In fluid-handling pilot plants, EBK-ENT-R78 is first evaluated as a two-zone diaphragm pump seal in which CE-BK forms the outer lip and CE-NT forms the convoluted bellows. The two VisiJet elastomer feeds are jetted from separate MultiJet Printing channels, so the material ratio is not established by bulk blending; it is set by the STL region assignment in the digital model. A representative 25 mm diaphragm was built with a 0.8 mm CE-BK lip band and a 2.4 mm CE-NT flexing wall, yielding a volume distribution of approximately 55:45. Build work was carried out on a ProJet MJP 2500 Plus in high-definition mode at 32 μm layer thickness. Wax support removal followed the ProJet Finisher sequence, then ultrasonic clearing in the heated bath with the bellows openings held horizontal so that liquified wax could not re-deposit into the internal cavity. Post-curing was performed under UV-A after the part surface was dry rather than immediately after the bath, because residual bath fluid on the elastomer surface can create localized soft zones. The finished prototype was subjected to cyclic flexure at 1 Hz for 50,000 strokes, with compression set measured according to ASTM D395 Method B and fluid swell measured after 70 h immersion in the actual process fluid according to ASTM D471. The reason for testing in the actual process fluid is that published data for the combined EBK-ENT-R78 configuration is limited, and photopolymer elastomer swell is strongly fluid-specific rather than predictable from a simple hydrocarbon solubility parameter. The terminal downstream object is a pre-production diaphragm seal used to validate lip geometry and bellows wall thickness before the part is converted to injection-molded TPE. This diaphragm prototype is not intended for food-contact service; if such service is contemplated, migration testing under the relevant food-contact regulation must be added.

Soft-Grip Diagnostics Housing Overmolding in MultiJet Printing

The housing shells of point-of-care analyzers have been built with CE-BK as the outer grip skin and CE-NT as the inner cushion core, creating a single print that mimics a two-shot overmolded thermoplastic elastomer assembly. For a handheld analyzer side grip, the digital material ratio was CE-BK 40% to CE-NT 60%, with the black skin held to 1.2 mm and the natural core thickness set to 3.0 mm. The two materials are jetted in the same build without a physical bondline, but the printed interface is not automatically a certified overmold bond; peel strength at the interface should be checked by a method such as ASTM D1876 T-peel before committing to the design. The ProJet MJP 2500 Plus build was oriented so that the grip surface was perpendicular to the Z axis to reduce stair-stepping on the outer shell. Support removal in the deep undercut finger groove required a longer ultrasonic bath cycle than a flat gasket, and after removal the parts were post-cured until the surface was free of tack. Compliance for patient-adjacent use is driven by ISO 10993-1:2018; if cumulative skin contact exceeds 30 min per day, the manufacturer should obtain data for cytotoxicity according to ISO 10993-5 and sensitization according to ISO 10993-10. Published data for this specific CE-BK/CE-NT multi-material configuration is limited; the fact that individual materials may have a biocompatibility file does not eliminate the need for process-specific testing after post-cure. The final downstream product is a diagnostic instrument housing prototype that can be used for drop testing according to IEC 60068-2-31 and for user grip ergonomics trials before injection tooling is cut. The CE-BK outer skin also provides a visually stable black surface, while the CE-NT core allows the designers to see the break line during fit and assembly.

When a Shore A Gradient Replaces Discrete Rubber Isolators

Small stepper motor mounts for portable analytical equipment have been redesigned as a single printed isolator in which CE-BK forms a constraining outer shell and CE-NT forms the load-bearing core columns. The effective material ratio in one 30 mm cylindrical mount was CE-BK 30% to CE-NT 70%, with the outer shell thickness at 1.8 mm and the internal columns at 2.5 mm diameter. The printed isolator was built at a 45° inclination so that the column sidewalls did not exhibit heavy stair-stepping, and the wax support was removed with pulsed ultrasonic clearing because the internal cell gaps were below 2.0 mm. Post-cure was completed before the mount was press-fitted into the motor cradle. Dynamic validation followed IEC 60068-2-6 for sinusoidal sweep and IEC 60068-2-64 for broadband random vibration, with transmissibility measured using an electrodynamic shaker table. Because the two constituents share a nominal Shore A 78 hardness, the design does not produce a true durometer gradient from black to natural; the vibration isolation is achieved by the column geometry and shell constraint rather than by a material hardness differential. This is a critical boundary condition: a multi-material print from CE-BK and CE-NT should not be represented as a multi-durometer elastomer unless the post-cure hardness is mapped on the actual part with ASTM D2240. The terminal downstream part is a stepper motor isolator used to evaluate mechanical amplification at specific drive frequencies, and it may be replaced by a die-cut cellular urethane pad if the printed design produces a transmissibility peak at the carrier frequency.

