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3D Systems FabPro™ Elastic BLK Elastomer

    • Product Name: 3D Systems FabPro™ Elastic BLK Elastomer
    • Factroy Site: Yudu County, Ganzhou, Jiangxi, China
    • Price Inquiry: admin@ascent-chem.com
    • Manufacturer: Ascent Petrochem Holdings Co., Limited
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    Specifications
    HS Code 316959
    Color Black
    Viscosity At 25 C 850 cP
    Density 1.08 g/cm³
    Shore A Hardness 65
    Tensile Strength 3.0 MPa
    Elongation At Break 120%
    Tensile Modulus 2.8 MPa
    Tear Strength 12 kN/m
    Compression Set 20%
    Rebound Resilience 50%
    Glass Transition Temperature -30°C
    Service Temperature Range -20°C to 80°C

    As an accredited 3D Systems FabPro™ Elastic BLK Elastomer factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.

    Packing & Storage
    Packing 1 kg opaque black plastic bottle with screw cap, labeled 3D Systems FabPro™ Elastic BLK Elastomer for resin handling.
    Container Loading (20′ FCL) Container Loading (20′ FCL): 3D Systems FabPro™ Elastic BLK Elastomer palletized, shrink-wrapped, and secured inside container for compliant ocean transport.
    Shipping 3D Systems FabPro™ Elastic BLK Elastomer ships as a liquid UV-curable resin in sealed, opaque original containers. Transport upright at moderate temperatures, away from UV and freezing. Usually not classified as dangerous goods; follow the SDS, local regulations, leak-proof packaging, and labeling requirements. Ship via approved ground or air carriers.
    Storage Store in the original, tightly sealed container upright in a cool, dry, well-ventilated area. Keep away from direct sunlight, UV light, heat, sparks, flames, and incompatible materials. Maintain recommended temperature, typically 15–30°C, and avoid freezing. Keep closed when not in use, away from food, drink, and children. Protect from moisture and contamination. Follow SDS and local regulations.
    Shelf Life Shelf life is 12 months from manufacture when stored unopened in original packaging at 15–30°C, away from light and moisture.
    Application of 3D Systems FabPro™ Elastic BLK Elastomer
    Soft-touch gripping surfaces overmoulded onto rigid prototypes for handheld analytical instruments are produced with FabPro Elastic BLK elastomer as a single-component photopolymer. The material is printed on a **405 nm** DLP platform at **50 µm** layer thickness. A starting exposure energy of **10–15 mJ/cm²** per layer is typical for this elastomer class; exact values must be derived from greyed exposure tests because pigment opacity reduces available cure depth. The cured material exhibits Shore A hardness in the **60–70A** range and an elongation at break exceeding **100%** when tested according to **ASTM D638-14**. For gripping prototypes, wall thickness is maintained between **2.0 mm** and **4.0 mm** to provide sufficient compression under finger load without exceeding the elastic limit. Adhesion to rigid DLP substrates is limited by the low surface energy of the cured elastomer. Plasma treatment with oxygen at **200 W** for **60 s** raises the polar component of surface tension and improves peel resistance. Peel strength should be verified according to **ASTM D429-14** Method B because no published adhesion data for this specific material combination is available. End-use assembly follows the same fastening points as production two-shot injection moulding. Screw bosses and snap-fit features are reinforced with higher-durometer photopolymer inserts to prevent pull-through. The elastomer portion is designed with a Shore A variation of no more than **±5A** across the part. This variation is influenced by the UV dose gradient between the exposure side and the build platform side. Parts printed with insufficient exposure show lower crosslink density on the back face, which reduces abrasion resistance. A post-cure step at **60°C** for **40 minutes** under **405 nm** illumination raises crosslink density while maintaining elongation. The untreated material may contain trace unreacted monomer after printing. The post-cure also reduces residual surface tack. For skin-contact handheld devices, migration testing per **ISO 10993-23:2021** is recommended, although FabPro Elastic BLK is not supplied as a certified medical-grade resin. **REACH Regulation (EC) No 1907/2006** Article 33 SVHC content should be confirmed through the current safety data sheet before use in European consumer products.

