3D Systems VisiJet M2 EBK is a UV-curable elastomeric photopolymer engineered for MultiJet Printing on the ProJet MJP 2500 and ProJet MJP 2500 Plus additive manufacturing platforms. The uncured material is a black, low-viscosity liquid formulated for piezoelectric drop-on-demand jetting; layer thickness is typically 32 µm. After UV irradiation, the acrylate-functional oligomer network crosslinks into a rubbery solid with an opaque black cross-section. Manufacturer-published typical properties include a Shore A hardness of 30 per ASTM D2240, tensile strength of 1.0 MPa and elongation at break of 250 % per ASTM D412, and tear strength of 4.6 kN/m per ASTM D624. Solid density is approximately 1.0 g/cm³ per ASTM D792. The product is intended for functional elastomeric prototypes, short-run seals, gaskets, paint-masking fixtures, grips, vibration isolators, and connector boots. Unlike fused filament or laser-sintered flexible materials, M2 EBK builds with smooth sidewalls and supports fine internal channels through a sacrificial wax support system. The printed material is not a thermoplastic elastomer; after cure it does not melt and cannot be reprocessed thermally.

What limits the use of VisiJet M2 EBK in continuous-service sealing applications?

Continuous sealing performance is controlled by compression set, stress relaxation, and fluid resistance rather than tensile elongation alone. For VisiJet M2 EBK, published compression-set data under ASTM D395 Method B are limited; sealing qualification should therefore measure compression set at the actual service temperature, installed compression ratio, and recovery time. The material is best applied in static seals with peak compressive strain below 15 %. Higher compression ratios may accelerate stress relaxation and cause loss of sealing contact pressure after thermal cycling. Prolonged contact with polar solvents such as ketones, esters, and chlorinated hydrocarbons can soften the crosslinked network; hardness, mass change, and volume swell should be evaluated by ISO 1817 and ASTM D471. Non-polar hydrocarbon exposure may be less aggressive, but fuel and oil sealing should not be assumed without immersion testing. Service above 50 °C may increase compression set and reduce tear resistance, so applications above this threshold require continuous-load relaxation testing. Because the network is UV-crosslinked, extended outdoor exposure can increase crosslink density and reduce elongation at break.

Layer-wise UV cure introduces anisotropic mechanical response that is not reflected in bulk datasheet values generated from printed panels. Z-axis tensile elongation and tear strength can be lower than in-plane values because interlayer crosslink density is affected by oxygen inhibition, UV attenuation, and the time interval between successive layers. The magnitude of this reduction depends on build orientation, layer thickness, and post-cure; published data for this specific configuration is limited. When designing sealing ribs or flexural snap features, the flexing axis should be oriented in the XY plane, and sharp corners perpendicular to the Z-axis should be avoided. Thin ribs below 0.5 mm can tear during support removal or exhibit lower tear resistance. Corners with radii smaller than 0.5 mm can act as tear initiation sites under repeated extension. For dynamic flexing, strain per cycle should remain below 5 % if service life exceeds 10,000 cycles, and validation should follow ASTM D430 or an equivalent flex fatigue method. Batch-to-batch variation on production machines is controlled by sealed cartridge storage, resin recirculation before jetting, and maintenance of printhead temperature within the manufacturer’s specified range.

When a Shore A 30 photopolymer replaces cast urethane gaskets

Cast urethane gaskets usually provide higher tear strength and lower piece cost at volume, but they require mold tooling and lead times measured in weeks. M2 EBK becomes a practical replacement when part quantities are below 100 units, when sealing geometry changes frequently, or when internal channels and undercuts cannot be molded in a single operation. The trade-off is lower tear strength and anisotropic elongation in the Z-axis. Cast urethane with Shore A 30–40 hardness may exhibit tear strength two to three times higher than the printed material, so load-bearing gaskets should be redesigned with thicker sidewalls and a compression stop. For vacuum workholding masks, leak tightness must be validated because microvoids and incomplete interlayer cure can create leakage paths. Compressibility and recovery should be measured per ASTM F36, and tear resistance per ASTM D624 before replacing a cast or die-cut part. In masking applications for plasma treatment or painting, the black color of EBK provides light blocking and simplifies visual inspection, but the user must confirm that no low-molecular-weight material migrates to the substrate. Surface energy testing per ASTM D2578 or extractables testing may be required for clean-release applications.

