked questions
What is the difference between SLA, DLP, and MSLA?
All three are vat-photopolymerisation processes — they cure liquid resin with UV light. SLA uses a <strong>laser</strong> traced across each layer; DLP uses a <strong>digital projector</strong> (DMD chip) to expose an entire layer at once; MSLA uses an <strong>LCD screen as a dynamic mask</strong> in front of a UV light array. SLA gives the most consistent XY detail at large build areas; DLP is fastest on small-mid parts; MSLA is cheapest per machine and dominates hobby / prosumer markets.
Do SLA parts need post-curing?
Yes — always. Parts come off the printer in a "green" state where the resin is only partially cured. A full UV post-cure cycle (typically 5–60 minutes depending on resin and part thickness) is required to reach full mechanical properties. Biocompatible and dental resins have specific validated post-cure protocols that must be followed to maintain regulatory status.
Are SLA parts UV-resistant?
Standard photopolymer resins degrade under prolonged UV exposure — they yellow, become brittle, and lose tensile strength. For outdoor or UV-exposed applications, choose UV-stabilised resins (Formlabs Clear V4 with UV block additives, 3D Systems Accura ClearVue, specific outdoor-rated industrial grades) or paint parts with UV-blocking topcoats. For most indoor applications, UV degradation is not a practical issue.
What tolerances are achievable with SLA?
Typical industrial SLA tolerance is ±0.1 mm or ±0.1% of the dimension, whichever is greater. High-resolution systems (Formlabs Form 4, 3D Systems ProX 800) reach ±0.05 mm on well-controlled features. Surface roughness is typically 1–5 µm Ra — the finest of any polymer AM process.
Can SLA parts be used for medical devices?
Yes — for non-implantable and short-term applications. Biocompatible SLA resins are qualified under ISO 10993 for Class I (skin contact, typically ≤24 hours) and Class IIa (mucosal contact up to 30 days, or skin contact up to 30 days). Standard uses include surgical guides, dental models, temporary crowns, and custom audiology shells. For implantable applications, SLA is not the right route — specialised medical-grade PEEK, PCL, or titanium processes apply instead.
Why do SLA parts smell, and is it safe?
Uncured photopolymer resin has a characteristic acrylic smell and can cause skin irritation on contact. After a proper wash-and-post-cure cycle, well-cured parts are inert and safe to handle. Providers operate with gloves, nitrile-compatible workflows, and ventilation during handling; end customers typically receive post-cured, washed parts that can be handled normally.