    What Limits Gasket Compression Set in Low-Pressure Fluid Sealing?

    Gasket prototypes for water filter housings and battery enclosures are printed from FabPro Elastic BLK elastomer with the seal surface oriented perpendicular to the print z-axis. This orientation reduces staircase ridges on the sealing lip. The typical operating environment is low-pressure, below **0.5 MPa**, and temperatures not exceeding **50°C**. Under these conditions, the dominant failure mode is compression set, not tensile rupture. Compression set is evaluated according to **ASTM D395-18** Method B at **70°C** for **22 h**. Elastomer photopolymers in the **60–70A** Shore A class frequently exhibit compression set in the **20–40%** range after production post-cure, but published data for FabPro Elastic BLK under full production post-cure is limited. When compression set exceeds **40%**, sealing force at the gland interface drops below the threshold needed to maintain a positive seal during thermal cycling. There is a process conflict: increasing post-cure energy density reduces compression set through higher crosslink density, but also reduces elongation and raises hardness. If post-cure temperature exceeds **65°C**, the part may distort or develop microcracks at stress concentrators such as bolt holes. Therefore the recommended post-cure for gasket geometry is **405 nm** UV at **60°C** for **40 minutes**. A second UV exposure on the reverse face improves through-thickness cure uniformity. Gasket groove design must consider the material's tear resistance. Tear strength is measured according to **ASTM D624-00(2020)** Die C. Because tear strength is typically below **20 kN/m** for this class, sharp groove corners must be avoided. A minimum fillet radius of **0.5 mm** is applied to the gland floor. The printed gasket is assembled in a recess with **20–30%** compression. Lower compression may result in insufficient contact pressure. Higher compression accelerates stress relaxation. The housing components are typically made from glass-filled nylon or polycarbonate. The elastomer must not contain plasticizers that migrate into the polycarbonate and cause stress cracking. Extractables testing per **ISO 6427:2013** is recommended for plasticizer content. For battery enclosure prototypes, **IP67** sealing is verified per **IEC 60529** with a **1 m** submersion for **30 minutes**. The printed gasket passes this test only when the surface is free of support removal artifacts. Supports are placed exclusively on non-sealing faces. The build platform side is not used as the sealing face because air inhibition during printing leaves a slightly tacky, low-crosslink skin. This skin is removed by post-cure or by printing the seal face on the exposure-side.Prototype footwear midsoles and insoles are produced with FabPro Elastic BLK elastomer to evaluate cushioning performance before committing to compression-moulded polyurethane or EVA foam tooling. The material is printed at **50 µm** layer thickness with the flex axis aligned to the x-y plane. This reduces interlayer failure during repeated heel-strike cycling. Tensile properties are measured to **ASTM D638-14**. Typical reported elongation for this class is above **100%**, which supports early-stage flexural fatigue screening. The material is not a substitute for polyurethane foam; its specific energy return and density are significantly different. Therefore midsole prototypes are used only for shape verification and pad fit assessment, not for quantitative cushioning correlation. Printed lattice structures with **3.0 mm** cell size and **2.0 mm** wall thickness provide a controlled compressive modulus gradient across the heel, midfoot and forefoot. The modulus gradient is achieved by varying lattice density within a single print, not by changing material formulation. However, the elastomer's black pigmentation limits optical inspection of internal lattice defects. CT scanning or destructive sectioning is required to confirm no trapped resin pockets. The manufacturer recommends draining uncured resin from enclosed lattice cells through vent holes of at least **1.0 mm** diameter. Without vents, liquid resin remains and creates local mass imbalance. After printing, parts are washed in isopropyl alcohol for **3–5 minutes**. Longer solvent immersion causes measurable swelling and temporary reduction in Shore A hardness. The solvent must be fully evaporated before post-cure. Residual solvent acts as a plasticizer and reduces tensile strength. For insole prototypes, skin contact is short-term and non-clinical. Nevertheless, the final prototype is coated with a water-based silicone barrier to reduce surface tack and improve cleanability. This coating does not affect the durometer beyond **±2A**. Wear testing is performed on a SATRA **TM99** abrasion machine for **500 cycles**. The material exhibits surface abrasion similar to other elastomer photopolymers; published data for this specific configuration is limited. The prototyped midsole is integrated into an upper using adhesive bonding with a two-component polyurethane adhesive. The bond line is designed to fail cohesively within the elastomer, not adhesively at the interface. Peel testing per **ASTM D903-98(2017)** on flat coupons is recommended prior to full assembly.

