| HS Code | 880748 |
| Tensile Strength | 50 MPa |
| Tensile Modulus | 2,700 MPa |
| Elongation At Break | 4% |
| Flexural Strength | 85 MPa |
| Flexural Modulus | 2,800 MPa |
| Notched Izod Impact Strength | 18 J/m |
| Hardness | 87 Shore D |
| Heat Deflection Temperature At 0 45 Mpa | 120 °C |
| Heat Deflection Temperature At 1 82 Mpa | 80 °C |
| Density | 1.12 g/cm³ |
| Viscosity | 250 cps at 30 °C |
| Critical Exposure | 11 mJ/cm² |
| Penetration Depth | 0.15 mm |
| Dielectric Constant | 3.3 at 1 MHz |
| Dielectric Strength | 15 kV/mm |
| Water Absorption | 0.35% |
As an accredited 3D Systems Accura SI 40 Plastic for the SLA 250 System factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | One opaque, light-blocking plastic bottle with a secure screw cap, packaged individually in a single carton for safe shipping. |
| Container Loading (20′ FCL) | 20′ FCL container loading for 3D Systems Accura SI 40 Plastic: palletized drums, secured upright, temperature-protected, and labeled per transport regulations. |
| Shipping | 3D Systems Accura SI 40 Plastic for the SLA 250 System ships as a non-regulated, light-sensitive liquid resin. Use opaque, sealed, UN-approved containers. Transport at 15–25°C, away from heat, sparks, and direct sunlight. Not classified as dangerous goods for DOT, IATA, or IMDG. Follow SDS and local regulations. |
| Storage | Store Accura SI 40 in its original, tightly closed container in a cool, dry, well-ventilated area, away from direct sunlight, heat, sparks, and open flames. Maintain manufacturer-recommended temperatures and avoid freezing. Keep separate from incompatible materials, food, and drink. Protect from moisture and physical damage, and keep out of reach of children. Ensure containers are labeled and closed after use. |
| Shelf Life | Shelf life is 12 months from manufacture when stored unopened in original container at 18–25°C, protected from light. |
The industrial application of Accura SI 40 Plastic for the SLA 250 System is confined to liquid photopolymer processing within the SLA 250 platform, where the resin is supplied ready to build and is not a pellet, masterbatch, or compounding feedstock. Storage before use is maintained at 15–30°C, the vat is stirred before filling to avoid viscosity stratification, and exposure to wavelengths below 420 nm outside the build envelope is excluded because unintended photopolymerization alters recoating behaviour. Because the material is a formulated epoxide-based photopolymer, the relevant processing dosage is 100 wt% neat resin in the vat; no downstream thermoplastic compounding ratio applies, and dilution with non-validated reactive diluents is not supported by the SLA 250 optical train or recoating parameters. The five downstream sectors examined below cover expenditure patterns, elastomeric tooling masters, aerodynamic test articles, non-implantable medical visual models, and consumer electronics enclosure prototypes. Each sector is separated by its process-limiting variable and compliance anchor, not by generic application language.
