3D Systems QuickPlast Cast Urethane Material PELike 90 A is a castable polyurethane elastomer that carries a nominal durometer of 90 Shore A under ASTM D2240-15e1. The “PE-like” designation refers to a formulated surface and mechanical behavior intended to approximate the low-slip, dry-handling character of polyethylene without introducing a discrete polyolefin phase. In the QuickPlast cast urethane family, this grade is positioned for low-volume replacement of machined or molded polyolefin parts where 90 Shore A hardness supplies a balance between load-bearing resistance and recoverable deflection. The material is supplied as a two-part liquid system and is processed by gravity, vacuum, or meter-mix low-pressure casting into silicone or polyurethane tooling. It is not a thermoplastic and cannot be re-melted after cure. Because the cured network is thermoset, its dimensional stability and stress–strain behavior differ from injection-molded polyethylene in recoverable strain, thermal softening, and machining response. Published values for this specific product configuration should be obtained from the current 3D Systems material datasheet; this document describes class-level behavior, processing constraints, and comparison logic used in material selection.

Compared with direct 3D printed elastomers available from the same supplier, the cast urethane route decouples final mechanical properties from layerwise polymerization. No build orientation is present, and cured durometer is governed by chemical composition rather than UV cure depth. This orientation-independent behavior is a primary reason PELike 90 A is used in functional prototypes that must match an injection-molded polyurethane production part. A direct comparison to a specific printed elastomer requires side-by-side testing under ISO 37:2017 tensile and ISO 34-1:2022 tear methods because the stress–strain curve shape of cast urethane typically differs from that of photopolymer elastomers even when the nominal durometer is similar.

The castable chemistry in this hardness class is normally based on a polyether or polyester polyol reacted with an isocyanate-functional prepolymer, chain-extended with a short-chain diol such as 1,4-butanediol. The PE-like effect in cast urethanes is typically achieved through internal lubricant packages, surface-modifying additives, or polyether backbones that impart a dry, waxy hand feel rather than through a separate polyethylene phase; the specific additive package for PELike 90 A is not disclosed in public literature. From a processing standpoint, the two liquid components should be conditioned to 25 °C before mixing because gelation at lower temperatures can entrap air at the mold wall and shift final hardness by altering effective stoichiometry. Moisture ingress in the polyol side remains the primary kinetic boundary: water competes with the chain extender for isocyanate sites, generating carbon dioxide and yielding either microcellular texture or reduced crosslink density. A residual moisture limit of 0.05 % by weight is a typical control for unfilled cast urethane systems, though the exact acceptance criterion for this product must be taken from the manufacturer’s batch documentation.

In field use, component quality is sensitive to the age of the isocyanate component. Open containers left under high relative humidity—above 60 % RH—should be blanketed with dry nitrogen or used within a single shift; otherwise, the isocyanate can react with atmospheric water to form oligourea haze, causing variation in durometer and tear. Resin components should not be blended from containers with different lot numbers without re-testing the mix ratio, because catalyst and water content are batch-adjusted by the formulator. A production-scale failure mode reported in cast urethane operations is the use of a mixing paddle that introduces particulate contamination from release agents. Cleaning protocols must also avoid silicone- or amine-based contaminated surfaces because residual amine accelerates gelation and shifts working time unpredictably.

Why Polyethylene-Like Cast Urethane Is Specified for Low-Volume Wear Guides

In production lines, cast urethane of 90 Shore A is evaluated where HDPE or UHMWPE has historically been machined from plate stock. The PELike 90 A designation targets applications that require a non-scoring contact surface for chain guides, star wheels, conveyor rails, and sliding fixtures. The comparative advantage lies not in maximum hardness but in the combination of polyolefin-like slip and elastomeric recovery: a cast urethane part can absorb intermittent side loads and return to shape, whereas a machined HDPE wear strip may cold-flow under local stress. However, the operational temperature boundary is lower than that of unfilled HDPE. Cast urethane softens progressively above 70 °C in many formulations, and continuous-use ratings must be verified against ASTM D3045 heat-aging data rather than assumed from the hardness value alone.