    Vibration Damping Pucks and Sleeves in Handheld Power Tools

    Electric power tool housings containing brushless motors generate vibration in the **50–200 Hz** range. FabPro Elastic BLK elastomer is formed into cylindrical damping pucks and motor sleeve liners to reduce transmitted vibration to the handle. The effectiveness of the material depends on hardness, wall thickness and crosslink density. Hardness is measured by **ASTM D2240-15** (Type A). The target is **60–70A** for optimal energy absorption in the above frequency range, but dynamic mechanical analysis (DMA) data for this photopolymer is not included in the published datasheet. The absence of tan delta and storage modulus data means that any vibration isolation design must be screened on a DMA instrument at **10 Hz** and **23°C** before printing full tools. Damping pucks are printed as cylinders with **4.0 mm** thickness and **8.0 mm** diameter. The build orientation places the flat piston surfaces horizontal to reduce internal air entrapment. After post-cure at **60°C** for **40 minutes** under **405 nm** UV, the pucks show a hardness increase of **3–5A** compared to non-post-cured parts. This increase reduces damping at low frequency but improves creep resistance. Creep under static load is measured according to **ASTM D2990-17**. At **25°C** and a **0.25 MPa** compressive stress, the elastomer shows measurable creep within the first hour. Published data for FabPro Elastic BLK under these conditions is limited; validation prints must be monitored for **24 h**. The sleeves are printed with a wall thickness of **3.0 mm** and bonded into the motor housing using cyanoacrylate adhesive. Cyanoacrylate adhesive produces a rigid bond line that can crack due to differential thermal expansion. A flexible UV-curable adhesive with an elongation of at least **80%** is specified instead. The adhesive joint is tested by pull-out per **ASTM D1002-10** on aluminium lap shear coupons. Flammability classification for the printed elastomer is not published. For power tools sold in Europe or North America, **UL 94** testing on the final part geometry is required. The material is unlikely to achieve **V-0** due to its organic photopolymer backbone. Therefore the part is designed to be shielded from ignition sources. End products include battery pack isolation mounts, motor seating pads and handle grip liners.

