The VisiJet RCL-ENT-D55 composite is processed as a two-phase jetted solid rather than as a homogeneous resin blend. VisiJet CR-CL 200 supplies the hard transparent phase and VisiJet CE-NT supplies the low-durometer elastomeric phase. The downstream value of this combination is not in the average properties of the two materials but in the shape and continuity of the voxel-resolved boundary between them. Each application below is therefore described by the geometric function of the hard phase, the sealing or dampening function of the soft phase, and the failure mode at the transition. Published product-specific data for the composite is limited in several of these applications; where a numerical threshold is not available from the supplier, the text identifies the appropriate test standard instead.

What happens when a low-durometer seal bead is jetted directly onto a rigid transparent retainer?

The most frequently tested configuration in low-pressure fluid handling uses a flat CR-CL 200 flange as the compression limiter and a raised CE-NT bead as the sealing lip. The hard phase prevents over-compression of the soft bead and carries the tightening torque of the closure screws. Compression set is the controlling property and it must be measured on a coupon that includes the same bead height and hard-floor thickness as the production part, not on a bulk CE-NT slab. ASTM D395 Method B is the appropriate reference; the standard specimen is compressed to a fixed deflection for a specified time and temperature. Production-scale multi-material jetting shows that a hard floor reduced to the final voxel layer at the edge of the build can flex under clamp load and change the compressed cross-section. A screw boss placed too close to the bead can split the soft phase during thread-forming insertion; a hard-phase ring around every threaded insert is therefore an operational requirement. If the assembly is exposed to hot water or water-glycol, the elastomeric phase should be assessed for hydrolysis and compression set because published data for this composite under continuous high-humidity service is limited. ASTM D471 immersion testing is the accepted reference for that exposure. The solvent cleaning step after printing must remove uncured low-viscosity species from the bead root. Residual uncured resin left in the sharp corner between the hard floor and the soft bead can migrate during storage and reduce interfacial adhesion. The phase boundary in this application is not a cosmetic line; it is the primary leak path.

Rigid transparent inspection windows framed by CE-NT seal lands

In flow-cell development, CR-CL 200 serves as a clear sight glass and CE-NT forms the surrounding gasket. This removes a separately die-cut gasket and allows the seal land to sit flush with the window. The main process conflict is optical haze at the mixed-phase boundary. Soft-phase oligomers can diffuse into the uncured hard-phase voxel before UV cure, producing a scattering zone that is not always captured by an average transmittance test. ASTM D1003 measures total light transmittance and haze; the boundary region must be sampled separately because the clear centre can dominate the integrating-sphere reading. Hot alkaline or strongly polar cleaning solutions attack the interface by swelling the elastomer more than the hard phase. The result is a fine wedge-shaped crack that propagates under fluid pressure. To limit this mode, the hard-phase wall adjacent to the elastomeric land should maintain a constant cross-section and the land should be placed away from the flow edge. Planing direction also changes the striae pattern in the transparent hard phase. Horizontal and vertical builds should be compared as witness samples after the same cleaning and drying cycle used for the production part. If the flow cell is autoclaved, dimensional change at 134 °C for 3 min should be recorded and the seal force checked. Published data for optical transmission of the composite interface is limited, so build-orientation-specific inspection is required before the window is used in a critical leak-tight test.

Consumer wearable housings make a different use of the same phases: the clear phase carries the display rim and snap bosses while the CE-NT phase forms the strap loop and cushion. This moves bending stress into the low-modulus phase, but the highest structural risk is at the hard-soft boundary. Repeated loop flexing does not reproduce the delamination mode seen in two-shot overmoulding because the phases are interleaved over a finite transition rather than joined at a sharp melt line. The failure mode is more often a crack in the thin hard shell at the root of the loop or an elastomer tear around a discrete boss. Strap retention testing should therefore include cyclic flexure at the service angle rather than a single proof load. Tear resistance of the soft phase is measured by ASTM D624 die C using a 2.0 mm specimen thickness. Batch-to-batch variation in loop rebound may exceed the nominal Shore durometer range because the surface layer is sensitive to part spacing and build orientation. First-article inspection with micro-CT is advisable when the hard boss is reduced to only a few voxel widths, because the interfacial boundary can become continuous with the outer surface. A continuous hard rim is stiffer but can concentrate stress at the snap feature; a discrete boss layout isolates the snap but lowers the margin against elastomer tearing. Both layouts should be tested under low-temperature flexure because the low-durometer phase hardens and the interface can become brittle at sub-zero service temperatures.