Compared with rigid ProJet MJP materials such as VisiJet M2R-CL, the EBK grade provides high elongation at the expense of modulus and creep resistance. It differs from the natural elastomeric grade in pigment loading and appearance; opacity and color stability should not be assumed to transfer from natural to black versions without reprinting a test coupon. The material cannot be directly compared with laser-sintered TPU powders because the UV-cured network is thermoset and does not exhibit a true melting transition. This difference becomes important when parts are exposed to high-humidity environments or detergent washing; swelling and hydrolysis resistance should be tested per ISO 62 and ISO 175. For electronic enclosures, cured parts may evolve volatile condensable species; if used inside sealed optical or electronic modules, outgassing should be evaluated per ASTM E595.

Post-processing and support-removal constraints on the ProJet MJP 2500

On the ProJet MJP 2500, the build chamber measures 294 mm × 192 mm × 150 mm, and parts are surrounded by sacrificial wax support material that must be removed after printing. Support removal is performed in a heated bath or oven; exceeding the recommended temperature or leaving thin elastomeric sections in the bath too long can produce surface tack, deformation, and loss of fine sealing ribs. Production failure modes observed on manufacturing lines include tearing of thin overhangs during manual wax removal, wax residue in blind holes, and softening of unsupported walls when bath temperature exceeds the material’s dimensional stability threshold. After support removal, parts may be rinsed with isopropyl alcohol or a manufacturer-approved solvent. Excessive solvent contact can extract low-molecular-weight species and increase surface hardness; immersion should be limited to 5 min unless validated for the specific geometry. Post-cure requirements should follow the manufacturer’s current processing bulletin; published data for additional thermal post-cure effects on EBK are limited. Dimensional inspection should follow ISO 291 conditioning at 23 °C and 50 % RH for 24 h before measurement. Batch-to-batch differences in support wax formulation can influence adhesion to the elastomer; first-article trials should include a tear-out test of blind holes and thin ribs.

When compliance and storage boundaries control material selection

Uncured resin may be classified as skin sensitizer under EC 1272/2008; handling should use nitrile gloves, chemical safety goggles, and local exhaust ventilation. Cartridges should be stored at 15–25 °C in sealed, light-excluding containers and used within the manufacturer’s stated shelf life, commonly 12 months from date of manufacture. Opened cartridges should be consumed within 30 days to prevent viscosity drift and pigment settling. Cured parts are not classified as hazardous, but grinding or machining can generate particulate that should be captured by local exhaust. The product is not intended for direct food contact or long-term implantation; no FDA clearance is implied. Compliance with 2011/65/EU RoHS Recast and REACH candidate list obligations should be confirmed from the supplier’s current material compliance documentation. The following control points are commonly requested for qualification:

On multi-machine production lines, the largest source of property drift is not the printer itself but the storage condition of partially used cartridges. Resin exposed to office lighting and humid air can absorb moisture, raising viscosity and changing jetting drop mass. Printhead temperature compensation cannot fully correct for viscosity above the specified range; the result is missing jets and non-uniform layer thickness at the edges of the build envelope. Production control plans should therefore log cartridge opening date, storage temperature, and relative humidity. If ambient relative humidity exceeds 60 %, pre-condition cartridges in a dry cabinet before use and minimize open time. The material should not be combined with amine-based additives or coatings because amine species can react with residual acrylate groups and accelerate surface crosslinking or tack. For parts that require painting or adhesive bonding, surface preparation should be validated by ASTM D3359 cross-cut adhesion or ISO 2409. The operational boundary for sustained mechanical loading is conservative; service life is best confirmed by functional testing on the actual assembly rather than by extrapolation from tensile data alone.