Carbon Printers UMA 90 Urethane Methacrylate is a single-component, light-curable urethane methacrylate photopolymer developed for Digital Light Synthesis production platforms. The model designation UMA 90 identifies a crosslinked urethane methacrylate network with a nominal cured hardness of 90 Shore A when measured under ASTM D2240-15e1; the methacrylate backbone separates it from epoxy, cyanate ester, and silicone resins qualified for the same equipment family. The liquid resin is supplied in machine-readable cartridges that lock exposure dose, build speed, and thermal cure recipe to the specific grade. In cured form, Carbon Printers UMA 90 Urethane Methacrylate parts exhibit elastomeric recovery, higher durometer than flexible urethane grades such as FPU 50, and tear resistance that permits thinner functional walls in cyclic-loading prototypes. The grade is used for functional prototypes and short production runs where molded TPU geometry would require tooling investment; published data for this specific configuration is limited outside the manufacturer’s controlled test environment.

What Engineering Data Are Reported for UMA 90?

Manufacturer-published data for Carbon Printers UMA 90 Urethane Methacrylate are generated from specimens printed in the XY plane and conditioned for 48 h at 23 °C and 50% RH unless otherwise noted. The values in Table 1 are reproduced as ranges; they are not independent laboratory data and should not be treated as design allowables without additional testing. Photopolymerized elastomers show orientation-dependent tensile properties, and the difference between XY and Z elongation is greater than the difference in durometer. Tensile specimens follow ASTM D638-14 Type IV because the material is elastomeric but stiff enough to permit rigid specimen geometry; tear specimens follow ASTM D624-00(2012) Die C. Compression set values are determined on cylindrical buttons with 25% deflection and are strongly affected by oven cure completeness.

Batch release testing for Carbon Printers UMA 90 Urethane Methacrylate includes methacrylate unsaturation verification by Fourier-transform infrared spectroscopy and liquid viscosity measurement under ASTM D2196-20. Liquid density under ASTM D1475-13 is used as a secondary lot-release check; cured density under ASTM D792-20 is not a sensitive degree-of-cure indicator and is used mainly for material identity. Incoming resin viscosity drift outside the 2,800–3,500 mPa·s band can indicate moisture ingress or partial thermal polymerization during shipping. Containers exposed to production rooms above 60% RH should remain sealed and blanketed with dry nitrogen during dispensing. Because the uncured methacrylate contains reactive diluents, handling requires nitrile gloves and eye protection; spills are absorbed, cured with ultraviolet light, and disposed as polymer waste.

Kinetic and Rheological Boundaries That Restrict DLS Processing

Processing of Carbon Printers UMA 90 Urethane Methacrylate on DLS equipment is restricted to machine-controlled recipes loaded from the resin cartridge data. Manual modification of optical dose, dead-zone thickness, or build speed is not supported because methacrylate conversion and oxygen inhibition at the continuously renewable window interface depend on oxygen partial pressure, projector irradiance stability, and resin temperature. The oxygen-permeable membrane must be inspected for scratches and permeability drift; a degraded window increases oxygen flux at the build interface and reduces surface conversion. These effects are not unique to UMA 90, but the higher crosslink density of the methacrylate network makes the material more sensitive to undercure at the part surface than softer urethane grades.

On the production floor, the resin cartridge should be brought to 20–25 °C before printing. Cold resin increases the oxygen-inhibited layer thickness and can require longer exposure; warm resin can reduce conversion and leave tacky parts. Projector irradiance is measured at the window plane with a radiometer calibrated to the manufacturer’s specified wavelength; an irradiance drift of 5% from baseline is sufficient to shift cured film thickness and alter hole diameter or snap-fit beam thickness. Parts exiting the printer retain partially reacted surface monomer and are processed through a two-stage solvent wash followed by a forced-air oven with ±5 °C uniformity across the working volume. Dense oven loading can extend the time required for the part core to reach prescribed cure temperature, and that delay produces higher compression set and lower tear strength in thick sections. Insufficient thermal cure leaves latent surface methacrylate and can raise compression set; excessive cure can darken thin sections and embrittle small features.

During long production runs, build platforms and window surfaces are cleaned and inspected between builds because crystallized methacrylate particulate can scratch the oxygen-permeable window. The wash and cure recipe for UMA 90 is distinct from the recipes for rigid grades; substituting the RPU 70 solvent may cause surface tack or swelling. Batch records should include resin lot number, wash solvent exchange count, oven load density, and printed test coupon hardness at build start and finish.