| Application sector | Material dosage in vat | Primary compliance anchor | Dominant boundary condition |
|---|---|---|---|
| Investment casting expendable patterns | 100 wt% neat | AS9100D / ISO 9001:2015 | Burnout thermal expansion stress in ceramic shells |
| Silicone molding master production | 100 wt% neat | ISO 9001:2015 / REACH Regulation (EC) No 1907/2006 | Platinum-cure silicone inhibition on epoxy surfaces |
| Wind-tunnel and motorsport test articles | 100 wt% neat; vat filled 70–80% maximum | ISO 9001:2015 / ISO 2768-1:1993 | Partial-cure sanding heat distortion |
| Medical anatomical models | 100 wt% neat | ISO 13485:2016 / ISO 10993-1:2018 | Sterilization heat above heat deflection temperature |
| Consumer electronics enclosure prototypes | 100 wt% neat | RoHS Directive 2011/65/EU Annex II / ISO 9001:2015 | Anisotropic snap-arm mechanical response |
Accura SI 40 functions as an expendable positive pattern in foundry investment casting because the SLA 250 platform can generate hollow or latticed patterns at a nominal layer thickness of 0.1 mm, permitting wax-free direct-shell processing where traditional wax pattern tooling cannot produce internal drain geometry. The material is loaded at 100 wt% neat photopolymer in the vat; no high-temperature filler, wax modifier, or inorganic burn-out aid is introduced because dispersed particulates scatter the imaging beam and alter the recoat blade gap. The dominant process conflict is shell cracking during thermal burnout, which becomes acute when unperforated thick sections exceed 5 mm or when internal hollow chambers lack open drain apertures of 2–3 mm minimum diameter. Published data for this specific configuration is limited for ash residue below 0.01 wt% TGA detection thresholds, so foundries must validate burnout residue against the shell manufacturer’s thermal schedule rather than assume zero-ash behaviour. Production should operate under AS9100D for aerospace castings or ISO 9001:2015 for general foundry quality, with dimensional acceptance verified on the pattern before shelling. The downstream route includes SLA 250 pattern build, two-stage solvent rinse to remove uncured resin, ambient or heated post-cure, gate and runner attachment, ceramic slurry coating in 7–8 layers, autoclave dewax, flash-fire burnout from 600–800°C, and controlled metal pouring. Terminal components are low-volume investment-cast aluminium, stainless steel, and cobalt-chromium articles such as pump housings, inlet manifolds, turbine blade surrogate shapes, and structural brackets.
Vacuum casting and silicone mold-making operations use Accura SI 40 as a positive master produced at 100 wt% neat resin in the SLA 250 vat, with no reactive diluent added to the photopolymer. The critical compatibility boundary is that epoxy-based SLA master surfaces can inhibit platinum-catalysed addition-cure RTV silicone; if cure inhibition cannot be tolerated, the master must be sealed with a chemically compatible barrier coat or a tin-cure condensation silicone must be selected. The governing process standard is ISO 9001:2015 for pattern dimensional control, with form and position tolerances managed under ISO 1101:2017 where the customer drawing requires. Material handling and downstream export documentation fall under REACH Regulation (EC) No 1907/2006, and the RoHS Directive 2011/65/EU Annex II may apply when the final cast component is integrated into electrical equipment. The downstream production flow includes SLA 250 build at 0.1 mm layer thickness, support removal, solvent rinse, post-cure, surface filling, and polishing to Ra 0.8 µm or finer before boxing. The silicone mold itself is separately mixed at a 10:1 base-to-catalyst weight ratio; this ratio belongs to the mold rubber and is independent of Accura SI 40 dosage. Vacuum casting of two-part polyurethane then yields 10–30 functional copies per mold, depending on exotherm and cavity geometry. Terminal outputs are low-volume polyurethane covers, gaskets, overmolding trials, and enclosures for pre-production industrial and consumer equipment.
Wind-tunnel and motorsport test article fabrication imposes a surface finish and dimensional tolerance requirement that cannot be satisfied by a single post-cure protocol; therefore, Accura SI 40 is processed in the SLA 250 at 100 wt% neat, with the vat filled to 70–80% of maximum working level to reduce recoat blade air entrainment and resin vortexing. The principal process conflict is that dry sanding of partially post-cured surfaces generates local frictional heat sufficient to warp thin trailing edges; parts must reach full post-cure conversion before sanding at 320–400 grit. Compliance documentation for external aerodynamic test components is structured under ISO 9001:2015 and ISO 2768-1:1993 for general tolerances, while tensile and flexural properties are verified per ASTM D638-14 and ASTM D790-17 on the production batch. The production chain includes SLA 250 build at 0.1 mm layer thickness, solvent rinse, post-cure, epoxy filler application for stair-stepping removal, dry sanding, primer, and topcoat applied at a wet-film paint thickness of 20–50 µm to avoid dimensional drift. Terminal products are wind-tunnel models, wing-body fairing test pieces, sensor housing arrays, and fixture arms exposed to aerodynamic load at room temperature; thermal service above the resin’s heat deflection temperature is not recommended without published thermomechanical data for the specific lot.
