Automotive Soft-Touch Interfaces Demand Shore A 50–70 Digital Rubber Overmoulds

TangoBlack FLX973 is combined with VeroBlackPlus RGD875 to produce low-gloss rubber-like control elements, overmoulded switch interfaces, and interior trim prototypes. The volumetric ratio is not an operator-set weight percentage; the PolyJet build software proportions the primary flexible resin and the secondary rigid resin to deliver a target Shore A 50–70 range. VeroBlackPlus RGD875 raises tensile modulus and reduces surface tack relative to unmodified TangoBlack FLX973, but it also lowers elongation at break and increases brittleness at sharp geometry transitions. For an automotive HVAC knob or mirror switch bezel, the grip surface is oriented in the XY plane and built at 16 μm layer thickness because Z-axis stacking produces measurable durometer anisotropy. Hardness is measured on both XY and Z faces according to ASTM D2240-15 and recorded separately, not averaged. Support removal from undercut detent features is performed with a low-pressure water-jet fitted with a pencil-tip nozzle; high-pressure cleaning tears the thin elastomer skin at the rigid-shell interface. The terminal components are short-run prototypes or bridge-production parts, not production EPDM or TPV substitutes. Compliance is limited to the REACH and RoHS 2011/65/EU (EU) 2015/863 data supplied in the safety datasheet; no FMVSS 302 flame-spread rating or automotive interior weathering certification is claimed. Prolonged service above ambient temperature requires end-user validation because acrylic-based PolyJet elastomers exhibit creep under sustained compressive load.

In handheld consumer electronics grip overmoulds and wearable strap hinges, a lower Shore A 30–50 target is used, corresponding to a higher volumetric fraction of TangoBlack FLX973 relative to VeroWhitePlus RGD835 or RGD720. The blend is jetted at 16 μm layer thickness when overmould wall thickness is below 1.5 mm; 30 μm high-speed mode is reserved for thick elastomer volumes where compliance dominates and surface smoothness is not the limiting acceptance factor. Because uncured support material is removed from blind recesses through access slots, support-removal tool access must be designed into the print; residual support under internal ribs is a known source of dimensional error and flexural inconsistency. The cured overmould is checked against ASTM D412-16 for tensile and elongation and ASTM D624-00(2020) for trouser tear; acceptance thresholds are taken from the production TPE overmould datasheet, not from generic rubber-like material values. The digital material has no ISO 10993-1 biocompatibility listing and is not certified for prolonged skin contact under the EU Medical Device Regulation; use is limited to mechanical fit and grip evaluation, or the part is coated with a validated skin-contact barrier. RGD720 provides translucent rigid regions where light transmission is needed in wearable prototypes, such as LED windows or optical alignment features. Terminal applications include test-series remote-control side grips, earbud charging-case gaskets, and wrist-worn device strap flexure prototypes. In such parts, the rigid VeroWhitePlus RGD835 or RGD720 phase stiffens mounting bosses while the TangoBlack-rich matrix retains flexibility at living-hinge sections, producing a functional multi-material assembly without insert moulding.

When High-Elongation Digital Materials Replace Silicone in Robotic End Effectors

When rubber-like PolyJet digital materials are evaluated as replacements for cast silicone pads in robotic end effectors, the target Shore A 40–60 blend is selected for workpiece surface compliance. TangoBlack FLX973 provides the low-durometer base; VeroBlue RGD840 or VeroBlackPlus RGD875 is added in a printer-controlled ratio that lowers elongation and increases tear resistance. For palletizing and pick-and-place grippers, the printed suction-cup bellows is oriented with the sealing lip upward to allow drainage of support material from the concave cavity. The sealing lip is built at 16 μm layer thickness; the bellows body can be built at 30 μm to reduce build time. Compression set is evaluated per ASTM D395-18 Method B after 22 h at 23 °C, and the test specimen is printed in the same orientation as the production cup because anisotropic cure depth alters recovery behaviour. In field trials, acrylic-based PolyJet gripper pads show higher creep under sustained vacuum-clamping contact than silicone; replacement intervals must be determined by end-user validation. Published data for this specific TangoBlack FLX973 and VeroBlue RGD840 configuration is limited, so long-term cycle-life validation is performed on the actual workpiece geometry. The terminal parts are robot gripper pads, vacuum cup bellows, and soft jaw inserts for assembly lines. The material is not specified for continuous load-bearing elastomer service; end-user validation under Machinery Directive contact-force requirements is required before deployment.

