Proto3000 Objet Digital Materials™ DM_7230 Transparent Prototyping Polymer is distributed as a UV-curable acrylic photopolymer for PolyJet multi-material platforms. The DM_7230 designator belongs to the Objet Digital Materials™ family, in which two or more base resin streams are jetted in controlled ratios from separate reservoirs and cured within a single printed layer. This digital blending approach allows the final network to be tuned for transparency and rigidity without requiring a separate premixed vat. The product is intended for transparent prototype parts where inspection of internal channels, light paths, or assembled component interfaces is required before release to production tooling. Machine compatibility is limited to PolyJet systems that accept Objet Digital Materials™ cartridges and have the correct firmware and material license installed. Loading a digital material into an unlicensed system or pairing it with an unsupported cartridge will generate a material verification fault or, if the fault is overridden, may damage the printhead fluid train. The uncured liquid is typically deposited at layer thicknesses of 16 µm or 30 µm, depending on the selected print mode. Published data for DM_7230 across every build mode, carriage speed, and UV-lamp calibration set is limited; therefore process qualification should be repeated after firmware changes, cartridge lot changes, or lamp replacement. The material should be identified by its safety data sheet, resin lot, and printer configuration rather than by nominal visual appearance alone.

Handling and storage of DM_7230 follow the same general controls applied to PolyJet photopolymers: cartridges are kept sealed until installed, the fluid delivery system is purged after extended idle periods, and resin contact surfaces are not mixed with unapproved cleaning solvents. Because digital material blends are formed at the point of jetting, the operator should verify that both source resin cartridges are within their qualified shelf life and that the printer material identification check has accepted the cartridge lot. A resin lot that passes the identification check but has been exposed to temperature cycling may still show viscosity drift. Head temperature, meniscus vacuum, and printhead drop-watch diagnostics should therefore be recorded at the start of each batch.

What governs interlayer diffusion and UV cure depth in DM_7230?

Interlayer strength in DM_7230 is governed by the time between droplet deposition and UV irradiation, the radiant energy delivered to the droplet array, and the diffusion of reactive acrylate species across the layer boundary. The printer firmware controls lamp irradiance, carriage velocity, and the number of exposure passes. If the UV dose is below the qualified threshold, oxygen inhibition at the outer surface leaves an undercrosslinked skin that reduces adhesion to the next layer. If the dose is excessively high or the build chamber temperature is above the specified range, differential cure shrinkage can accumulate across large flat sections and contribute to edge lift or curling. The acceptable dose window is equipment-specific; it is stored in the printer calibration file and is not user-adjustable on standard PolyJet builds. Operators should not attempt to compensate for a dimming lamp by reducing print speed or increasing jetting temperature, because the resulting droplet spread changes layer geometry. A daily drop-watch check, roller and lamp window cleanliness, and head alignment are more reliable controls for maintaining interlayer consistency. Published data for DM_7230 green-state peel strength or interlayer tensile values is limited.

Layer thickness modifies the depth of cure relative to the deposited film. At 16 µm, droplet overlap is higher across the layer plane, which tends to reduce sidewall roughness but increases build time. At 30 µm, the build is faster, but any undercured layer has a larger cross-section available for oxygen inhibition and may show greater anisotropic shrinkage. Switching between these modes should trigger a new dimensional capability study rather than a simple offset change.

