Designated for dual-cartridge MultiJet Printing platforms, the 3D Systems VisiJet RBK-EBK-A40 multi-material composite set pairs VisiJet CR-BK, a black rigid photopolymer, with VisiJet CE-BK, a black elastomeric photopolymer specified at Shore A 40 under ASTM D2240. The A40 suffix identifies the elastomer-phase hardness rather than a blend percentage or layer thickness. The product is therefore not a single homogenized resin; it is a two-cartridge material set that allows a single part to contain rigid CR-BK domains and elastomeric CE-BK domains without secondary assembly or adhesive bonding.

In the supplier’s MultiJet Printing material scheme, VisiJet CR-BK functions as the load-bearing phase and VisiJet CE-BK functions as the compliant phase. The two phases are jetted from separate printhead channels, planarized, and ultraviolet-cured in the same layer sequence. This spatial material architecture defines the performance envelope: the rigid phase contributes dimensional stability, while the elastomer phase contributes recoverable deformation only within its strain limits. A single bulk modulus cannot be used for the entire part.

Usage categories follow from this phase contrast. The elastomer phase is intended for sealing, cushioning, and flexible living-hinge functions; the rigid phase is intended for dimensional reference surfaces, threaded bosses, snap-fit hooks, and structural load paths. Combining them in one build is specified where the alternative would be a multi-part assembly with bond-line variability. The material set is not a general-purpose replacement for either single-phase VisiJet product when the part function requires only one phase.

Property Benchmarks That Define the Rigid and Elastomer Constituents

Mechanical values are generated on test specimens built in the orientation recommended by the supplier. Because MultiJet Printing deposits material in discrete layers, mechanical properties can exhibit z-axis anisotropy. The datasheet values are therefore orientation-specific. For composite parts, the boundary running perpendicular to the z-axis can have different strength from the boundary running in the x-y plane. This anisotropy is not captured by single-phase coupons and must be considered in design reviews.

Datasheet values for the individual phases are derived from specimens conditioned under ASTM D618 at 23 ± 2 °C and 50 ± 5 % relative humidity. Because the elastomer phase is Shore A 40, its compressive and tensile stress-strain response is non-linear; engineering constants developed for rigid photopolymers cannot be substituted. The supplier’s current technical datasheet remains the reference for exact numerical values, as product revisions and cartridge formulations may shift the reported range. Published data for the transition interface between VisiJet CR-BK and VisiJet CE-BK is limited; interface peel and shear strength should not be assumed equal to bulk phase values.

In a production environment, the two-cartridge set is loaded into a multi-material MJP printer with separate material channels. The cartridges are machine-keyed to prevent material-type errors, and the build chamber temperature is maintained within the printer manufacturer’s operational window. After each jetting pass, a planarization station removes excess material; this station also functions as a cross-contamination control point because black-pigmented resin from one channel can be carried into the other if purge volumes are insufficient. Observed field failure modes include streak formation at the phase boundary and localized soft spots when residual rigid resin is not fully purged before the elastomer channel opens.

The two materials are not mixed in a vat; they are jetted side-by-side from adjacent printhead channels. Jetting stability depends on the viscosity of each black photopolymer at the build chamber temperature. The black pigment in both phases attenuates ultraviolet light more than clear or white counterparts; as a result, cure-dose windows for black materials can be narrower. The energy setting validated for clear or white VisiJet materials is not directly transferable to the black multi-material set. A partially clogged nozzle cannot be compensated by the adjacent channel; it produces a line defect that is not detected until after support removal.

What Part-Design Rules Change When CR-BK and CE-BK Are Combined in One Build?

Because the material set creates a process-dependent interface rather than a discrete adhesive bond, design rules for multi-material MJP parts differ from single-material photopolymers. The transition from rigid to elastomer is generated by pixel-level material assignment in the printhead, followed by ultraviolet curing. At the boundary, unpolymerized or partially cured resin can remain if the exposure dose is reduced by black-pigment absorption. Thin rigid bosses over large Shore A 40 pads should be supported by fillets and drafted walls; otherwise the elastomer phase may tear during demolding or support removal under peel stresses.

