Automotive fluid-sealing applications for the RBK-ENT-A80 composite are driven by the need to evaluate rigid retainer geometry and elastomeric bulb compression in a single build before committing to EPDM or ACM injection tools. The rigid black VisiJet CR-BK regions form the flange and retention features, while the A80 composite provides the seal lip that is compressed against a test stand surface. Mechanical evaluation follows ASTM D2240-15(2021) for nominal Shore A 80 hardness, ASTM D412-16(2021) for tensile strength and elongation at break, and ASTM D395-18 Method B for compression set after 22 h at 70 °C. The exact CR-BK-to-CE-NT volume fraction in the A80 digital material profile is supplier-proprietary and is published only as a machine-readable build parameter; the composite is not a bench-top liquid blend because the final network structure depends on the spatially resolved jetting sequence rather than bulk mixing. On the ProJet MJP 5500X, the part is built with support material inside hollow sealing bulbs and under the rigid flange, followed by support removal in the supplier-specified heated oil bath and detergent rinse. Dimensional stabilization is performed at 23 ± 2 °C and 50 ± 5 % RH for 40 h before durometer control. Thin elastomeric lips below 1.5 mm must be built in at least three orientations because durometer values are sensitive to boundary-layer cure; published data for this specific thin-wall configuration is limited. Terminal parts include coolant expansion tank cap seal prototypes, oil filter housing O-ring groove validation fixtures, and engine bulkhead wiring grommet prototypes.

In a wearable electronics prototype, the rigid black CR-BK regions supply the snap-fit frame and the A80 composite provides the wrist contact surface, eliminating a two-shot injection mold for design review. Restricted substance screening for the printed assembly follows RoHS 2011/65/EU Annex II by XRF on the finished part, while raw resin lots are reviewed against the REACH Regulation (EC) No 1907/2006 SVHC Candidate List. The A80 jetted volume ratio is not user-editable; the machine controls the CR-BK-to-CE-NT deposition ratio to maintain nominal Shore A 80, and transition zones between rigid and flexible regions are controlled by the build software to reduce a sharp overmold bond line. Processing on the ProJet MJP 5500X places the electronic retention features away from the main support contact surfaces, and support removal is followed by 24 h conditioning at 23 ± 2 °C and 50 ± 5 % RH. Snap-fit insertion force is then measured on the actual printed frame to assess whether the CR-BK rigid region tolerates repeated assembly. Because the composite is an acrylic photopolymer, prolonged contact with isopropyl alcohol, aggressive ketones, or vapor degreasing solvents used in some electronics cleaning lines may cause surface crazing or softening; a compatibility trial per ASTM D543 is required before introducing any solvent cleaning operation. Terminal parts include smartwatch band prototypes with integrated rigid lugs, overmolded earbud case prototypes, and wrist-worn medical tracker enclosure prototypes.

When a Handheld Diagnostic Prototype Needs a Soft-Touch Grip Without Mold Tooling

The difference between this digital-material approach and a discrete overmold appears at the transition between the rigid CR-BK shell and the A80 grip zone. In a two-shot overmolded prototype, the bond line is created by sequential polymer injection and can fail under shear below the bulk elastomer tear strength. With the A80 composite printed on the ProJet MJP 5500X, the printer interleaves the two base resins at a controlled transition zone, reducing the sharp mechanical boundary. For limited skin-contact handheld medical prototypes, the printed article is evaluated for cytotoxicity per ISO 10993-5:2009 and irritation per ISO 10993-23:2021; sensitization screening per ISO 10993-10:2010 is added when extended-contact human factors testing is planned. The formulation addition ratio is fixed in the RBK-ENT-A80 profile, so softer grip zones are produced by selecting a lower Shore A digital material profile rather than by diluting or post-curing the composite. Support removal is followed by neutral detergent washing and a distilled water rinse, then drying at 40 °C for 2 h. If ethylene oxide sterilization is used for hospital simulation, the material must be re-evaluated after the maximum intended cycle count because repeated exposure can alter surface tack and extractables. The composite is not suitable for implant or long-term mucosal contact applications. Terminal parts include diagnostic probe housings with soft grip inserts, surgical instrument handle form models, and training simulator handpieces.

