Prodways PLASTCure Flex 100 is the flexible photopolymer designation within the PLASTCure 3D printing resin portfolio for vat photopolymerization platforms, specifically for low-durometer elastomer simulation. The model designation indicates a non-rigid alternative to glassy acrylate grades; its primary function is to produce parts that tolerate bending, twisting, and compression without brittle fracture. Manufacturer-published product-specific mechanical data for PLASTCure Flex 100 are limited and should be obtained from the supplier’s lot certificate before release. Characterization must be performed on printed specimens because photopolymer mechanical response is coupled to imaging dose, layer thickness, build orientation, and post-cure energy. The resin should be stored at 15–30 °C and shielded from the 370–405 nm imaging wavelengths used by DLP/LCD systems to prevent spontaneous polymerization or viscosity drift.

On MovingLight DLP equipment, the resin is recoated by a blade or wiper after each layer. Recoat behaviour is strongly influenced by viscosity; when ambient relative humidity exceeds 60%, moisture uptake increases viscosity drift and surface tack, producing recoating artefacts such as diagonal streaks or orange peel. Production lines that share vats between rigid acrylate grades and flexible grades should maintain separate vats and recoater blades to prevent cross-contamination. Cross-contamination at even small concentrations can generate anisotropic shrinkage and interlayer delamination because the two resin chemistries cure to different crosslink densities. For this reason, a dedicated resin vat, build tray, and solvent wash station are considered mandatory on multi-material manufacturing lines.

Layer thickness for elastomeric photopolymer applications is generally set between 25 µm and 100 µm. Thin layers improve through-thickness cure uniformity and isotropic elongation but increase build time and support removal burden. Supports printed from the same resin exhibit high adhesion to the part surface; contact point diameters below 0.3 mm may detach during peel, while diameters above 0.6 mm leave deep witness marks on low-durometer surfaces. Support removal in the green state is preferred because the material hardens and becomes more tear-sensitive after full post-cure.

What Process Variables Shift the Ductility Envelope?

Exposure energy per layer is the primary variable controlling the elongation-to-break and hardness balance. Underexposure produces a tacky green part with low interlayer adhesion and poor tear resistance; overexposure raises crosslink density, which increases Shore A hardness when measured in accordance with ISO 7619-1:2019 but reduces elongation at break recorded under ISO 37:2022. DLP/LCD imagers operating at 405 nm require irradiance calibration within ±5% of the manufacturer’s target across the full build area; edge-to-centre irradiance drop-off above this range can generate soft edges on large flat parts. Post-cure in a 385–405 nm flood chamber for 10–30 min at 25–40 °C is common, but thick cross-sections may require a stepwise ramp to avoid exothermic warpage. Tensile bars printed in flat orientation show different crack propagation paths than bars printed upright; comparative data are invalid unless build orientation, layer height, and post-cure protocol are listed.

Layer adhesion failure in low-durometer acrylates is often observed as non-uniform gloss or microdelamination in overhang regions. On DLP platforms with constrained surface architecture, the peel force during vat polymerization is influenced by the ratio of tensile modulus in the green state to the adhesion between cured layer and window film. When the exposure dose is insufficient, the part can separate from support tips during the peel stroke; when overexposed, the part adheres to the vat window and creates lift-off defects. Production lines commonly monitor peel-force curves from the machine’s force sensor and reject builds with a standard deviation greater than 10% across the build area. This sensor data is a more reproducible indicator of interlayer adhesion than visual inspection alone.

Green-state solvent washing introduces a temporary plasticizing effect. Solvents diffuse into the network faster than they evaporate, so as-cleaned parts can show Shore A hardness reductions and mass increases of 2–5% until conditioned. Conditioning at 23 ± 2 °C and 50 ± 5% relative humidity for a minimum of 24 h before mechanical testing is required. Enclosed cavities, microchannels, and honeycomb structures retain solvent longer because evaporation is diffusion-limited; forced-air drying should be performed at a temperature no higher than the manufacturer’s stated softening threshold. Failure to normalize solvent mass change produces artificially low hardness and artificially high elongation in acceptance tests.

