3D Systems VisiJet RWT-EBK-A50 Multi-Material Composites is a two-cartridge UV-curable photopolymer material set consisting of VisiJet CR-WT 200** and VisiJet CE-BK. The set is order-coded for multi-material MultiJet Printing on the ProJet MJP 2500 Plus platform and is not interchangeable with single-cartridge MJP rigid-white or stand-alone elastomer sets. The A50 suffix in the designation is used as a target Shore A50 durometer for digitally mixed regions, evaluated under ASTM D2240-15e1. VisiJet CR-WT 200** supplies the rigid white phase with comparatively high flexural stiffness and dimensional accuracy, while VisiJet CE-BK supplies the black elastomeric phase with recoverable strain and tear resistance. The two materials are contained in sealed, RFID-tagged cartridges that the printer recognizes separately; this prevents cross-loading between the rigid and elastomeric reservoirs. During job preparation, a part file can be segmented by region or grayscale mask so that rigid, elastomeric, and intermediate-durometer zones are produced inside one build cycle without inserting pre-molded components.

Material handling for this set follows the cleanliness and light-exposure controls required for UV-curable MJP resins. Cartridges should be stored in the temperature window stated on the safety data sheet, typically 15–30 °C, and protected from sunlight and fluorescent UV emission. Before a build, the operator verifies the mixed-material license, firmware revision, cartridge identification, and support-material level. The ProJet MJP 2500 Plus maintains separate heated feed paths for the rigid white photopolymer, the black elastomeric photopolymer, and the wax support. In the print zone, a planar jetting array deposits the fluids and UV lamps cure each layer. The software translates the three-dimensional material map into voxel-level ratios; no physical mixing occurs inside the reservoir. Because the two phases are jetted through separate channels, nozzle defects tend to affect one material class at a time. A rigid-phase void can reduce short-beam shear response at structural skins, while an elastomeric-phase void can create a tear-initiation site when the part is strained. Production-scale observation of mixed-material MJP platforms indicates that thin elastomeric ribs can distort during support-wax melt-out if oven temperature or cycle time exceeds the manufacturer’s validated post-processing envelope. The support-removal oven and cleaning bath should therefore be maintained according to the printer manual, since residual wax and resin on fixtures can alter heat transfer and contribute to batch-to-batch hardness scatter.

What property boundaries govern the two starting materials?

The rigid white phase, VisiJet CR-WT 200**, is characterized by tensile testing under ASTM D638-14 or ISO 527-2:2012, flexural testing under ASTM D790-17, and heat deflection under ASTM D648-18. The elastomeric black phase, VisiJet CE-BK, is characterized by tensile stress-strain response under ASTM D412-16 and tear strength under ASTM D624-00. The mixed A50 condition is measured with a Type A durometer under ASTM D2240-15e1. Lot-specific property values appear in the certificate of analysis and the manufacturer’s product datasheet; those values should not be transferred to a design without matching build orientation, post-cure schedule, and part thickness. The important boundary condition is that the rigid phase has a continuously higher modulus and lower elongation than the elastomeric phase. The mixed material is not a single homogeneous polymer network: it is a printed digital composite in which the short-range mechanical behavior is governed by the spatial arrangement of cured resin voxels and the localized volume fraction of each component.

The transition zone between rigid and elastomeric regions requires particular attention when a part is loaded across the interface. A sharp material boundary can concentrate tensile strain at the phase change and promote early crack initiation below the rigid-phase tensile limit. In prototype grips, seals, and overmolded enclosures, a gradient width of 2–5 mm is often used to redistribute stress, but the optimum width depends on local cross-section, loading mode, and build orientation. The interface is formed during sequential layer cure rather than by melt-overmolding; therefore, its peel strength is influenced by overlap area, UV exposure, and interfacial roughness. Published data for this specific configuration is limited, so validation under ASTM D903-98 or ISO 11339:2022 is recommended before replacing a mechanically fastened or adhesively bonded assembly in service.

Control of Shore A gradient drift in finite production runs

Shore A readings taken on mixed-material blocks are not perfectly uniform across every build position. Heat accumulation, UV lamp aging, and printhead stagger create local differences in cure dose that can shift measured hardness by several points under ASTM D2240-15e1. Onboard calibration and material-temperature control minimize this drift, but operators can detect it by placing duplicate hardness coupons at multiple positions in the build envelope. Equipment audits on MultiJet Printing platforms have recorded lower hardness at the outer edges of the platen when UV irradiance falls below the central maximum; this effect is more visible in mixed materials than in single-phase rigid white because the elastomeric component is more sensitive to undercure. To maintain traceability, the build file should include coupons with the same rigid-elastomeric ratio, layer thickness, and post-cure schedule as the production parts. The resulting measurements should be compared against the target Shore A50 value and against a locally established moving range, not against an external hardness specification intended for homogeneous injection-molded elastomers.

CAD preparation for this material set differs from single-material MJP because the part file must contain discrete or gradient assignments that the build software can translate into material volume fractions. If a graded region is created by Boolean subtraction of two overlapping bodies, the exported mesh may contain non-manifold edges that confuse the slicing software. The preferred workflow uses a single solid with region masks, or an assembly with no interpenetrating bodies. The software assigns the more rigid material to the structurally loaded core and the elastomer to the contact surface. Thin coatings below the minimum voxel resolution may not produce the intended durometer because layer thickness and support boundaries dominate the effective composition. Prototype sealing lips with a thickness below 1 mm require verification because cleaning and handling stresses can tear the elastomeric phase before functional testing. The target Shore A50 applies to a sufficiently thick mixed section, not to a skin effect at the part surface.