Low-pressure molding with PELike 90 A requires control of four variables: mix ratio, degassing, mold temperature, and cure schedule. Because cast urethanes of this hardness are often mixed near a stoichiometric index of 1.02–1.05, off-ratio dispensing greater than ±0.5 % can shift final durometer by several Shore A points and is a common root cause of batch-to-batch variance in production cells using gear-pump meter-mix equipment. After mixing, the catalyzed material is degassed under vacuum; a typical target is -95 kPa for 2–5 min, but the specific vacuum level must avoid boiling the polyol at the chosen batch temperature. The mold should be preheated to a temperature that balances pot life and demold time. In tooling practice, 60–70 °C mold temperatures are common for high-hardness cast urethane grades, although published data for this specific configuration is limited. At higher mold temperatures, the gel time shortens and the exotherm can create internal temperatures above 100 °C in sections thicker than 20 mm, leading to discoloration or bubble formation if the mix contains residual water.

What Standards Govern Data-Sheet Comparison Across QuickPlast Cast Urethane Grades?

Comparison between PELike 90 A and other cast urethane grades should be performed through the same test method and specimen geometry; otherwise, differences in hardness, elongation, and tear can be artifacts of specimen thickness or strain rate. The following property domains are relevant for this class.

The principal difference between PELike 90 A and a conventional 90 Shore A cast urethane is the modified surface slip and wear behavior intended by the “PE-like” formulation. It is not, however, a direct chemical analogue of polyethylene: it remains an elastomeric polyurethane with higher elongation, lower stiffness, and lower melt point than HDPE or UHMWPE. When compared with softer cast urethane grades such as 55 Shore A or 70 Shore A, the 90 Shore A material transfers less strain to inserts and can sustain higher bearing stress at equal deformation, but its reduced resilience may increase impact transmission at low temperature. When compared with rigid cast urethane or epoxy tooling boards, PELike 90 A is selected where the part must survive cyclic deflection without cracking at stress concentrations. The user should not infer polyolefin chemical resistance from the PE-like designation; cast urethane is susceptible to hydrolysis in hot water and to attack by concentrated acids, alkalis, and some chlorinated solvents, whereas polyethylene is not.

If the Mold Configuration Demands Short Demold Cycles and Low Back Pressure

If the tool design includes deep ribs, encapsulated inserts, or low-pressure silicone molds, the selection of PELike 90 A should include a demolding study at the intended production temperature. Short demold cycles are possible with high catalyst activity, but the exotherm may cause premature gelation before the mold cavity has fully filled, particularly in thin sections below 3 mm. Low-viscosity fill is therefore balanced against pot life; vacuum casting in a chamber set to -90 kPa or lower can assist air evacuation from vertical ribs, but only if the material is degassed before pouring. A practical field failure observed in meter-mix cells is the accumulation of crystallized isocyanate at the static mixer element when the line is idle for more than 10 min. This changes the effective index and can produce soft, tacky surfaces at the start of the next shot. Cleaning or replacing the static mixer between production shifts is a standard control.

In packaging machinery, cast polyurethane parts with a 90 Shore A hardness are used for star wheel fingers, timing screws, and guide rails where glass or metal containers impose repetitive impact loads. The PE-like modification can reduce slip-stick behavior often observed when a standard urethane guide contacts a wet aluminum can. The part can be cut, drilled, or tapped after cure using carbide tooling, but the machined surface may lose the low-friction skin created against a polished mold. For food-contact subcomponents, compliance with EU 10/2011 or FDA 21 CFR 177.2600 must be confirmed for the cured formulation, not assumed from the base resin type. Repeated washing with caustic solutions above 60 °C can hydrolyze an ester-based backbone if a polyester polyol is used; the material supplier should provide immersion test data under ASTM D471-16a for the exact sanitizer chemistry.

Cure-Schedule Boundaries and Shrinkage Control in Low-Pressure Molding

Dimensional control for PELike 90 A is governed by liquid-to-solid shrinkage, thermal expansion differences, and post-cure rearrangement. Shrinkage in cast urethanes is anisotropic and is influenced by mold wall adhesion; typical values for unfilled Shore A 90 systems are reported between 0.5 % and 1.5 % linear, but product-specific shrinkage for this grade is limited to the manufacturer’s tooling documentation. Tooling compensation should be derived from measurements on a geometrically representative trial casting, not from a single data-sheet coefficient. Post-cure at 80 °C for 16 h is common in cast urethane processing to force completion of the isocyanate reaction; the exact schedule for PELike 90 A must be followed to avoid incomplete cure that manifests as high compression set and surface tack. The material should not be exposed to alcohol, strong base, or steam above its service temperature without an immersion test, because such exposure can plasticize or degrade the cured network.