Build orientation, gloss modes, and anisotropy in tensile data

Tensile properties of digital material parts are not isotropic. DM_7230 parts printed in the Z direction show different elongation and fracture behaviour from parts printed in the XY plane because the interlayer boundary is a discrete weak plane. ASTM D638-14 tensile specimens should be printed with the gauge length oriented in the intended service direction. If the application is not directional, flat, on-edge, and vertical specimen sets should be reported separately. Glossy and matte build modes also affect the as-printed surface. In glossy mode, a thin sacrificial film is jetted around the part, reducing layer-step visibility but potentially leaving a slightly different surface cure than matte mode. In matte mode, the surface has a fine texture that scatters light and must be sanded, polished, or coated before optical haze measurement. Haze should be measured according to ASTM D1003 using a hazemeter or spectrophotometer on a conditioned specimen of known thickness. Transparent part clarity does not depend solely on bulk transmission; surface roughness and internal void alignment contribute to total scattering. The build style should therefore be recorded alongside mechanical and optical data. Published values for DM_7230 tensile strength, elastic modulus, and elongation at break should be taken from the current supplier datasheet. When the datasheet does not list a value for the chosen build mode, the missing condition should be demonstrated by testing rather than inferred from a similar material.

Support removal for transparent DM_7230 parts is a process boundary. PolyJet supports can be removed with a water-jet station; high-pressure dwell time on clear surfaces can erode fine features and increase haze. If the water-jet nozzle is held too close or too long on a single area, the part surface develops a frost-like roughness. Alkaline cleaning solutions are used on some support formulations, but the part should not be immersed in heated alkaline baths above the support material supplier’s recommended temperature because the residual acrylate surface can soften and lose dimensional accuracy. After support removal, a UV flood post-cure may be applied. The post-cure unit should provide uniform irradiance across the full build envelope; nonuniform post-cure can generate differential shrinkage and warpage in flat transparent plates.

When storage humidity exceeds 60% RH and cleaning solvents contact the part

Humidity control for DM_7230 cartridges is primarily an electronics and connector issue rather than a bulk resin solubility problem. PolyJet cartridges are sealed, but condensation above 60% RH can enter the material bay and settle on the cartridge chimney or fill ports during replacement. If moisture is drawn into the fluid path, it can change local viscosity and produce jetting instability. The printer bay should be kept within the manufacturer’s stated temperature and humidity envelope; if the ambient dew point is close to the resin delivery temperature, cartridge transfers should be delayed. Finished parts can absorb some moisture in humid environments. Dimensional measurements should be recorded at 23 °C and 50% RH after conditioning according to ISO 291. Cleaning solvents are a stronger boundary. Aggressive ketones such as acetone, methyl ethyl ketone, and chlorinated solvents can attack the acrylic network, causing surface crazing or softening. Isopropyl alcohol is commonly used for wipe cleaning; however, prolonged soaking should be avoided unless the supplier’s cleaning protocol explicitly approves it. If fouling from release agents or machining coolants must be removed, a neutral detergent solution is lower risk than aromatic hydrocarbons.

Lamp aging, jet dropout, and the onset of interlayer haze

Process capability for DM_7230 depends on the UV lamp spectral output. PolyJet lamps degrade over service hours; when irradiance falls below the machine calibration limit, the surface remains undercrosslinked and the next layer bonds poorly. A common operator error is to reject parts only when visible delamination appears. By that point, lamp output may already have been marginal for several builds, producing parts with higher internal stress and lower transparency. Roller and wiper functions also affect layer uniformity. If the wiper blade leaves residual resin on the previous layer, droplet coalescence is disrupted and the part can show a distinct band perpendicular to the carriage axis. Drop-watch checks identify missing or misdirected jets; a single missing jet in a transparent digital material produces a linear void that scatters light and becomes visible through the part wall. Such voids are difficult to repair and are not acceptable in optical path prototypes. A documented start-of-shift checklist includes drop-watch, lamp hours, roller rotation, wiper edge condition, and cartridge lot verification.

Drainage design, trapped support, and internal channel clarity

Clear internal channels in DM_7230 prototypes are not automatically clear after support removal. If a channel is fully enclosed and has no drain path, support material can remain trapped and obscure the optical path. Design rules for transparent PolyJet parts should include access ports, breakaway inserts, or split-section assembly for optical channels. The minimum feature size for a cleanable channel depends on water-jet nozzle geometry and support material solubility, not on layer thickness alone. A channel diameter below 2 mm should be reviewed with the machine manufacturer’s application group because cleaning reliability may become orientation-dependent. Internal surfaces that remain rough will scatter light even if the external surfaces are polished. Transparent prototype designs should therefore distinguish between sealed optical windows and channels that require support removal access.