Typical multi-durometer applications include robotic gripper jaws, handheld instrument housings, gasket prototypes, cushioning mounts, and consumer-product overmold mockups. In these applications the rigid white component provides screw-boss retention, locating features, and resistance to frame deflection, while the black elastomer provides a conforming surface that distributes grip force or seals against low-pressure contact. The material set is not rated for sustained high-pressure seals because the digital mixed zone may creep or cold-set under compression. Compression set testing under ASTM D395-18 and tensile creep data under ASTM D2990-17 are required before industrial sealing commitments are made. Chemical compatibility should be evaluated under ISO 175:2010 when exposure to hydrocarbons, esters, ketones, or dilute acids is expected. Where the manufacturer’s chemical resistance chart does not list a specific fluid, an immersion trial is necessary before operational use.

When the set is compared with single-cartridge VisiJet rigid or elastomer materials

The operational difference is that single-cartridge materials such as VisiJet M2R-WT rigid white or VisiJet CE-BK elastomeric black used alone force a part to be produced with one hardness class. RWT-EBK-A50 combines the two endpoints inside the same build, so the user can place a rigid white clamp frame and a soft black sealing lip without postoperative bonding. This differs from multi-shot injection molding because the digital blend can be specified with continuous spatial variation and because prototype changes do not require new tooling. It also differs from printing a rigid substrate and then casting silicone onto it because the MJP process handles both materials in one machine and uses a single support-removal route. The limitation is that the mixed regions are not a homogeneous thermoset elastomer with the full molecular network of a cast polyurethane or liquid silicone rubber. Mechanical properties are anisotropic and may show lower tensile strength at the Z-axis interlayer plane. Users should therefore test printed coupons in the same orientation, thickness, and cleaning cycle as the final part under ASTM D638-14 or ASTM D412-16 rather than relying exclusively on isotropic datasheet values.

Compatibility and cleanliness constraints are especially important for mixed-material builds. The cartridge set is not formulated for the ProJet MJP 2500W unless the machine configuration and license are explicitly validated. The black elastomeric phase is not a generic mixing base for other VisiJet materials. Introducing isopropanol, acetone, or water into the cartridge can destabilize the photopolymer and lead to phase separation or inkjet nozzle failure. Open cartridges exposed to ambient light may form gel particles that obstruct the printhead filter and create localized banding in the rigid white areas. Waste streams containing uncured resin and support wax should be segregated according to the safety data sheet and applicable REACH/RoHS requirements. The product documentation identifies the material set as intended for industrial and laboratory use; it is not a food-contact material unless a specific migration test under the relevant national or regional regulation has been performed and documented. USP Class VI or ISO 10993-5 cytotoxicity data must be requested from the manufacturer when required, because standard technical datasheets do not imply such qualification.

Post-processing for RWT-EBK-A50 gives the best dimensional agreement when support wax is removed using the printer’s validated heat-and-clean protocol. Manual scraping of soft elastomeric regions is not recommended because it can tear the black phase or create local surface differences that are not representative of the bulk material. The elastomeric component can absorb cleaning oil if left in the cleaning bath beyond the specified time, temporarily reducing Shore A hardness and increasing part weight. Conditioning under laboratory ambient conditions for 24–48 h before hardness testing is a common comparison rule when validating against ASTM D2240-15e1, although the manufacturing batch protocol should be followed for release decisions. The rigid white phase can be machined, sanded, and primed for coating, but the soft black phase may deform under aggressive mechanical polishing. Rotary tooling should be evaluated on a scrap part first because local heating can soften the digital mix and produce smearing at the transition boundary.

Long-term storage stability of the two-component system depends on lot age, temperature history, and exposure to light. The manufacturer prints an expiration date on each cartridge; material beyond expiration should not be blended with fresh material because viscosity drift can alter drop formation and layer thickness. If the printer will be idle, the printhead should be purged according to the system maintenance procedure. The black pigment in VisiJet CE-BK absorbs UV energy differently from the white phase, so mixed regions near the outer surface may exhibit a different degree of cure than the core. Differential scanning calorimetry of the cured material can show residual exotherm if post-cure is incomplete. Such residual reactivity is relevant when parts are sealed or painted because it can interact with coating solvents. Operators who require stable Shore A values over multiple builds should store cartridges in the recommended orientation and allow them to reach room temperature before installation, because cold resin increases viscosity and can interfere with jetting.

Compared with stereolithography photopolymers, the MJP mixed-material set offers the advantage of regional hardness variation but typically requires more involved support removal and cannot achieve the optical clarity of a clear single-phase resin. Compared with powder-bed or extrusion multi-material processes, MJP can produce finer minimum features, but the build envelope is smaller than typical extrusion platforms. Published independent comparative data for this specific configuration is limited; therefore, any benchmark should include identical build orientation, layer thickness, post-cure time, and cleaning history. The designation RWT-EBK-A50 is an order code, not a chemical formulation statement. Users who need exact glass transition temperatures, tensile modulus, and elongation at break for finite element analysis should request the current material datasheet from the manufacturer and perform their own characterization at the expected service temperature, rather than transferring values from unrelated material generations.