    When the Part Must Be Printed Without Solvent-Assisted Support Removal

    Soft robotic actuators and pneumatic bellows require internal channels that cannot tolerate residual solvent after support removal. FabPro Elastic BLK elastomer is used for these parts because of its elongation above **100%** and its ability to withstand repeated inflation without immediate fatigue cracking. The key process constraint is support removal. Isopropyl alcohol immersion is commonly used to remove uncured resin from small channels, but for elastomeric photopolymers of this Shore A class, solvent immersion beyond **5 minutes** swells the part. The swelling reduces hardness by **10–15%** and can create micro-tears at sharp internal corners. Therefore the support strategy must be designed to allow mechanical breakaway without solvent. Support posts are generated with a contact diameter of **0.2 mm** and a spacing of **1.0 mm** along the part surface. The contact point is placed on the outer surface, not inside channels. After build, supports are removed with side cutters at room temperature. The remaining nubs are sanded with **400-grit** paper. For internal channels below **2.0 mm** diameter, the DLP process may not resolve the cross-section correctly due to light scattering from the black pigmented resin. A minimum channel diameter of **2.5 mm** is applied. The build orientation is set to **30°** from horizontal to reduce the number of enclosed voids. Vent holes of **1.0 mm** are added at the highest point of each chamber to allow air and uncured resin to drain during printing. After support removal, the part is washed in fresh isopropyl alcohol for exactly **3 minutes**, then dried with compressed air. The wash removes any surface residue from broken supports. The part is then post-cured at **405 nm** for **30 minutes** at **60°C**. Longer post-cure increases crosslink density but reduces elongation and increases the risk of pneumatic fatigue failure. The final bellows is tested to **20,000 cycles** at **20 kPa** internal pressure. Failure typically occurs at the layer interface near the neutral axis of bending, not at the support nub. To improve interlayer adhesion, the exposure time per layer is increased by **10–15%** over the manufacturer's default. This increase offsets the light attenuation caused by the black pigment and produces a more uniform conversion profile through the **50 µm** layer. However, over-exposure broadens the layer thickness and can close narrow channels. Therefore a test chip is printed first with a series of channel diameters. The smallest channel that prints cleanly determines the design limit for that resin lot. Lot-to-lot variation in pigment loading can shift the exposure window by **±10%**, so the test chip is repeated for each new material lot.Surgical training models and anatomical simulators are produced by DLP printing FabPro Elastic BLK elastomer for haptic response in the **60–70A** Shore A range. The material is not supplied as a medical-grade resin. However, because the models are non-sterile, non-implantable and used only for training, the manufacturer may evaluate biocompatibility for skin contact per **ISO 10993-5:2009** and **ISO 10993-10:2010**. Cytotoxicity testing is performed on final processed parts, not raw resin, because post-cure and washing alter the leachable profile. The printed parts are washed in isopropyl alcohol and post-cured at **60°C** for **40 minutes** under **405 nm** UV before any biological testing. Residual unreacted monomer can be cytotoxic. A post-cure storage period of **72 h** at **23°C** further reduces volatile content. The material's black pigmentation limits visual haptic realism. For dermal suturing trainers, an outer silicone paint or pigmented coating is required to mimic skin tone. The paint must not exceed a dry film thickness of **50 µm** or it will alter the needle penetration force. Needle penetration force is measured with a universal testing machine at **10 mm/min**. The printed substrate at **5.0 mm** thickness reproduces the two-layer feel of skin and subcutaneous fat when combined with a lower-durometer silicone backer. A silicone backer of Shore OO **00-30** is bonded to the underside. The FabPro Elastic BLK layer is printed at **30 µm** layer thickness to capture fine anatomical features such as vessel walls and tissue folds. At this layer thickness, build time increases significantly. The print station must be temperature-controlled at **25°C ± 3°C** to maintain resin viscosity below **1000 mPa·s**. Viscosity above this range reduces wicking from small features and causes surface defects. The printed model is inspected for voids using a **10X** stereo microscope. Voids larger than **0.5 mm** are rejected. The model is packaged in a low-density polyethylene bag with a desiccant pack. The material absorbs moisture from ambient air at rates above **1%** by mass at **23°C** and **50% RH**; moisture plasticizes the surface and reduces Shore A hardness by up to **5A**. Therefore storage at **20–25°C** and **RH < 50%** is specified.The following compliance matrix consolidates the primary standards and directives cited for each application segment.
    Application SegmentStandard / DirectiveTest Method / ClauseVerification Point for FabPro Elastic BLK
    Consumer electronics soft-touch overmoldRoHS Directive 2011/65/EU; REACH Regulation (EC) No 1907/2006SVHC content; ASTM D429-14 Method BPeel adhesion to rigid substrate confirmed; SVHC confirmed via SDS
    Low-pressure fluid sealing gasketsIEC 60529 IP67ASTM D395-18 Method B; ASTM D624-00(2020) Die CCompression set below threshold; tear strength above gland corner stress
    Footwear midsole prototypesREACH Regulation (EC) No 1907/2006ASTM D638-14; ASTM D903-98(2017)Elongation above 100%; adhesive bond cohesive failure
    Power tool damping partsUL 94 (part geometry)ASTM D2240-15; ASTM D2990-17Hardness 60–70A; creep measured for 24 h
    Soft robotic actuatorsNone specific; internal qualityISO 1817:2015 for solvent; internal pneumatic cycle test20,000 cycles at 20 kPa; no channel occlusion
    Medical training modelsISO 10993-5:2009; ISO 10993-10:2010Cytotoxicity on final parts; irritation on final partsEnd-use not medical grade; user responsible for biological safety
    Automotive wire routing grommetsSAE J1455ASTM D624-00(2020) Die T; ASTM D2136-19Tear above 15 kN/m; low-temperature flex no crack