When Low-Durometer Elastomer Simulation Replaces Molded Urethane

Sealing, gasketing, and vibration isolation are the most demanding functional prototyping applications. PLASTCure Flex 100 is not a direct substitute for two-part RTV silicone or injection-molded TPU in dynamic flexure or long-term sealing. Compression set remains the limiting property for sustained load; if the operating temperature is above ambient, testing should be performed according to ISO 815-1:2019 at the temperature and deflection that simulate service. Tear resistance is evaluated using ASTM D624-00(2020) Die C, but published data for this specific formulation is limited and should not be extrapolated from other flexible resins. CAD geometry should incorporate fillets and reduce sharp transitions because low-durometer parts tear from split propagation at low-energy notches. Hardness values measured by ISO 7619-1:2019 are useful for incoming lot verification but do not predict confined compression recovery or cut-growth resistance.

For functional prototypes that require repeated flexure, the relationship between build orientation and mechanical anisotropy must be characterized. Vat-photopolymerized elastomers exhibit lower strength in the build direction because molecular connectivity across layers depends on penetration cure depth. Tensile bars printed in both XY and Z orientations should be compared under ISO 37:2022; if the Z/XY strength ratio falls below 0.6, the build orientation, exposure dose, or layer height should be adjusted. Proven applications include soft-touch overmolded prototypes, dust covers, bellows for linear guides, and compression seals that are replaced after short service intervals; for applications requiring ISO 10993-5 cytotoxicity or ISO 10993-10 sensitization data, material-specific certification is necessary.

Qualification, Incoming Lot Control, and Test Standardisation

Incoming lots should be qualified by printing a standard test panel before production parts are built. The following standards are used in industrial elastomer characterization because they separate hardness, tensile, tear, and compression-set behaviour. Product-specific specification limits must be generated from supplier lot data; the table identifies the test methodology only.

Positioning Against Rigid Acrylate Resins and Molded Elastomers

PLASTCure Flex 100 differs from rigid PLASTCure acrylate resins primarily in hardness and failure mode. The Rigid 100 grade is specified for high Shore D hardness and dimensional stability in load-bearing structures, while Flex 100 is specified for low Shore A hardness and recoverable deformation under flexure. Rigid grades fail by brittle fracture and have low elongation; the flexible grade tears rather than shatters and will creep under sustained load. The comparison below is qualitative and must be confirmed with lot-specific data.

The choice between PLASTCure Flex 100 and a rigid acrylate is governed by the failure mode of the intended part. A snap-fit or load-bearing bracket should not be printed in Flex 100 because the low Shore A hardness and high elongation will not maintain dimensional tolerance under load; conversely, a rigid grade should not be used for a bellows or compression seal because it will crack at the first flexure. When comparing Flex 100 to molded TPU, layer anisotropy is the main difference: the vat-photopolymerized part has lower strength in the build direction because molecular connectivity across layers depends on penetration cure depth.

Post-cure chambers with UV LED arrays may show intensity drift over time. Irradiance should be verified with a radiometer across the 385–405 nm band before each build campaign; a drop below the target irradiance by 15% produces incomplete surface conversion and tacky surfaces even when the exposure time is fixed. Thermal post-cure ovens must not exceed the material’s deflection temperature because thin walls below 2 mm warp under convective airflow. For parts with variable wall thickness, a two-stage ramp of 10–20 min at low irradiance followed by 10–20 min at high irradiance reduces differential shrinkage.

Amine-containing additives, including some epoxy tinting pastes and anaerobic accelerators, should not be blended with PLASTCure Flex 100 because amine functionality can initiate premature crosslinking during storage and raise viscosity before printing. Material handling must follow the safety data sheet; unpolymerized resin is classified as a skin and eye irritant, and nitrile gloves are required during vat filling and part cleaning. The resin should not be discharged to drains or allowed to cure in unventilated areas. REACH and RoHS obligations are supplier-managed for the commercial formulation, but end-use certifications are outside the manufacturer’s technical datasheet. Medical device or food-contact use is not assumed and requires additional migration, cytotoxicity, and compliance testing under the relevant regional framework. Food-contact use should not be assumed absent supplier listing under 21 CFR 177.2600 or equivalent regional migration testing.

Operational boundaries are defined by green-state handling, post-cure energy, and build chamber humidity control. When relative humidity exceeds 60%, the vat cover should remain closed and active dry-air purge should be used to maintain consistent recoating. If the resin has been stored below 15 °C, it must be brought to 23 ± 2 °C and gently stirred before printing to eliminate thermal stratification. Do not use metal blades or abrasive pads to remove cured resin from the build tray because scratches create sites for low-energy tearing in flexible parts. These constraints are typical for low-durometer vat photopolymers and are part of process validation before moving from prototype to limited service production.