The Rigur rubber-like PolyJet combination is configured with TangoGray FLX950 as the primary jetting resin and TangoBlack FLX973 as the secondary stiffness modifier. The two resins are jetted from independent heads and UV-cured in the same pass. Layer thickness is selectable at 16 µm or 30 µm depending on the PolyJet platform. Digital blend ratios are assigned volumetrically in PolyJet Studio. Because TangoGray FLX950 is rated in the 40–45 Shore A range and TangoBlack FLX973 is rated in the 61–65 Shore A range under ASTM D2240, the blend space covers compliance-sensitive prototype functions. Specimens are conditioned at 23±2 °C and 50±10 % RH for 24 h before tensile or hardness measurement. The following applications treat the digital blend not as a direct replacement for injection-molded TPE, but as a short-run fixture, seal, ergonomic, and training medium with boundary conditions defined by photopolymer chemistry.

How Does a 75:25 Blend Alter Insertion Force and Tear Propagation in Automotive Grommet Prototypes?

In automotive wiring harness development, rubber-like PolyJet parts are used for firewall grommets, b-post boots, and connector elbow seals. A starting volumetric ratio of 75% TangoGray FLX950 to 25% TangoBlack FLX973 is selected for harness grommets because it raises tear resistance relative to the primary-only condition while preserving insertion collapse. The lower elongation of TangoBlack FLX973, approximately 47–63% versus 70–100% for TangoGray FLX950 under ASTM D412, reduces over-extension of thin sealing lips during assembly. Tear behaviour is measured on die-type specimens according to ASTM D624 after the same 24 h conditioning used for hardness testing.

Build orientation is the dominant process variable for seal prototypes. Grommet lips placed on the downfacing side exhibit higher surface roughness after support removal. Support material SUP705 or SUP706 is removed with a water-jet station; residual support in grooves below 1.0 mm can increase insertion force and produce nonuniform lip deflection. For radial seals, the lip plane is oriented upward or vertical to preserve the smooth surface. Final assembly force is measured using a universal tester, but OEM pass-fail values are drawing-specific because no unified SAE standard covers printed elastomer grommets. Long-term underhood heat exposure is outside the intended use of these materials for production sealing; the parts are used for fit, retention, and routing verification rather than validated thermal service.

For medical training phantoms, vessel contrast and tactile variation are produced from a primary TangoGray FLX950 matrix, while a secondary-rich blend of 20:80 TangoGray FLX950 to TangoBlack FLX973 is used for vessel walls, ligament bands, or bronchial stiffening elements. The digital combination enables a single continuous phantom to contain soft parenchyma-like regions and firmer conduit boundaries without adhesive assembly. This is relevant for central venous cannulation trainers, liver biopsy models, and orthopedic ligament tension simulators. Compliance is limited to external intact-skin use. The neat resins and the digital combination are not validated for implantation, mucosal contact exceeding 24 h, or USP Class VI certification in this configuration. A cytotoxicity evaluation under ISO 10993-5 and sensitization evaluation under ISO 10993-10 must be performed by the end user when the printed simulator will contact multiple trainees or reside in a clinical skills laboratory.

Process parameters for medical phantoms favour matte finish to reduce surface gloss and improve visibility of anatomical landmarks. Multi-material transitions at a voxel level create gradients; interface delamination can occur if the part is flexed repeatedly after water-jet cleaning. A transition band of 2.0 mm between hardness zones reduces cohesive failure. The operator should confirm transition integrity on printed test slabs before full phantom assembly. Moisture uptake and dimensional drift are managed by conditioning printed phantoms at 23±2 °C and 50±10 % RH for 24 h before dimensional inspection.

Evaluating Compression Set and Surface Tack in Consumer Wearable Seal Prototypes

Because compression recovery and skin-contact softness are primary requirements, consumer wearable prototypes are built from a digital blend of 70% TangoGray FLX950 and 30% TangoBlack FLX973. This ratio is used for earbud cushion prototypes, smartwatch band flex zones, and VR gasket contours. Compression set is evaluated under ASTM D395 Method B at 23 °C for 22 h at 25% strain. The test reports permanent set as a percentage of applied deflection. Higher TangoBlack content reduces permanent set at room temperature, but at the cost of lower ultimate elongation. Parts that must fold, twist, or undergo snap-fit assembly are tested for crack initiation after 10 manual cycles at the intended flex angle. This in-house screening is comparative because no ISO method specifically addresses fatigue of PolyJet digital blends.

Surface tack remains a critical limitation after support removal. Water-jet cleaning alone does not remove the thin partially cured boundary layer on downfacing surfaces. For wearable prototypes, post-processing includes broad-spectrum UV post-exposure or a thin acrylic-based clear coat, but any coating alters tactile hardness and elongation. The uncoated surface of TangoGray FLX950 can exhibit higher tack than TangoBlack FLX973; this difference is amplified above 30 °C. Accelerated ageing under ISO 188 at 70 °C for 168 h is used only as a screening test, not as a service-life prediction, because photopolymer oxidation behaviour differs from thermoplastic elastomer oxidation.