    Automotive Wire Routing Grommets Exposed to Interior Heat Cycling

    Under-hood and interior wire routing grommets are prototyped in FabPro Elastic BLK elastomer to verify fit before tooling production of EPDM or silicone rubber parts. The printed material is not a substitute for production elastomer; its service temperature range is narrower. Continuous exposure above **80°C** causes progressive hardening and loss of elongation due to continued crosslink formation. The actual heat deflection temperature for this material has not been published. For automotive interior validation, the grommets are cycled between **-20°C** and **60°C** for **100 cycles** following a **2 h** ramp and **1 h** soak profile. The low-temperature cycle is more critical because the elastomer becomes stiffer and may crack when the wire bundle is inserted. Low-temperature flexibility is evaluated by bending at **-20°C** per **ASTM D2136-19** (brittle point). The flexible photopolymer does not exhibit a distinct brittle point above **-40°C**, but published data for this configuration is limited. The grommet design includes a **2.5 mm** wall thickness around the wire bundle exit and a **0.5 mm** interference fit with the sheetmetal aperture. The interference fit is achieved by printed ribs on the outer diameter. Rib height is **0.3 mm** with **45°** draft. This ribbed design allows the same printed part to seal on different sheetmetal thicknesses from **0.8 mm** to **1.5 mm**. During insertion, the grommet is lubricated with a diluted soap solution. The tear resistance at the rib root is evaluated by **ASTM D624-00(2020)** Die T. Because Die T is more sensitive to crack propagation, it is the preferred test for sharp rib intersections. A minimum tear resistance of **15 kN/m** is required at **23°C**. If the printed batch falls below this value, post-cure is extended by **10 minutes**. The part is also exposed to a **10-minute** immersion in **ISO 1817:2015** reference fuel A to screen for swelling. Swelling beyond **5%** by volume indicates insufficient crosslink density and requires process adjustment. The final printed assembly is vibration-tested to **SAE J1455** for **10 hours**. The test is performed on a shaker table at **10–100 Hz** with **1.5 g** peak acceleration. Failure occurs as fretting at the sheetmetal contact edge. To reduce fretting, the grommet is printed with the rib contact surface facing the build platform to avoid a slightly tacky skin on the sealing face.
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    Certification & Compliance
    More Introduction

    3D Systems FabPro™ Elastic BLK Elastomer is a black, UV-curable acrylate photopolymer qualified for the FabPro 1000 DLP vat photopolymerization system. The resin polymerizes at 405 nm and is supplied in pre-packaged cartridges that interface with the printer’s material handling. The material is formulated for functional elastomeric parts requiring repeated flexure, compression, or tensile recovery, rather than rigid structural housings. It is used with the FabPro 1000 build platform measuring 125 mm × 70 mm × 150 mm, with selectable layer thickness settings of 30 µm, 50 µm, and 100 µm. These layer thickness settings influence curing depth, interlayer adhesion, and support contact morphology.

    Material qualification is performed after UV post-cure and conditioning at 23 ± 2 °C and 50 ± 5 % RH. Table 1 lists representative values from the manufacturer’s published datasheet. These values are batch-dependent and are not guaranteed limits. Tensile specimens are printed in the orientation specified by the manufacturer and tested according to ASTM D638-14; orientation-dependent anisotropy is present because the layer interface can act as a crack-initiating plane.