Medical device anatomical models and surgical planning outputs can be produced from Accura SI 40 on the SLA 250 only when the material lot is reviewed against ISO 10993-1:2018 for the intended contact category. The base resin is not automatically USP Class VI certified, and published data for this specific configuration is limited; therefore, a hospital or device developer must not assume biological evaluation acceptance without a written supplier certificate. The processing dosage is 100 wt% neat photopolymer in the vat; no antimicrobial, radiopaque, or biological additive is introduced because the SLA 250 imaging and recoat parameters are not validated for particle-loaded formulations. Production under ISO 13485:2016 requires DICOM-derived STL files to be inspected for non-manifold edges, enclosed voids, and wall thickness before build. The SLA 250 then builds at 0.1 mm layer thickness, followed by solvent rinse, post-cure, and separate colour coding or painting after full cure. The institutional process boundary is that autoclave sterilization above the resin’s heat deflection temperature can cause dimensional drift and surface degradation; models intended for sterile-field use must be evaluated under the hospital’s sterilization validation rather than through accelerated bench heating alone. Terminal products are surgical planning replicas, education models, and non-implantable anatomical review tools used outside direct patient-contact use unless the facility has completed the relevant ISO 10993 evaluation.
Snap-fit endurance testing on Accura SI 40 enclosure prototypes requires the SLA 250 laboratory to control post-cure conversion because undercured sections exhibit low flexural modulus and premature snap-arm fracture. The material is used at 100 wt% neat resin in the vat, with no polycarbonate, ABS, or impact-modifier addition because the photopolymer is thermoset and cannot be melt compounded. The compliance anchor for electronic prototype enclosures is RoHS Directive 2011/65/EU Annex II for restricted substances, together with ISO 9001:2015 for prototype dimensional control. Mechanical characterisation for snap-fit deflection can reference ASTM D790-17 and ASTM D256-10, although SLA-generated samples are anisotropic and must be built in an orientation matching the intended assembly loading. The downstream production route includes SLA 250 build, solvent rinse, post-cure, threaded insert installation by heat-set or adhesive methods with local temperature held below the resin heat deflection temperature, snap-arm deflection testing at 0.5–2.0 mm engagement, and cyclic fit validation for 50–200 assembly events depending on the OEM protocol. Terminal products are mobile device housing test fixtures, display bezel prototypes, battery cover fit-check models, and connector assembly jigs. Creep, moisture uptake, and repeated insertion performance should be established from the resin manufacturer’s published batch data, not from general-purpose amorphous thermoplastic reference values.
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3D Systems Accura SI 40 Plastic for the SLA 250 System is a solvent-free acrylate photopolymer formulated for the legacy SLA 250 vat photopolymerization platform operating with a 325 nm helium–cadmium source. The resin is not a direct substitute for 355 nm solid-state laser grades; its photoinitiator response, working curve, and green-state recoating behavior are tuned to the SLA 250 optical train and elevator assembly. The platform provides a build envelope of 250 mm × 250 mm × 250 mm, a nominal laser output near 40 mW, and a focused beam diameter of approximately 0.25 mm. These values interact with cure depth and critical exposure, so processing parameters cannot be transferred from newer Accura materials without revalidation. Application notes list the product for functional prototypes, silicone tool master patterns, and short-run rigid components when acceptance is based on tensile and flexural data generated under ASTM D638-14 and ASTM D790-17.
The liquid material is supplied at a density near 1.12 g/cm³ and a viscosity that supports heated-vat recoating; typical values fall between 900 mPa·s and 1200 mPa·s at 30 °C. The product is protected from light in the 300 nm to 420 nm band and stored at 20 °C to 25 °C. Low-shear stirring is specified before transfer to the vat because high-shear mixing entrains microbubbles that appear later as sub-surface voids. No mineral, glass, or ceramic filler is specified in the standard product literature; the absence of fillers reduces sedimentation but places stricter limits on recoat blade speed and vat temperature. Water absorption and dissolved oxygen in the vat must be controlled because both degrade radical polymerization efficiency.