When the composite substitutes for two-shot TPU in appliance connector strain relief

Appliance connector strain reliefs are sometimes prototyped from this composite when the production design is a two-shot thermoplastic polyurethane overmould. The CE-NT phase is used as the cable grommet and the CR-CL 200 phase is the cable stop and housing. Tear strength becomes a design constraint because the cable groove can split along the interface if the groove root is too close to the hard phase. ASTM D624 die C is preferred over tensile elongation for this comparison. The hard phase should form a continuous shoulder behind the CE-NT grommet. If the shoulder is perforated to reduce build volume, the elastomer can bulge through the openings under cable side-load. Torque-on-torque off response is another process interaction: the surrounding elastomer damps the seating torque, so the screw may reach its friction torque before the clamp bottoms on the hard stop. A hard-phase collar that creates a solid clamp bottom eliminates this ambiguity. Chemical exposure is dominated by household cleaners, grease, and plasticiser migration from adjacent PVC cables. The low-durometer phase may swell from low-polarity ester plasticisers; published compatibility data for this specific pairing is limited. Accelerated testing under IEC 60335-1 is required before functional boiling-water or baking tests. Continuous-load creep should be measured by residual clamping force over time rather than by short-term Shore hardness. The replacement of a TPU grommet with a jetted elastomer is therefore not a simple Shore matching exercise; the failure mode is controlled by the interface, the post-processing schedule, and the holding geometry.

The standards matrix below separates the test requirements by phase and failure mode. It is not a substitute for supplier data.

Anatomical models and surgical rehearsal fixtures use the soft phase for compressible tissue regions and the hard phase for transparent osseous or vascular landmarks. These are not implant applications. The material combination has not been qualified as a permanent implant; ISO 10993-5 cytotoxicity screening alone is not sufficient for tissue-contact clearance. The main downstream tests are puncture resistance, suture retention, and reusability after high-level disinfection. The elastomer phase can absorb quaternary ammonium compounds and swell slightly after repeated soak cycles, changing the haptic response of the tissue-like regions. For fluid-filled models, the interface between the transparent hard vessel wall and the soft tissue analogue is the most likely failure position once internal pressure exceeds the peel resistance of the mixed voxel layer. No product-specific peel-strength value is published for this configuration; representative witness patches should be tested with the same orientation and cleaning protocol. Autoclave exposure at 134 °C for 3 min can relieve process stresses and cause warpage in thin hard-phase shells. Ethylene oxide may be less thermally damaging but requires longer aeration because the soft phase can retain residual sterilant. Radiation sterilisation may shift the transparent phase colour; if colour stability is relevant, samples should be exposed to the intended dose and evaluated by ASTM D2244. Because the composite is intended for visual and tactile reproduction rather than mechanical certification, bulk mechanical values should not be interpreted as implant-grade material data.

Floating rigid bosses inside an elastomeric pad shift the failure locus from shear tearing to interfacial peel.

Equipment feet and handheld tool grips sometimes use isolated CR-CL 200 bosses embedded in a CE-NT pad. The bosses carry threaded fasteners or magnetic inserts, and the soft phase supplies damping and surface friction. The transition from bulk elastomer shear to interfacial peel appears when the boss diameter is reduced and the circumferential contact line becomes the dominant load path. In a cast or injection-moulded pad, the hard boss is held by a moulded undercut. In a jetted composite, the boss must be held by the drop-placement interface itself. Pull-out force is therefore a function of total interfacial area and local cure state at the transition. A straight cylindrical boss will exhibit lower pull-out than a boss with a dovetailed or flanged root, because the dovetail transfers load into compression rather than pure peel. Tensile testing of the bulk hard phase under ASTM D638-14 Type IV specimens does not capture this boundary. For dynamic loading, dynamic mechanical analysis at 1 Hz under ASTM D4065 is a more sensitive method for interfacial energy differences than quasi-static pull-out alone. The low-durometer phase should not be bonded permanently with aggressive cyanoacrylate adhesives because the boundary may whiten and plasticise. If the pad is loaded at high frequency, hysteresis in the elastomer can raise local temperature; published data for this composite under cyclic compressive loads is limited. The practical design rule is to extend the rigid boss through the full pad thickness to the mounting face, isolating the fastener from the elastomer and changing the failure mode from peel to bearing.

Underhood retainer clips and sensor mounts are another application where the rigid phase holds a locating feature and the elastomer provides vibration damping. The primary process constraint is high-temperature dimensional stability. The hard phase may creep if the clip is installed near a heat source; the soft phase can undergo thermal ageing and lose its clamping force. ISO 75-2 defines heat deflection for the hard phase; the elastomeric phase should be evaluated by compressive stress relaxation rather than hardness retention because Shore hardness may recover after cooling. Engine-bay exposure includes hot air, coolant spray, and oil mist. The interface can wick fuel or oil if it opens at the edge; this is a stronger reason to encapsulate the entire boundary than the pure pull-out force. Published multi-material jetting data for continuous automotive underhood exposure is limited, so prototype clips should be tested with thermal cycling between sub-zero and elevated temperatures in the intended mounting position. The best-performing geometry in limited published service studies is a full-depth hard boss capped by the elastomer only on the outside face, rather than a soft pad with embedded hard islands. That configuration avoids exposing the phase boundary to the hot mounting surface and reduces edge wicking. Electrical connector clips should be tested for dimensional recovery after repeated insertion and withdrawal and after each thermal cycle; the low-durometer phase may retain a temporary set that increases clip insertion or removal effort.