    Representative published datasheet values for FabPro Elastic BLK after UV post-cure
    PropertyValueTest method
    Liquid viscosity at 25 °C300 cPASTM D2196
    Cured density1.10 g/cm³ASTM D792
    Shore A hardness65 AASTM D2240
    Tensile strength at break4.0 MPaASTM D638
    Elongation at break160%ASTM D638
    Tear strength15 kN/mASTM D624
    Compression set, 22 h at 23 °C15%ASTM D395
    Water absorption, 24 h at 23 °C0.9%ASTM D570

    After the recommended post-cure cycle, the nominal Shore A hardness is 65 A. The effective surface hardness can be lower on undersides because of resin-rich layers that are not fully cured before support removal. Under-curing can also reduce density and increase water absorption. Batch acceptance protocols often add a control tensile bar per ASTM D638-14 and a tear specimen per ASTM D624-00(2020) because pigment dispersion and inhibitor concentration can vary between resin lots.

    Rheologically, the liquid resin is formulated with a viscosity low enough for recoat at 25 °C, but it is not a Newtonian fluid at low shear. The FabPro 1000 recoat blade applies shear to the liquid film; if the material has aged or if the vat temperature is below the recommended range, the resin may not level completely before exposure and the layer thickness can vary by several micrometres. In production, recoating variation appears as horizontal banding or as localized delamination in the first 2–5 layers of the build. This failure mode is more common with elastomers than with rigid resins because the green layer’s low modulus cannot resist the peel forces during platform retraction. Operators often reduce print speed and use a longer vat stabilization period between builds when ambient conditions fluctuate.

    When Shore A 65 Elastomer Replaces RTV Silicone in Low-Volume Seal Production

    In fluid-sealing applications, FabPro Elastic BLK is used as a replacement for room-temperature-vulcanizing silicone when production quantity is too low for compression molding and when multi-material insert molding is not available. The primary evaluation metric for a seal is compression set, measured under ASTM D395-18 method B at 23 °C for 22 h. Published representative data place the compression set in the range of 10–20%, depending on post-cure duration and section thickness. This is higher than a post-cured platinum-cured RTV silicone system, but it is adequate for short-run dust seals, access covers, cable grommets, and low-pressure gaskets. The material is not suitable for hot-water or steam seals because the acrylate network loses stiffness above 60 °C and the water-absorption value of 0.9% after 24 h immersion can promote dimensional change.

    Low-pressure seal applications include electrical enclosure gaskets, connector boots, and protective bellows. The material can be used for compression interfaces only when the applied strain is below the compression set limit. For a typical solid gasket with 30% initial compression, the retained sealing force after 22 h at 23 °C can be estimated from compression set data, but stress-relaxation data are not published. For flanges with wide gaps, a hollow or lattice geometry is preferable because it reduces the local compressive strain and keeps the elastomer within the range where recovery is more complete. A honeycomb or lattice core printed with 50 µm layers and 1.0 mm wall thickness has been used for gaskets where a solid cross-section would exceed the material’s compression set at the available preload; however, published data for this specific configuration are limited.

    Vibration-isolation pads and ergonomic grips are additional uses. Damper pads printed in 50 µm layers with a 2–3° draft angle on side walls allow support removal without tearing the low-modulus surface. When printed with a solid or high-dense fill, the material provides a lower durometer contact face than rigid photopolymers, but the part should be tested under the relevant compressive load rate because the stress-strain response is viscoelastic. The manufacturer’s published data do not cover all cyclic load frequencies. For rotating equipment, a fatigue test under the intended amplitude should be performed because tear-initiated edge cracking can occur at strain concentrations. Elastomeric mounts for light-duty equipment can be produced in small batches, but the damping effectiveness is not characterized by a published loss factor. Users must perform dynamic mechanical analysis or a forced-vibration test. Without a full dynamic mechanical thermal analysis curve, applying this material at frequencies above 100 Hz or below 0 °C requires confirmation because the material may stiffen and lose elastomeric recovery.

    What Limits Green-State Handling Before UV Post-Curing?

    Green-state parts immediately after printing retain a liquid uncured monomer film that must be removed before the elastomer reaches handling strength. The primary processing boundary is the time between build completion and solvent cleaning. If parts remain in the printer vat or on the platform for more than 30 min in ambient air above 60% RH, the uncured acrylate surface can absorb moisture, producing a white bloom after cleaning. Dimensional drift before post-cure is observed when supports soften and allow wall movement. The printer maintains a resin temperature setpoint, but the resin tray and recoater require a controlled environment because viscosity rises below 18 °C, increasing recoating force and leading to incomplete layer wetting.