Hardness and Crosslink Density Relative to Carbon's Polyurethane Resins

Carbon Printers UMA 90 Urethane Methacrylate is positioned between the flexible polyurethane and rigid polyurethane resins in the Carbon portfolio. At 90 Shore A it is harder than EPU 40 at 40 Shore A and FPU 50 at 50 Shore A, but it does not approach the flexural modulus of RPU 70 at 70 Shore D. The methacrylate functionality increases crosslink density relative to linear polyol-based urethane networks, which raises hardness and tear strength while reducing ultimate elongation. Compared with EPX 82 epoxy and CE 221 cyanate ester, UMA 90 has lower heat deflection and lower solvent resistance but greater strain capacity. Table 2 summarizes the cross-portfolio differences using manufacturer-published ranges.

The comparison shows that Carbon Printers UMA 90 Urethane Methacrylate is not a direct replacement for stiff structural grades such as RPU 70 or high-temperature resins such as CE 221. Its performance envelope lies in abrasion-resistant elastomer components where a 90 Shore A durometer reduces part distortion under load but still permits snap-fit assembly and repeated flexing. This is a practical distinction from lower-durometer elastomers, which may produce lower insertion force but exhibit greater wall deflection and lower fastener retention.

Carbon Printers UMA 90 Urethane Methacrylate is specified for snap-fit enclosure ribs, cable clips, belt segments, brackets, and protective equipment edges where molded TPU would require tooling. The higher durometer allows smaller negative features and better shape retention than softer elastomers, but snap-fit designs should be validated with repeated insertion cycling at the target environmental temperature rather than by static tensile data alone. For lattice structures such as padding and footwear midsole prototypes, UMA 90 has been evaluated as a high-durometer lattice resin; published data for this specific configuration is limited, and node-level strain concentration makes compression set testing under ASTM D395-18 Method B a mandatory qualification step. Production-scale builds on large-format DLS systems have shown that thick solid cross-sections can retain a hardness gradient through the part wall if the thermal cure does not drive the core to the resin-specific dwell temperature for the full recipe duration.

When dimensional accuracy is required, measurements should be performed after conditioning to equilibrium because the cured polymer absorbs atmospheric moisture. Water absorption can be characterized by ASTM D570-98(2018); the resulting mass change may be sufficient to alter interference fits on parts with tight clearance. Dynamic mechanical analysis under ASTM D4065-20 from −40 °C to 100 °C at 1 Hz is used to locate softening behavior and confirm batch-to-batch consistency. Creep and stress-relaxation data should be generated according to ASTM D2990-17 if the part is continuously loaded; published data for this specific configuration is limited.

When UMA 90 Replaces Molded TPU in Functional Prototyping

When Carbon Printers UMA 90 Urethane Methacrylate is substituted for injection-molded TPU in field-test parts, the qualification path must account for thermoset behavior. The material is not melt-processable and cannot be reground and remolded as thermoplastic urethane. Chemical compatibility is screened under ASTM D543-14; the cured network resists aliphatic hydrocarbon contact but may soften or swell in ketones, esters, and aromatic solvents. The resin should not be mixed with primary-amine-containing additives or uncured epoxy hardeners because amine-methacrylate reactions can generate uncontrolled premature crosslinking and local exotherms. If outdoor exposure is planned, accelerated weathering under ASTM G154-16 Cycle A should be conducted; an aliphatic clearcoat or ultraviolet absorber may be required to prevent surface chalking and gloss loss.

Food-contact, medical, or cosmetic applications are not automatically supported by the base resin grade; users must verify specific regulatory status for the batch under applicable regulations, including REACH and RoHS and, where relevant, FDA 21 CFR sections. Waste solvent containing uncured resin is managed under local photopolymer waste regulations; cured polymer is disposed as non-hazardous solid waste only after verification against local requirements. Final acceptance testing should include hardness coupons at build start and finish, a dimensional artifact measured on a calibrated coordinate-measuring machine, and tensile tear specimens from each build lot. Parts that fail the compression set requirement after thermal cure should be quarantined and the oven load density, airflow configuration, and dwell time reviewed before additional processing.