Thermal distortion, coefficient of thermal expansion, and build chamber limits

DM_7230 belongs to the rigid transparent photopolymer class with a relatively low heat deflection temperature compared with engineering thermoplastics. Heat deflection should be evaluated by ASTM D648-18 at 0.45 MPa or 1.82 MPa, but the supplier datasheet must be consulted for the exact test stress and conditioning history. Transparent prototypes should not be placed in environments above the published heat deflection temperature for any duration if they carry a mechanical load, because creep onset and dimensional relaxation occur before large visible deformation. Coefficient of linear thermal expansion is measured by thermomechanical analysis according to ISO 11359-2; the value is relevant when a clear polycarbonate or poly(methyl methacrylate) part is being substituted for optical prototyping. The build chamber itself should be maintained within the printer’s specified operating range, which is typically narrower than the general robotics envelope. If the chamber is too hot, the jetted droplets remain fluid longer and feature edges may lose definition; if too cold, the droplets may not coalesce completely, leaving inter-droplet boundaries that scatter light.

Medical or food-contact use of DM_7230 should not be assumed from visual clarity. A transparent prototype may have no certifiable body-contact compliance unless the manufacturer has tested the polymer according to the relevant ISO 10993 series or food-contact regulation and issued a declaration of conformity. Sterilization by autoclave is generally unsuitable for low-heat-deflection photopolymers because steam temperatures exceed the thermal capability of the class and cause part distortion. Ethylene oxide or hydrogen peroxide processes may be compatible only after written confirmation from the material supplier. No statement in this section replaces the supplier safety data sheet or design-control file.

How DM_7230 differs from VeroClear, RGD720, and cast transparent polyurethane

DM_7230 is a digital material rather than a single-cartridge resin. This is the main difference from VeroClear, which is a dedicated transparent PolyJet material with a fixed formulation. A digital material can be blended from rigid and flexible base resins, so the final crosslink density and hardness may differ from both source resins. The DM_7230 designation should not be interpreted as a simple mix of two named cartridges unless the supplier has published the blend composition. Compared with RGD720, which is a semi-transparent rigid material for general-purpose models, DM_7230 is positioned for applications where internal detail visibility is required; RGD720 parts typically show a milky or amber cast unless polished. Compared with cast transparent polyurethane, DM_7230 is processed without manual mixing, degassing, or casting into molds, which reduces trapped-air porosity and short-run tooling constraints. The trade-off is that cast polyurethane can be formulated with much higher elongation at break and tougher impact response, while PolyJet photopolymers are more brittle and have lower heat deflection temperatures. The operator should not assume that a DM_7230 prototype replicates the mechanical behaviour of production polycarbonate, poly(methyl methacrylate), or silicone. It should be used for form, fit, and optical path verification only where the environmental load remains below the published limits.

Platinum-catalyzed RTV silicone moldmaking can be inhibited by residual acrylate or photoinitiator at the surface of photopolymer masters. If a DM_7230 part is used as a master for clear silicone tooling, the part should be fully post-cured, sealed with a barrier coat that is certified non-inhibiting, or subjected to a heat treatment specified by the material supplier. Condensation-cure silicones are less sensitive but may still retain surface residues. This compatibility boundary is relevant because transparent prototypes are often used to create clear silicone parts for fluidic devices; a cure inhibition failure appears as a tacky silicone interface and cannot be corrected without discarding the mold.

Lot control for DM_7230 requires recording the cartridge lot, machine material license, print mode, layer thickness, post-cure time, and support removal method. Because published data for this specific configuration is limited, a first-article qualification should include a dimensional grid, a tensile set, an optical plaque, and a thermal deflection specimen printed in the same orientation and with the same cosmetic mode as production parts. If any input changes—resin lot, printer firmware, UV lamp replacement, post-cure lamp type, or support removal station—the first-article test set should be repeated.