The material set is not a substitute for a mechanically fastened insert. When a CR-BK region is used as a clamping flange over a CE-BK gasket, the allowable compressive stress must be derived from the elastomer phase, not from the rigid flange. Because the elastomer is Shore A 40, bolt preload can easily exceed the point at which the sealing lip loses recoverability. Published data for this specific composite configuration is limited; a preload validation using ASTM D395 compression set or ASTM D575 compression-deflection testing at the intended temperature is required before fastener torque is fixed.

Features that cross the material boundary should be designed with a gradual transition or a mechanical interlock; a butt joint in the z-axis has limited interfacial shear area. In sealing applications, the elastomer lip should be compressed against the rigid seat rather than being peeled away from it. Peel loading at the interface is the most common failure mode observed in multi-material prototypes because the cured photopolymer transition zone is thinner than the bulk material. Lattice transitions or perforations in the rigid phase can be used to anchor the elastomer phase during build and service. If the rigid phase contains blind holes, wax can become trapped and exert pressure on the elastomer phase during support removal.

When Wax Removal, Solvent Contact, and Thermal Deflection Interact in Composite Parts

The support material used in MultiJet Printing, typically VisiJet S400, is removed after the build by a heated support-removal process. This step is the dominant thermal cycle for RBK-EBK-A40 parts. Because the elastomer phase has a lower heat deflection temperature than the rigid phase, support-removal temperature must be held below the thermal softening point of the Shore A 40 phase, or residual stress will produce sag in thin membranes and distortion in sealing lips. The rigid phase can survive a higher temperature, but the composite part cannot be processed as if it were pure VisiJet CR-BK.

Wax removal from the composite part is not a bulk melting process alone; it involves diffusion and displacement through channels. The elastomer phase has a higher coefficient of thermal expansion than the rigid phase. During heating, differential expansion can separate the interface and permit molten wax to wick into the gap. Once wax is present in the interface, it acts as a release layer and reduces structural strength. For this reason, post-processing validation should include cross-sectioning a sacrificial part from the same build batch to inspect interface quality before functional testing.

After wax removal, the part is generally rinsed in a post-processing bath. The elastomer phase may swell in hydrocarbon or chlorinated solvents, while the rigid phase may stress-crack in polar solvents. Chemical resistance must be validated to ASTM D543 before the part is placed in contact with fuels, brake fluids, strong alkaline cleaners, or ketones. Steam autoclaving is not a suitable cleaning method for this material set because the thermal load exceeds the deflection temperature of the elastomer phase. Moisture exposure is also phase-dependent: the elastomer region absorbs water at a different rate than the rigid region, and the resulting differential swelling can raise the roughness of the bonded interface. Parts should be conditioned to mass equilibrium under ASTM D618 before metrology or sensitive sealing tests.

Compared with single-material VisiJet CR-BK, the RBK-EBK-A40 cartridge set adds an elastomeric phase with Shore A 40 hardness, but it also introduces a lower thermal limit and additional interface validation. Compared with single-material VisiJet CE-BK, the paired set permits rigid mounting features, threaded bosses, and dimensional reference surfaces that an all-elastomer build cannot provide under clamping loads. Compared with assembling separately printed rigid and elastomer components, the multi-material set removes the secondary adhesive bond but creates a cured photopolymer transition whose peel and shear capacity must be tested for the application.

The datasheet does not provide a universal finished-part compliance declaration. A compliance matrix should be assembled from the following methods when the part is destined for medical, electrical, or industrial service.

For REACH and RoHS, the supplier’s safety data sheet and product stewardship documentation identify the mixture-level hazard classification and restricted substance status. These documents are lot-specific where formulation changes occur; a finished-part risk assessment must consider post-cure residues, support-wax residues, and any cleaning solvent retained in the elastomer phase.

Storage and handling boundaries are equally phase-specific. Cartridges should be stored in the orientation and temperature range stated on the supplier’s cartridge label; exposure to direct sunlight or elevated temperatures can trigger premature viscosity drift and jetting instability. At the manufacturing line, the largest source of batch-to-batch variance in a multi-material build is incomplete purge between the two black resins. Operators should follow the printer maintenance interval for the planing station and purge channels; a single missed interval can generate streaked interface regions that do not appear in visual inspection until the part is cross-sectioned. The maximum allowable service temperature for a composite RBK-EBK-A40 part is governed by the elastomer phase, and the applicable value should be read from the product technical datasheet rather than inferred from the rigid phase HDT.