The cure depth for a single laser pass is governed by the relationship Cd = Dp ln(E/Ec), where Cd is cured depth, Dp is penetration depth, E is applied exposure, and Ec is critical exposure. Historical SLA 250 application data for Accura SI 40 give Dp on the order of 0.15 mm and Ec near 10.5 mJ/cm² on the 325 nm emission line. These values are not static in production. Dissolved oxygen consumes photoinitiator radicals and raises Ec by 10 % to 15 % after repeated recoating cycles; photoinitiator depletion in shallow vats produces further positive drift. Without scanner compensation, a raised Ec yields a cured line shallower than the programmed layer thickness, causing interlayer delamination, under-cured sidewalls, and negative z-axis dimensional error. The accepted countermeasure on the SLA 250 is to raise border overcure from 0.05 mm to 0.08 mm and to hold hatch spacing between 0.08 mm and 0.12 mm. Because the exact shift depends on vat age, oxygen partial pressure, and resin lot, controlled processes should include a working curve coupon at the start of each production batch. Published lot-specific working curve data for current Accura SI 40 supplies are limited; the operator should obtain the material certificate from 3D Systems or determine Dp and Ec empirically.
Optical path contamination introduces a separate source of exposure loss. The SLA 250 uses galvanometer mirrors and a quartz window; any haze reduces delivered power at the vat surface. A power drop of 5 % from the nominal 40 mW is usually compensated by increasing laser pass energy, but a drop exceeding 10 % requires optical cleaning or beam realignment. The logarithmic dependence of cure depth on exposure means that small power losses are amplified when Ec approaches the upper end of its lot range.
Recoating is the dominant process risk for Accura SI 40 on the SLA 250. The resin must form a uniform film over the previously cured layer before each scan. Manufacturer guidance specifies a vat temperature of 28 °C to 32 °C, equivalent to a narrow ±2 °C window around the standard 30 °C setpoint. At 26 °C or below, viscosity rises and the recoat blade can skip over the surface, leaving horizontal striations. Above 34 °C, dark polymerization may progress too quickly and produce unwanted gelation at the vat walls. At a layer thickness of 0.05 mm, the skip defect is more likely because the thin layer provides less tolerance for incomplete wetting. For functional prototypes, Accura SI 40 is generally processed at 0.10 mm or 0.15 mm; the 0.10 mm setting is preferred when snap-fit arms, ribs, or fine sidewall features must be resolved. The recoat pause after elevator lowering is typically set between 2 s and 10 s. An excessively long pause allows residual radicals to polymerize in the dark, while an excessively short pause entrains air at the underside of the new layer and creates bubble defects. Batch-to-batch viscosity drift should be checked against the certificate of analysis; values above 1200 mPa·s at 30 °C indicate that the vat heater may not maintain a stable recoat layer.
On actual SLA 250 lines, horizontal striations are often misdiagnosed as laser power failure. The more common cause is insufficient recoat delay after the elevator step. The operator should record striation spacing and correlate it with vat temperature before changing scan parameters. Support removal before post-cure rather than after can reduce fracture at contact points because the green polymer is softer. The platform is drained over the vat for 15 min to 30 min to recover liquid resin and reduce wash-solvent contamination.
Mechanical property conformance begins with standardized specimen builds and conditioning. Tensile tests are conducted according to ASTM D638-14 using Type I specimens; flexural tests follow ASTM D790-17 at 2 mm/min; notched Izod impact is measured with ASTM D256-10; heat deflection temperature is evaluated at 0.45 MPa and 1.82 MPa using ASTM D648-16; density is determined by ASTM D792-20. The table below lists the standard methods and specimen conditions normally referenced for this product.
