VisiJet RWT-ENT-A70 is a multi-material photopolymer composite supplied for MultiJet Printing systems. Its composition combines two VisiJet feedstocks: VisiJet CR-WT 200, a rigid white photopolymer, and VisiJet CE-NT, an elastomeric natural photopolymer. The designation A70 identifies the nominal Shore A durometer of the printed composite when tested according to ASTM D2240. The material is not a copolymer; it is produced by voxel-level co-deposition of the two resins in a single build. This creates spatial control of compliance and rigidity without insert molding, adhesive bonding, or secondary assembly. The composite is intended for the ProJet MJP 2500 Plus platform and comparable multi-material MJP systems that support simultaneous rigid and elastomeric material channels.

Published mechanical data for the exact RWT-ENT-A70 configuration are derived from Type IV tensile specimens and Shore A plaques printed in the XHD mode of the MJP 2500 Plus. Because the composite is a spatially graded material, values measured on single-material tensile bars do not capture the full behavior of an interpenetrating interface. For design purposes, the composite should be characterized on the same voxel pattern and wall thickness that the production part will use; published data for this specific configuration is limited outside the manufacturer’s technical bulletin.

Processing through the ProJet MJP 2500 Plus Multi-Material Channel

Layer formation in the MJP process deposits photopolymer droplets at controlled resolution and then UV-cures them in the presence of a wax support. In multi-material builds, the printhead switches between CR-WT 200 and CE-NT channels according to the volumetric assignment defined in the build file. The rigid phase provides dimensional anchorage, while the elastomer phase provides recoverable deformation. The interface is not a mechanical interlock; it is a photopolymer network formed by adjacent cured voxels. Bond integrity depends on cure exposure per layer, material jetting sequence, and the absence of uncured monomer at the transition. Because CE-NT and CR-WT 200 have different shrinkage factors, a stepwise transition from 100% rigid to 100% elastomer over a defined distance reduces stress concentration at the interface. A transition length below 1 mm can produce visible notch lines and lower tear resistance along the boundary; manufacturer process guidance recommends a graded transition zone that distributes the modulus differential across at least 2 mm in parts with dynamic flexural loads.

Support removal for the composite follows the standard MJP wax-removal sequence: low-temperature wax melt, ultrasonic oil bath agitation, and then a water wash with compatible surfactant. The CE-NT phase absorbs bath fluids more readily than the rigid phase, particularly in thin walls below 1 mm. Drying to constant mass after cleaning is required before durometer or tensile testing. Residual support wax in the elastomer phase can reduce tear strength by plasticization; the effect is measurable with ASTM D624 Type C specimens conditioned at 23 °C and 50% relative humidity. Published process bulletins recommend post-wash air drying at 25 °C for at least 12 hours for parts with elastomer thickness above 5 mm.

What Limits Interfacial Tear Strength in Elastomer-Rigid Transitions?

Two competing effects control dimensional stability in RWT-ENT-A70 parts. First, the low glass transition temperature of CE-NT allows stress relaxation at room temperature, which reduces interfacial stress but also permits creep under sustained load. Second, the rigid CR-WT 200 network restricts lateral contraction of the elastomer phase during tensile loading; this constraint increases the apparent modulus at the interface but lowers elongation at break. The composite is therefore not a simple arithmetic mean of its components. When tensile specimens are printed with a 50/50 volumetric distribution, the measured stiffness in thin sections is closer to the rigid phase than to the elastomer phase because the continuous rigid network controls the deformation. Published data for this specific configuration is limited, but the Shore A 70 nominal value indicates that the composite is elastomer-dominated at the surface while load-bearing paths may remain rigid.

In parts with repeated flexure, the interface is the critical flaw population. Rubber-phase tearing in overmolded flexures usually initiates at the edge of the rigid reinforcement where stress triaxiality is highest. A fillet radius below 0.5 mm around the rigid boundary has been observed to reduce the number of flex cycles before visible crack initiation when tested under a 25 mm/min crosshead rate. The same geometry under slower cyclic loading shows more blunting, but creep accumulation in CE-NT shifts the neutral axis. Because CE-NT has a low elastic modulus, strain concentrations at geometric transitions must be estimated with a hyperelastic material model; linear elastic assumptions overestimate peak stress in the elastomer phase by more than 40% at 50% nominal strain.