When a Cobot End Effector Requires Both Rigid Mounting and Elastomeric Compliance

Collaborative robot end-effectors use the CR-BK rigid regions for bolt-on adapters and the A80 composite for pads that conform to part variation during pick-and-place. The printed pad hardness is verified on a flat coupon with ASTM D2240-15(2021), and compression set is measured per ASTM D395-18 Method B at 23 °C for 72 h to assess recovery after storage in the closed gripper position. The A80 ratio is not varied across the pad thickness; when a softer contact is required, the design is changed to a thinner elastomer section or a lower Shore A material profile, not by adding plasticizer or softening additives. The ProJet MJP 5500X build is oriented with the rigid mounting face toward the build plane to minimize support contact with the flexible contact pads. Support removal in the standard heated oil bath must be followed by thorough detergent washing because residual oil on the A80 surface can increase surface slip and reduce friction on gripping pads; a friction comparison can be run per ASTM D1894 if the end-effector specification includes a static friction requirement. Published data for dynamic fatigue of this composite in blocked-gripper or collision-tolerant cobot applications is limited, so cycle testing on the actual end-effector geometry is required before deployment. Terminal parts include parallel gripper pads, bin-picking suction cup adapters, and bellows prototypes for linear rail covers.

For footwear sidewall, heel counter, and midsole geometry reviews, the A80 composite is used where a soft elastomeric response is needed but production TPU molds have not yet been cut. Abrasion resistance is screened using ISO 4649:2017 Method A, although published data for this specific photopolymer is limited, and test results should be compared to a production TPU reference rather than an absolute specification. The CR-BK-to-CE-NT ratio is fixed at the machine level, so the printed part cannot be tuned for density or rebound; cushioning changes are implemented by adding lattice voids or altering shell thickness. On the ProJet MJP 5500X, the CE-NT component reduces brittleness in flex zones while the CR-BK component raises stiffness in the heel counter and sole attachment regions. After support removal, the prototypes are air-dried for at least 24 h at 23 ± 2 °C; no thermal post-cure is specified, and any additional heat exposure must be validated on thin unsupported lattice struts because excessive thermal input can degrade fine elastomeric geometry. Terminal parts include running shoe midsole prototypes for flex groove evaluation, heel counter prototypes, and sport sandal strap anchor prototypes.

The A80 Composite Is Used in Appliance Door Seal Prototypes Only Where EPDM Tooling Is Not Yet Available

Appliance door sealing prototypes use the A80 composite to print the bulb section while the rigid CR-BK material forms the integrated clip and mounting rail, allowing a complete gasket cross section to be fitted into a sheet metal door channel. Water ingress testing on the assembled prototype is performed according to IEC 60529 IPX4 conditions, and the gasket is checked for compression set after 100 door-closure cycles by measuring section height at defined inspection points. The material ratio is locked in the RBK-ENT-A80 profile, so gasket compression force is controlled through section geometry and interference, not through chemical adjustment; this is a key design limitation when comparing prototypes to production EPDM or TPV gaskets. The ProJet MJP 5500X build is oriented with the mounting rail flat against the build plane to minimize support contact with the sealing bulb. Support removal is followed by warm detergent rinsing and dry air blowing; residual oil is disallowed on the sealing surface because it promotes sliding during closure and may create leak paths. Published data for food-contact suitability is not available for this composite; FDA 21 CFR 177.2600 or relevant regional food-contact evaluations must be performed on the printed article before use in food-contact zones. Terminal parts include dishwasher detergent dispenser gasket prototypes, washing machine door seal prototypes, and control panel gasket prototypes.