Proto3000 Objet Digital Materials™ DM_9870/9770 Rubber-like Prototyping Polymer is a jetted photopolymer elastomer supplied for Objet Connex and Objet Eden PolyJet platforms equipped with multi-material mixing capability. The material is not a pre-compounded thermoplastic; the printer forms the DM_9870/9770 digital-material recipe by co-jetting two base acrylate photopolymers at voxel-level ratios, followed by immediate UV cure during the print pass. The 9770-series hardness designation aligns with a nominal 70 Shore A durometer level when measured on a conditioned specimen according to ASTM D2240-15 or ISO 7619-1:2010. Build resolution on Connex-class systems is selectable between 16 µm and 30 µm layer thickness with an X/Y addressability of 600 dpi. The material is therefore positioned between the softer Agilus30/TangoPlus-type PolyJet elastomers and rigid digital ABS grades, and it is intended for functional prototypes requiring elastic recovery after flexing, Shore A consistency across a build tray, and the elimination of cast-silicone tooling.

Which Property Windows Control Selection of DM_9870/9770 for Functional Prototypes?

Mechanical property data for the Shore A 70 digital-material class are typically generated on Type IV dogbones or ISO 37 dumbbells after 48 h conditioning at 23 °C and 50% RH per ASTM D618-21. Because PolyJet rubber-like parts are build-orientation-dependent, Z-oriented specimens commonly show lower tensile strength and elongation than XY-oriented specimens; designers should not apply XY tensile data to interlayer separation loads. Representative performance-class values are listed below; exact lot-specific values must be confirmed against the current Proto3000/Stratasys datasheet for the DM_9870/9770 recipe, because digital-material blend ratios, print mode, and cleaning history shift the as-printed stress-strain response.

For sealing and gasketing geometries, the limiting design property is rarely tensile strength; compression set and stress relaxation under constant displacement determine whether a flange seal retains contact pressure after thermal soak. Compression set for Shore A 70 PolyJet materials is measured under 25% compressive deflection for 22 h at constant temperature using ASTM D395-18 method B or ISO 815-1:2014. Published data for the exact DM_9870/9770 formulation is limited; however, Shore A 70 PolyJet rubber-like materials generally show higher compression set than addition-cure RTV silicone and lower compression set than many plasticized PVC elastomers, which restricts the grade to short-to-medium duration sealing evaluations rather than permanent production seals. In a bench-test environment, a 2.0 mm thick gasket compressed to 1.6 mm may retain adequate reaction force for an ambient-temperature weekend test but should not be treated as a multi-week closure system without stress-relaxation data.

The stress-strain behavior of DM_9870/9770 is nonlinear even below 20% strain; linear elastic finite-element assumptions are not valid for load-bearing seals. Modulus values derived from the initial tangent slope are not directly comparable to Shore A 70 injection-molded TPU, because photopolymer elastomers often show higher small-strain modulus but earlier yielding at an interlayer. When a design is translated from a TPU datasheet, the correct value to compare is the secant modulus at the service strain, not the published ultimate elongation. This is particularly important at the interface of rigid and rubber-like digital materials, where a mismatch in shrinkage and modulus creates a stress concentration that can exceed the interlaminar strength of the elastomer layer.

Hardness testing on thin DM_9870/9770 sections requires a rigid substrate or a stacked specimen; ASTM D2240-15 specifies a minimum thickness of 6.0 mm unless calibration is performed with a similar stack. For a printed part with wall thickness below 6.0 mm, direct durometer readings are inflated by the rigid backing plate and should not be compared to datasheet values. In a production-floor check on a 2.0 mm gasket, a Shore A measurement over a rigid steel plate is a composite number, not a material property.

Support Removal and Solvent Compatibility Boundaries

Because DM_9870/9770 is printed with a sacrificial support gel, support removal is a process boundary rather than a cosmetic step. The uncured support is a low-molecular-weight photopolymer that is normally removed with a water-jetting station operating at the equipment manufacturer’s prescribed pressure, typically in the range of 2–5 MPa on dedicated Objet water-jet cabinets. For blind internal channels smaller than 2 mm in diameter, water-jetting alone is frequently insufficient; a short immersion in a supported alkaline cleaning bath followed by thorough neutralization is required. Excess residence time in aggressive alkaline or solvent-based cleaners, however, swells the acrylate network and can shift a 70 Shore A surface to a visibly softer, tacky condition. Production-line observations on Objet parts with trapped support gel show that residual gel left in blind cavities can polymerize during post-cure or service illumination and create brittle inclusions at flexural hinges.

The water-jetting process is not dimensionally neutral. Thin walls under 1.5 mm can deflect under the cleaning jet; for a convoluted gasket section with ribs of 1.0 mm, the operator should reduce pressure and increase standoff distance rather than relying on a single high-pressure pass. Residual moisture after cleaning is trapped in blind pockets; if the part is immediately placed in a heated build oven or painted, trapped water vapor can create microvoids at the interface between the rigid base and the elastomer. For overmolded-like assemblies, a forced-air drying step at 40–50 °C for 2–4 h is advisable before adhesive bonding or painting.

Solvent contact after cleaning must be controlled. Prolonged immersion in isopropyl alcohol, acetone, or ester-based solvents is not recommended; these solvents extract low-molecular-weight acrylate fractions and cause dimensional drift. If a cleaning solvent is required for bonding preparation, a flash wipe with 70% isopropanol followed by forced-air drying at 40–50 °C for 15–30 min is used on some process lines, but published compatibility data for DM_9870/9770 remains limited. The cured material should be protected from continuous UV exposure as the acrylate network continues crosslinking and may embrittle over time.