In soft robotic gripper development, pneumatic actuator bladders are printed with a digital blend of 65% TangoGray FLX950 and 35% TangoBlack FLX973. The primary resin provides the low-strain extensibility needed for balloon-like inflation, while the secondary resin increases interlayer tear resistance at the bonded interface. Wall thickness is maintained at or above 1.5 mm. Thinner walls show measurable leakage at the Z-direction layer boundaries when pressurized, even after support removal. Manometric leak testing at 20 kPa for 30 s is used as a screening procedure for each actuator. Published burst-pressure data for this specific printed bladder configuration is limited. Final pressure boundaries must be determined on the exact geometry because internal ribs, radius transitions, and drain holes create local stress concentrations that are not captured by coupon tensile data.

The actuator cavity is designed with a sacrificial support path that can be flushed completely. Trapped support material inside a pneumatic chamber becomes a compliance defect and a source of intermittent valve clogging. Water-jet flushing is followed by 24 h drying at 40 °C in a forced-air oven before first inflation. The drying step reduces absorbed water that would otherwise plasticize the polymer and lower the effective Shore A reading. Because the Tango materials are acrylate-based photopolymers, direct contact with ester- or ketone-containing pneumatic lubricants is avoided; such fluids can swell the bladder and alter the inflation response.

When End-of-Arm Tooling Requires Coefficient of Friction and Shore A Matching Across Contact Pads

On automated assembly lines, non-marring contact pads, locating pins, and pick-and-place fingers are printed from the Rigur rubber-like combination. A volumetric ratio of 80% TangoGray FLX950 to 20% TangoBlack FLX973 is used for pads that must grip painted or anodized surfaces without scratching. Static coefficient of friction is measured against a 304 stainless steel counterface using ASTM D1894. The test is run at 150 mm/min after the same standard conditioning. Measured static friction is not an intrinsic property; it varies with surface finish and pressure. Therefore the build is specified in matte mode, not gloss mode, because the matte finish produces less variation across the pad face.

Pad hardness must be matched to the application. Hardness is mapped across the printed pad face by taking duplicate ASTM D2240 readings at 12.5 mm from the edge and at the center. Shore A values on the downfacing side may read 2–4 points lower than the top surface if support residue remains. A hard secondary-rich layer of 50:50 TangoGray FLX950 to TangoBlack FLX973 is used in the mounting boss region to resist compression set under clamp force. The limitation is exposure to cutting oil and polar solvents; ester- or ketone-containing cleaning agents cause swelling and reduce pad service life. Documented failure modes include edge delamination when pad thickness drops below 2.0 mm and clamp force is applied repeatedly at an angle.

Across footwear midsole and orthotic prototypes, gradient hardness zones are produced in a single continuous build. TangoGray FLX950-only zones are placed under the heel and forefoot for softness, while a 50:50 blend with TangoBlack FLX973 is used under the arch and metatarsal rim for support. The digital transition is set over a 5.0 mm band to avoid an abrupt flex hinge. Compression-set behaviour follows ASTM D395 Method B at 23 °C for 22 h; heat-aged compression set under ISO 815-1 at 70 °C is used only for comparative screening because the material is outside its intended continuous service window. Energy return is not validated under ASTM F1614 for these resins. Published data for the hysteresis and dynamic energy loss of this TangoGray/TangoBlack blend in midsole geometries is limited. The printed parts are used for fit trials, last comparison, and wear-test fixtures rather than functional midsole production.

Printing at 30 µm layer thickness reduces build time but produces more visible layering on the sidewall. For orthotic shell verification, the insole is oriented with the foot-contact surface upward to keep the smoothest face on the loaded side. Support material is removed within 1 h of build completion to minimize surface varnishing on high-curvature arch regions. Conditioned dimensional inspection before fit testing prevents errors from moisture-induced expansion.

Dynamic Flex Durability of 85:15 Rubber-Like Elements in Overmold Simulation and Living-Hinge Mock-Ups

For enclosure prototypes that combine rigid frames with rubber-like gaskets, TangoGray FLX950 is used as the primary volume and an 85:15 TangoBlack FLX973 blend is used for isolated flexure elements. This is applied to battery door latching simulations, medical device housing seals, and automotive interior trim clips. Flexural durability is screened by 10 000 cycles at 1 Hz on a benchtop cycling fixture with a fixed angular displacement. Cycle count and angular displacement are not defined by a single ISO or ASTM method for photopolymer digital blends; the test is therefore a comparative in-house screening method, not a certified fatigue test. Failure initiation is monitored visually and with 20× microscopy for cracks at the blend boundary and at support-scarred surfaces.

Overmold simulation accuracy is limited by the isotropic nature of the PolyJet rubber-like blend. Injection-molded TPE overmold interfaces develop a chemical or thermal bond that depends on the rigid substrate temperature. The printed model cannot replicate that interfacial adhesion. The blend is therefore used to validate geometry, fit, and assembly force, not peel strength. Peel adhesion under ASTM D429 is not applied unless the printed part is bonded to a rigid substrate in a secondary operation. The absence of a validated peel adhesion test for as-printed multi-material interfaces is an operational boundary that must be documented in any test request or supplier drawing.