| Property | Method | Specimen condition |
|---|---|---|
| Viscosity, liquid | ISO 2884-1:1999 | 30 °C, spindle viscometer |
| Tensile modulus, strength, elongation | ASTM D638-14 | Type I, 5 mm/min, 23 °C ± 2 °C |
| Flexural modulus, strength | ASTM D790-17 | Three-point, 2 mm/min |
| Izod impact | ASTM D256-10 | Notched, 23 °C ± 2 °C |
| Heat deflection temperature | ASTM D648-16 | 0.45 MPa and 1.82 MPa, edgewise |
| Density | ASTM D792-20 | Displacement method, 23 °C |
Within this product class, supplier-published values for Accura SI 40 typically place tensile modulus between 2.4 GPa and 2.8 GPa, tensile strength between 58 MPa and 65 MPa, and elongation at break between 4 % and 8 %. Flexural strength is generally reported between 80 MPa and 95 MPa, and notched Izod impact between 18 J/m and 25 J/m. Heat deflection temperature at 0.45 MPa is commonly reported in the 58 °C to 64 °C band. These values are class-level and orientation-dependent; they are not design allowables for a specific SLA 250 build unless revalidated with the actual batch, layer thickness, and post-cure cycle. Published data for fatigue, creep, and long-term environmental aging of this specific SLA 250 formulation is limited.
Green parts are rinsed in tripropylene glycol monomethyl ether or isopropyl alcohol to remove uncured liquid resin. Isopropyl alcohol immersion should not exceed 24 h; prolonged soaking swells the green polymer network and rounds sharp edges. Post-curing is typically performed under UV-A lamps at a surface temperature not exceeding 60 °C for 60 min. Higher post-cure temperatures can relieve internal stresses unevenly and distort thin walls, while under-cured parts retain unreacted monomer that lowers modulus and can produce a tacky surface. After post-cure, conditioning at 23 °C ± 2 °C and 50 % ± 10 % relative humidity for 24 h is specified before mechanical testing. Direct contact with ketone solvents, strong acids, or strong bases is an operational boundary; these media can swell or degrade the ester linkages in the acrylate network. The material is not recommended for continuous service above its documented heat deflection temperature. For elevated-temperature structural use, creep testing under ASTM D2990-17 or equivalent should be conducted, but published data for this specific configuration is limited.
A documented incompatibility occurs with platinum-catalyzed addition-cure silicone systems. Residual unreacted acrylate at the part surface can inhibit curing when Accura SI 40 master patterns are used for silicone toolmaking unless the pattern is post-cured and sealed with a barrier coat or release system. Regulatory status under REACH, RoHS, and FDA 21 CFR 177 must be confirmed with the supplier; the standard material datasheet does not establish food-contact or medical-device compliance.
Differences from other Accura resins are defined first by laser compatibility. Accura SI 40 is matched to the 325 nm HeCd source of the SLA 250; Accura 25, Accura 60, and Accura Xtreme are supplied for 355 nm solid-state platforms. In property class, Accura SI 40 is a rigid acrylate with moderate elongation; Accura 25 is a polypropylene-like material with lower modulus and higher elongation; Accura 60 is a clear polycarbonate-like material with higher modulus and lower impact tolerance; Accura Xtreme is an ABS-like material with higher impact tolerance. Table 2 summarizes this qualitative positioning.
| Attribute | Accura SI 40 | Accura 25 | Accura 60 | Accura Xtreme |
|---|---|---|---|---|
| Primary laser line | 325 nm | 355 nm | 355 nm | 355 nm |
| Property class | Rigid acrylate, moderate elongation | Polypropylene-like, higher elongation | Clear polycarbonate-like, higher modulus | ABS-like, higher impact |
| Typical use boundary | SLA 250 legacy builds; moderate thermal load | Snap-fit assemblies; low-modulus housings | Transparent fluidic prototypes | Impact-resistant enclosures |
For SLA 250 process planners, Accura SI 40 is selected when the part must be built on the HeCd platform and the mechanical load case falls within the rigid, moderate-elongation envelope. If higher impact resistance is required, Accura Xtreme is used only on validated 355 nm equipment; if polypropylene-like ductility is required, Accura 25 is selected after design verification in the target build orientation. Differences in laser dose, recoat behavior, and shore hardness should not be ignored.