Batch-to-batch variance in jetting viscosity is controlled by the printer’s onboard heating and cartridge identification, but systems with worn wiper assemblies can show unstable droplet formation. When droplet formation becomes unstable, the resulting part surface may exhibit a distinct orange-peel pattern and local Shore A hardness can vary by 3–5 points. Maintenance of the printhead array, particularly the roller and waste-wipe assembly, is therefore critical when running DM_9870/9770 for Shore A-critical prototypes.

The DM_9870/9770 differs from fused filament fabrication thermoplastic polyurethane in that it is a thermoset; it cannot be melt-reprocessed after printing, and its interlayer bonds are formed by photopolymerization rather than thermal fusion. Compared with room-temperature vulcanization silicones, the digital material builds directly into the final elastomer without mold tooling, but it exhibits higher compression set and lower elongation at break. Compared with softer PolyJet rubber grades such as TangoPlus or Agilus30, the Shore A 70 class provides greater resistance to point-load indentation and better dimensional stability under self-weight but less low-temperature flexibility and lower tear propagation resistance than the softer grades. In multi-material assemblies, DM_9870/9770 can be combined with rigid PolyJet photopolymers in a single build to produce overmolded-like grips and gaskets; however, the interface between digital materials must be designed as a transition zone rather than a sharp bond line, because shrinkage differences can generate stress concentrations at the junction.

Compared with cast polyurethane elastomers, DM_9870/9770 avoids mold fabrication, but its layerwise build introduces anisotropic tear paths. Tear strength measured in the XY plane is generally higher than in the Z plane; a gasket lip loaded perpendicular to layer lines may propagate a tear at a lower energy than a homogeneous cast part of the same Shore A. Testing should therefore be conducted on specimens cut from the same build orientation as the production prototype, using ASTM D624-00(2012) die C or ISO 34-1:2015 trouser tear methods.

If DM_9870/9770 Is Used to Replace Overmolded TPE in a Proof-of-Concept Build

When simulating a two-shot overmold, the typical TPE wall stock and draft angles used in injection-molded production parts require revision. A soft TPE overmold with a 0.8 mm wall can be filled in a steel tool; the same thickness in DM_9870/9770 is prone to buckling during support removal and to layer-interface splitting if the part is flexed repeatedly. For handling-safe geometries on a Connex platform, minimum unsupported wall stock should be held above 1.5 mm and preferably 2.0 mm for seal bosses that experience assembly loads. Sharp corner transitions at gasket roots should be replaced with a minimum fillet radius of 0.5 mm, because notch-sensitive tear initiation occurs earlier in Shore A 70 photopolymer elastomers than in molded TPU.

Draft and clearance tolerances also shift. Injection-molded TPE tolerances of ±0.05 mm across a seal are not typically reproducible on a PolyJet digital-material part in the Z axis; a more defensible design limit for DM_9870/9770 is ±0.15 mm for features under 50 mm and ±0.3% of nominal length above that, depending on print mode and orientation. These limits are not drawn from a specific published ISO dimensional standard but reflect production-floor capability observed on Stratasys Connex-family machines. Published data for this specific configuration is limited; first-article measurement is required for any fit-critical seal.

Storage and handling conditions for the liquid cartridges should follow the Objet materials handling protocol: sealed cartridges are stored at 15–27 °C, protected from UV and moisture, and rotated to avoid settling. The cured DM_9870/9770 parts should be allowed to rest for 24–48 h after cleaning before shore hardness and tensile measurements are taken, because the as-cleaned surface retains residual solvent and is softer than the interior. Post-curing with UV flood lamps is not typically required for the Shore A 70 digital-material class but can shift surface hardness upward by a few points; any post-cure process must be validated on a first-article basis because overexposure accelerates embrittlement and yellows translucent or light-colored build regions.

In connectors and vibration-isolation mounts, DM_9870/9770 is selected for its ability to produce thin elastomeric membranes without tooling. However, the material’s Shore A 70 stiffness means that isolating mounts require lower deflection than a Shore A 30 Agilus30 design; designers should verify the dynamic modulus rather than assuming elastomer-like energy absorption. Dynamic mechanical analysis for this exact formulation is not openly published; first-article testing should include frequency sweeps from 1 Hz to 50 Hz at 23 °C and 40 °C to capture the glass-rubber transition behavior of the acrylate network.

Chemical exposure tests for automotive and consumer applications should include reference fluids rather than simple immersion. For engine-bay sealing probes, a 72 h immersion in ASTM D471-16 reference oil IRM 903 at 23 °C can provide comparative volume swell data; for consumer products, a 48 h skin-oil and sunscreen exposure test is often more predictive of field failure. Exact resistance data for DM_9870/9770 should be requested from Proto3000; generic Shore A 70 acrylate elastomers are not inherently resistant to ketones, aromatic hydrocarbons, or concentrated glycol ethers.

RoHS and REACH status for the exact DM_9870/9770 formulation should be verified by lot-specific material declaration from Proto3000; the presence of trade-secret acrylate monomers may require review under extended producer responsibility schemes. The cured part is not considered a food-contact material under FDA 21 CFR 177.2600 unless a specific written compliance statement is supplied for the build lot. No statement in this document replaces the safety data sheet or the Objet materials handling guide for uncured photopolymer exposure.