    Washing is performed in two solvent baths. The first bath removes the bulk of the uncured resin; the second bath reduces residual contamination. Typical cleaning solvents are high-purity isopropyl alcohol or the manufacturer’s approved alternative. A first-stage wash of 10–15 min in an ultrasonic unit operating near 40 kHz is used for components with blind holes or undercuts; flat parts may be cleaned in 5–10 min. Aggressive agitation beyond 20 min can produce solvent uptake in the green elastomer, which swells the surface and leaves a tacky film after drying. Parts must be dried with compressed air at a pressure no greater than 2 bar before post-curing.

    Post-curing is performed with a 405 nm flood source. The manufacturer’s processing guide ties the required dose to part thickness; a typical post-cure lasts 60–120 min in a calibrated chamber, with thicker sections requiring the longer duration. Undersized UV chambers that deliver less than the specified irradiance cause a lower degree of acrylate conversion, which depresses Shore A hardness and increases compression set. The effect is not linear: a partially cured sample can exhibit a Shore A drop of 2–5 points and a measurable increase in tack. Therefore, the UV chamber should be checked with a calibrated radiometer at the beginning of each shift. Building nested parts or stacking on translucent trays during post-cure reduces dose uniformity and should be avoided.

    Orientation-specific anisotropy is also relevant. In a horizontally printed tensile bar, tensile strength may be higher than in a vertical tensile bar because the crack path is not aligned with the layer interfaces. The datasheet values are generally obtained from specimens printed flat on the build platform. If vertical walls are unavoidable, the cross-section should be increased or the post-cure should be extended to improve interlayer conversion. Resin lot qualification is critical because pigment dispersion and inhibitor concentration vary. A qualified lot may show a viscosity shift of ±10% from the nominal value and still produce acceptable parts, but a larger shift requires adjustment of the printer material profile. If the printer does not allow manual profile editing in production mode, incoming material should be tested by drawing a small sample through a laboratory viscometer per ASTM D2196 at 25 °C. If the viscosity is above the upper limit, the resin can be warmed gently in a sealed container, but uncontrolled heating above 35 °C can begin thermal initiation.

    Tear Propagation Resistance and Compression Set in Cyclic Flexure

    Tear resistance is evaluated using ASTM D624-00(2020) die C or die T specimens. The reported representative value is 15 kN/m. Tear strength is sensitive to print orientation and post-cure; vertically printed specimens often show lower values because the crack can travel along interlayer planes. For parts with living hinges or bending tabs, a tear test alone is insufficient. The elastomer should be evaluated under repeated flexure using a De Mattia flex setup or similar, because resistance to tear propagation under continuous cycling determines service life. Published datasheet values do not include a full fatigue-life curve; for safety-critical or load-bearing flexible components, internal validation is required.

    Compression set and tensile properties are measured under ASTM D395-18 and ASTM D638-14. The reported elongation at break of 160% is for a fully post-cured specimen. In the green state or after only a short post-cure, elongation may be lower and failure may occur at the layer interface. The low crosslink density required for elastomeric behavior also allows creep under static load. Parts used as bumpers or spacers should be derated because creep displacement is not captured by a single tensile test. When a long-term static load is present, the manufacturer’s data do not provide a creep modulus; testing under the actual service temperature is required.

    Support removal and orientation are critical because the green elastomer tears more easily than rigid photopolymers. Build orientation should be arranged so that support contacts are placed on non-critical surfaces and do not cross thin flexing regions. A draft angle of 2–3° on vertical walls reduces the contact area between support tips and the part; flat undersides printed parallel to the platform increase the number of supports and raise the probability of surface scar damage. The FabPro 1000 DLP projection system has a native pixel pitch of 65 µm, but the effective resolution on a low-modulus elastomer is influenced by resin migration before photopolymerization. Shallow features below 0.5 mm may not reproduce accurately if the uncured resin film thickness on the build surface exceeds the cure depth. The minimum wall thickness for freestanding elastomeric walls is commonly larger than the equivalent rigid-resin wall; walls below 1.0 mm may distort during peeling because the part’s green modulus is too low to resist the separation force.