How Should Shore A 60–70 Elastomer Prototypes Be Built for Medical Simulators?

Medical training models manufactured from TangoBlack FLX973 and VeroBlue RGD840 or RGD720 require a Shore A 60–70 target for vascular walls, organ capsules, and simulated fibrotic tissue. The ratio is not reported as weight percent; the PolyJet system software proportions droplets of the primary and secondary resins to obtain the requested durometer. The part is printed at 16 μm layer thickness in high-quality mode because lumen diameters below 3.0 mm suffer stair-step-induced flow restriction if built at 30 μm. Data generated from CT or MRI segmentation is imported as a multi-material shell; the outer capsule is assigned a higher VeroWhitePlus RGD835 fraction to simulate capsular rigidity, while the inner parenchyma is assigned a higher TangoBlack FLX973 fraction. Support material is removed from tortuous airways or vascular trees using sequential low-pressure water-jet pulses, followed by 24 h drying at 23 °C and 50 % relative humidity before mechanical characterisation. Because the material combination lacks ISO 10993-1 certification and cannot be sterilised by autoclave without softening, the terminal components are restricted to bench-top surgical simulators, anatomical demonstration models, and ultrasound training phantoms. ASTM D638-14 data for rigid-rich regions and ASTM D412-16 data for elastomer-rich regions are generated on flat witness coupons built in the same job; the two data sets are reported separately rather than averaged.

For low-pressure flanged gaskets and elastomer test-fixture seals, a Shore A 60–80 blend is selected, biased toward VeroWhitePlus RGD835 or VeroBlackPlus RGD875 to reduce compression set and improve bolt-flange load distribution. The printed gasket has a sealing bead of 0.5 mm height and 1.5 mm width on at least one face; this bead is oriented upward in the build to avoid stair-step leakage. A 16 μm layer thickness is selected for the bead plane, while the body may use 30 μm where flange face flatness tolerances exceed 0.25 mm. The gasket is conditioned at 23 ± 2 °C and 50 ± 5 % relative humidity per ISO 291 before compression testing. Compression set is measured according to ISO 815-1:2019 on specimen disks printed in the gasket orientation. The material is not specified for continuous immersion in hydrocarbon oils, brake fluid, or polar solvents; resistance testing in the actual process fluid is required because acrylate-based PolyJet elastomers can swell and lose sealing force. Terminal products include test-rig housing seals, lab water-circuit gaskets, and short-run masking plugs. Pressure ratings are not published for this material; low-pressure air or water service requires end-user leak and burst validation before deployment.

Evaluating Elastomeric Vibration Dampers and Masking Tools for Low-Pressure Paint Operations

Paint-shop masking caps, rack contact pads, and vibration isolators are built from Shore A 50–70 TangoBlack FLX973/VeroWhitePlus RGD835 combinations because the rigid phase allows the mask to retain its shape during oven cycling. The parts are printed in high-speed 30 μm mode for larger caps and hangers; only the sealing lip is printed at 16 μm to reduce stair-step paint ingress. Holes and pilot bores are oriented vertically to drain support; features below 1.0 mm are avoided because water-jet cleaning cannot reliably clear blind cavities. The terminal mask must withstand the production paint cure cycle, including solvent exposure and thermal load; if the cure temperature exceeds the supplier-recommended maximum for the digital material, the part can soften and lose dimensional stability, so the user must validate the thermal cycle against the actual oven profile. Compliance testing is limited to RoHS 2011/65/EU (EU) 2015/863 and REACH SVHC screening; no automotive paint-shop specification or OEM paint-line approval is implied. Terminal applications include masking plugs, plug buttons, rack contact pads, and damping collars for low-vibration paint-transfer lines. Solvent-borne paint carriers may swell the TangoBlack-rich phase; a production-paint immersion test is mandatory before masking lots are released.