Vacuum Forming Tooling Requires Sacrificial Elastomer Zones

Thermoforming cells have used the composite for vacuum tooling inserts in which CE-NT forms the bulk base and CE-BK forms a continuous perimeter sealing rib. In a 300 mm by 200 mm tray tool, the digital volume ratio was CE-NT 80% to CE-BK 20%, with the black sealing rib printed at 1.0 mm height and the natural base thickness at 8.0 mm. Vacuum channels were modelled at 0.6 mm diameter and oriented downward during the ProJet Finisher support removal stage, which prevented liquified wax from re-solidifying in the channels. After support removal, the tool was post-cured and then checked for surface hardness with ASTM D2240 before the first forming cycle. The edge bead is sacrificial because the forming sheet applies repeated compressive loading and the photopolymer elastomer can take a permanent set at local temperatures above its continuous-use limit. Published data for the EBK-ENT-R78 multi-material tool in repeated thermoforming cycles is limited, so a thermocouple embedded in the printed tool core should be used during first-run trials to confirm that the tool remains below the supplier-defined continuous-use temperature. The final downstream product is a vacuum forming fixture for medical tray prototypes, and the tool is replaced when the edge bead drops below the dimensional tolerance required for sheet sealing.

Why Regional Durometer Mapping Is Used in Surgical Training Models

In surgical simulation models, the combination of CE-BK and CE-NT is used primarily to create visible anatomical distinction without a perceptible hardness step between adjacent tissues. A liver segment model was built with CE-NT as the parenchymal bed and CE-BK as the vascular tree, with a digital volume distribution of approximately 65:35. The nominal Shore A 78 hardness of both materials is close enough that the tactile response is dominated by geometry rather than by material stiffness; hollow vascular structures do not feel harder than the surrounding natural matrix if the wall thickness is kept below 2.0 mm. The print was performed on a ProJet MJP 2500 Plus at 32 μm layer thickness, and the vessel lumens were aligned with the Z axis to preserve roundness. Support removal from 3.0 mm lumens required a longer ultrasonic bath cycle than the scheduled flat-part cycle, and the thin CE-NT membrane surrounding the vascular tree showed residual tack if bath temperature or wash time was not controlled. For a reusable non-sterile training model, the compliance file normally requires skin-contact safety data, which may include ISO 10993-5 cytotoxicity and ISO 10993-10 sensitization. Because residual support oil on printed elastomer surfaces can be difficult to remove from small lumens, a validated wash protocol is part of the production record, not an optional step. The final downstream object is a hybrid vascular anatomy task trainer used for instrument navigation and clip application exercises; it is not a marketed medical device unless additional regulatory assessment is performed.

Wearable electronics prototypes exhibit a different set of constraints because the part must survive repeated flexing while in contact with skin and cosmetic creams. In this application, EBK-ENT-R78 has been evaluated for a smartwatch strap prototype in which CE-BK forms the outer shell and CE-NT forms the inner skin-contact cushion. The digital material ratio was approximately 50:50, with the CE-BK outer shell at 2.2 mm and the CE-NT inner pads at 1.4 mm. Build orientation was set at a 5° skew from the long axis to reduce step artifacts on the curved outer surface. Support removal from the honeycomb ventilation cutouts was more difficult than for the flat gasket applications because the 1.0 mm cells trapped wax when oriented horizontally; the parts were rotated 90° for a second ProJet Finisher cycle to fully clear the openings. Post-cure was conducted until the surface was free of tack, and the strap was then subjected to flex cycling at 1 Hz for 20,000 cycles as a screening exercise. Formal tensile residual-strength comparison according to ISO 37 remains necessary before the design can be transferred to a production specification. Compliance for consumer electronics focuses on prolonged skin contact, requiring sensitization data according to ISO 10993-10 if the daily contact period exceeds 30 min, and REACH Article 33 communication is required if any SVHC exceeds 0.1% w/w. The final downstream product is a fit-and-wear prototype used to validate strap geometry, buckle retention, and skin comfort before tooling is produced; it is not a certified medical wearable band.