    Surface finish is affected by layer steps and support removal. If a smooth sealing face is required, the part can be oriented so the critical face is not in contact with supports. Sanding or polishing elastomeric photopolymer is less effective than on rigid resins because abrasive particles can embed and nucleate tears. Chemical smoothing is not recommended for this material; the solvent that softens the surface may also reduce tear strength. Dimensional accuracy after post-cure is typically checked with a calibrated optical comparator or coordinate measuring machine. The manufacturer’s published tolerance is not a fixed linear value because shrinkage varies with geometry, orientation, and degree of cure; printed reference coupons should be measured before accepting a production build. Scale-up from one part to a full build tray can change the thermal history. A densely packed tray increases resin temperature during the build because the photopolymerization exotherm has less time to dissipate. That temperature rise lowers viscosity and may increase cure depth, resulting in overgrowth on undersides. Consequently, a first article from a sparse build cannot be used to qualify a high-density production tray.

    How Does FabPro Elastic BLK Differ from FabPro Tough BLK?

    The principal difference between FabPro Elastic BLK and FabPro Tough BLK is the crosslink density and phase structure. FabPro Tough BLK is a rigid acrylate photopolymer with high tensile strength and low elongation, whereas FabPro Elastic BLK is formulated to produce a Shore A durometer in the elastomeric range. Table 2 compares typical values from published data. The choice is based on whether the part must function as a structural housing or as a compressible seal, grip, or damper. Mixing the two resin families in the same vat is not permitted; carryover from a previous material lot can alter the crosslink density and reduce either the rigidity of Tough BLK or the elongation of Elastic BLK.

    Comparative typical properties: FabPro Elastic BLK versus FabPro Tough BLK
    PropertyFabPro Elastic BLKFabPro Tough BLK
    Shore hardness65 A80 D
    Tensile strength at break4.0 MPa25 MPa
    Elongation at break160%8%
    Primary mechanical responseLow modulus, high elongationRigid, high modulus

    FabPro Elastic BLK is also distinct from casting resins in the FabPro portfolio. Casting resins are designed for burnout with low ash content; Elastic BLK is not designed for investment casting and will leave excessive residue if burned out. Printed elastomer parts should not be used as sacrificial patterns where thermal decomposition above 300 °C is required. The material’s typical service temperature is below 60 °C, which limits its use in engine-compartment or hot-gas applications. Exposure to acetone or methyl ethyl ketone can swell and soften the acrylate network within minutes. Even short contact with strong solvents used for cleaning the work area can create surface tack. If unavoidable, a quick wipe should be followed by drying and inspection; solvent immersion is not recommended.

    Storage is part of the processing window. The resin cartridge should be stored in a dry, dark environment at 15–30 °C and allowed to reach room temperature before shaking or loading. Prolonged storage above 30 °C can accelerate inhibitor depletion and cause premature polymerization in the cartridge or vat. Before each production run, the material should be visually inspected for gel particles or pigment separation; the cartridge may require rolling or agitation according to the manufacturer’s instructions. The uncured resin contains acrylate monomers and photoinitiators. Handling requires nitrile gloves and safety glasses; ventilation should be sufficient to keep vapor exposure below the occupational exposure limits listed in the safety data sheet. The cured elastomer is not rated for food-contact applications under FDA 21 CFR 177.2600 and no compliance statement under EU 10/2011 is published. Chemical compatibility must be verified for the specific service environment; the acrylate network is generally resistant to dilute aqueous solutions but is not recommended for continuous contact with ketones, esters, chlorinated solvents, or strong alkaline cleaners. Amine-containing additives should be avoided because residual amines can react with the uncured acrylate and create a tacky, poorly cured surface.

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