Comparative values below are collated from manufacturer technical publications and follow the cited test standards. Values should not be used as design allowables without part-level testing on printed coupons with the same build orientation and wall thickness.

For load-bearing applications, the limiting mechanical criterion is usually not the Shore A durometer but the creep resistance of the CE-NT phase. The elastomer component has a low tensile modulus; under a continuous 0.1 MPa load, thinner sections exhibit time-dependent strain. Creep test data following ASTM D2990 are not consistently reported for the composite, so designs that impose static loads on elastomeric sections should include prototype validation. The CR-WT 200 phase carries compressive and bending loads effectively, but once a crack reaches the interface from the elastomer side, propagation can continue along the rigid surface if the interface lacks a graded transition.

When the Part Envelope Contains Both 70A Contact Pads and 2,000 MPa Reinforcements

The multi-material capability of the MJP 2500 Plus enables a single build to contain low-durometer contact pads and high-stiffness mounting bosses. The printed part can replace an injection-molded overmold assembly in low-volume functional testing. Unlike adhesive bonding of a separately cast elastomer, the voxel-level transition has no defined bondline thickness; the transition width is controlled by the number of intermediate material steps. A wider transition width reduces the peak shear stress at the interface but increases the distance over which the part behaves as a soft material. For tactile buttons and vibration-isolation mounts, the elastomer phase can be localized on the contact surface while the rigid phase extends into the housing. In rotary knobs, the rigid core provides torque transmission and the 70A outer layer provides grip; the limiting torque is set by the interfacial shear strength of the composite, which is lower than the bulk shear strength of either phase. Published interfacial shear strength data for RWT-ENT-A70 are limited; part-level torsion testing is therefore required when the design has a small-diameter rigid core below 10 mm.

Storage, handling, and post-processing of the two-component system must account for the different solvent sensitivities of the feedstocks. The CE-NT phase swells in polar solvents, while CR-WT 200 is more resistant. Assemblies that will contact cleaning agents or oils should be tested under ASTM D471 immersion conditions for volume change and tensile retention. The composite should not be used where continuous service exceeds 40 °C without creep testing because the CE-NT phase loses mechanical recovery as temperature increases. If the application requires autoclaving, the CR-WT 200 phase may retain shape but the elastomer phase may undergo permanent set; published data for steam sterilization of the composite is limited.

Comparing RWT-ENT-A70 Against Standalone CE-NT and CR-WT 200

The principal difference is the absence of a discrete bondline. Standalone VisiJet CE-NT provides lower hardness and higher elongation but lacks a self-supporting rigid structure; standalone VisiJet CR-WT 200 provides high rigidity but cannot absorb cyclic strain. RWT-ENT-A70 places both responses in the same net-shape part. Compared with a rigid print covered by a separately cast silicone layer, the composite eliminates manual mold fabrication and adhesive variability. Compared with a digital elastomer-only print, the composite increases resistance to buckling under compressive force because the rigid phase reinforces thin sections. This is not a universal improvement: the product is fixed at nominal Shore A 70, while CE-NT is substantially softer. In applications requiring Shore A 30 to 50, the composite may be too stiff, and alternative digital materials or manual overmolding should be considered.

For production-scale manufacturing lines, the main processing bottleneck is support removal time for thick elastomeric sections. Ultrasonic bath dwell times increase when the CE-NT volume fraction exceeds 50% because wax residue remains trapped in compliant undercut regions. Batch-to-batch variance in the rigid feedstock is low relative to the dimensional scatter introduced by part orientation; tensile strength measured in the Z orientation can fall below the XY value by more than 20%. These effects are consistent with layerwise photopolymer anisotropy and must be incorporated into tolerance stacks and mechanical margin calculations.