PU-Foam-Rigid FR (Flame-retardant rigid foam)
Flame-retardant grade
Use for rail, aircraft-interior or enclosure mockups where a flammability rating is contractually required.
Values for the FR condition
Other PU-Foam-Rigid grades and fills
PU-Foam-Rigid is listed in 7 conditions; see the grade overview at PU-Foam-Rigid.
Compare all 7 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Low-density rigid foam, ~0.15 g/cm³ | Pick when minimum weight or maximum fill volume matters and loads are essentially self-weight only (display models, void filling, insulating cores). | — | 2 | 3 | 30 Shore D |
FRThis page Flame-retardant rigid foam | Use for rail, aircraft-interior or enclosure mockups where a flammability rating is contractually required. | — | 6 | 3 | 48 Shore D |
D030Default Standard rigid casting foam, ~0.30 g/cm³ | Default choice for lightweight mockups and large-volume parts where handling stiffness and machinability must both be adequate. | — | 6 | 4 | 45 Shore D |
Self-skinning (integral-skin) rigid foam | Select when the as-cast surface must be paint-ready without extensive filling — dense skin over a light foam core. | — | 8 | 5 | 55 Shore D |
Medium-high density rigid foam, ~0.50 g/cm³ | Use where the foam must take screws, inserts or fixture clamping and still be milled cleanly. | — | 12 | 5 | 58 Shore D |
Dense structural / tooling foam, ~0.70 g/cm³ | Choose for machinable model-board-like blocks, load-bearing inserts and pattern work where near-solid stiffness is needed. | — | 18 | 6 | 68 Shore D |
Mineral/glass-filled dense rigid foam | Choose for dimensionally stable pattern, jig and low-run mould blocks needing lower CTE and higher stiffness than neat foam. | — | 20 | 2 | 78 Shore D |
What is PU-Foam-Rigid FR?
PU-Foam-Rigid FR is PU-Foam-Rigid in the FR grade — use for rail, aircraft-interior or enclosure mockups where a flammability rating is contractually required. PU-Foam-Rigid FR has a tensile strength of 6 MPa (0.798 ksi), weaker than 90% of polyurethane grades. Elongation at break is 3% and the elastic modulus is 0.22 GPa (0.0319 Msi). PU-Foam-Rigid FR has a density of 0.35 g/cm³ (0.0126 lb/in³), lighter than 95% of polyurethane grades. Its glass-transition temperature is 95°C (203 °F). D030 is the default condition FabDigit quotes; FR is available on request or by drawing note.
Advantages
- Lightweight — 0.35 g/cm³ (0.0126 lb/in³), better than 95% of polyurethane grades
- Easy to machine — 84/100, better than 95% of polyurethane grades
Limitations
- Hard to polish — 20/100, worse than 97% of polyurethane grades
- Limited ductility — 3%, worse than 95% of polyurethane grades
- Poor heat conductor — 0.08 W/m·K (0.0451 BTU/hr·ft·°F), worse than 90% of polyurethane grades
- Absorbs moisture — dry before molding — 0.8%, worse than 88% of polyurethane grades
PU-Foam-Rigid FR properties
Typical room-temperature values for PU-Foam-Rigid FR; 22 are specific to this condition. Other listed values are PU-Foam-Rigid reference data and may not represent this condition. Bars are the position among polyurethane grades.
Physical4
PU-Foam-Rigid FR has a density of 0.35 g/cm³ (0.0126 lb/in³), lighter than 95% of polyurethane grades. Its glass-transition temperature is 95°C (203 °F).
Mechanical11
PU-Foam-Rigid FR has a tensile strength of 6 MPa (0.798 ksi), weaker than 90% of polyurethane grades. Elongation at break is 3% and the elastic modulus is 0.22 GPa (0.0319 Msi).
Thermal10
PU-Foam-Rigid FR is rated for continuous service to 85°C (185 °F). It conducts heat at 0.08 W/m·K (0.0451 BTU/hr·ft·°F), worse than 90% of polyurethane grades. Thermal expansion is 70 µm/m·K (38.9 µin/in·°F).
Electrical4
PU-Foam-Rigid FR has an electrical resistivity of 1×10¹¹ Ω·m.
Chemical & Environmental2
UV resistance is poor.
Sustainability4
Producing a kilogram of PU-Foam-Rigid FR takes about 103 MJ of energy and emits 4.6 kg of CO₂ — less than 62% of polyurethane grades. Typical recycled content is 0%.
Manufacturability5
PU-Foam-Rigid FR's machinability is very good (84/100, better than 95% of polyurethane grades); formability not recommended (4/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with PU-Foam-Rigid FR
Is PU-Foam-Rigid easy to machine?
Cuts and mills very easily with sharp single-flute or foam-specific tooling at high rpm/low feed; use vacuum extraction — the dust is fine and irritant — and expect cell tear-out on thin edges of low-density grades.
Can PU-Foam-Rigid be welded?
Thermoset and cellular: not weldable; join with PU/epoxy adhesives, dowels or embedded inserts potted in place.
Can PU-Foam-Rigid be formed, bent or molded?
Two-component pour under vacuum into silicone or epoxy tools at 25–40 °C mould temperature; meter accurately, degas, and control shot weight/vent layout since density and skin quality depend on constrained rise (demould typically 20–60 min).
What surface finishes work on PU-Foam-Rigid?
Skin sands well but the open core must be sealed with polyester filler or a 2K PU primer before painting; no plating, and UV exposure needs a pigmented/clear-coated topcoat to prevent yellowing.
PU-Foam-Rigid chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| polymeric MDI (diphenylmethane diisocyanisocyanate side | 40 – 60 | 50 |
| blowing agent (water / HFO / pentane)defines cell structure and density | 0.5 – 4 | 2 |
| amine + tin catalyst package | 0.3 – 2 | 1 |
| mineral / glass filler (filled grades on0 in the default unfilled foam | 0 – 40 | 0 |
| flame retardant (phosphate ester, FR gra | 0 – 15 | 0 |
| polyether/polyester polyol blend — compocontains catalysts, silicone surfactant, chain extenders | ≥ 35 (balance) | — |
PU-Foam-Rigid FR — frequently asked
What is PU-Foam-Rigid FR used for?
PU-Foam-Rigid FR is typically used for lightweight mockups, core/filler inserts, insulation prototypes and design models. In short: lightest vacuum-cast PU; self-skinning foam system; very easy to machine.
What is the tensile strength of PU-Foam-Rigid FR?
PU-Foam-Rigid FR has a typical tensile strength of 6 MPa (0.798 ksi) — weaker than 90% of polyurethane grades. Strength varies by condition: see the 7 listed tempers.
Is PU-Foam-Rigid FR easy to machine?
Yes — machinability is rated very good (84/100, better than 95% of polyurethane grades). Cuts and mills very easily with sharp single-flute or foam-specific tooling at high rpm/low feed; use vacuum extraction — the dust is fine and irritant — and expect cell tear-out on thin edges of low-density grades.
Can PU-Foam-Rigid FR be welded?
Thermoset and cellular: not weldable; join with PU/epoxy adhesives, dowels or embedded inserts potted in place.
What surface finishes work on PU-Foam-Rigid FR?
Skin sands well but the open core must be sealed with polyester filler or a 2K PU primer before painting; no plating, and UV exposure needs a pigmented/clear-coated topcoat to prevent yellowing.
Can PU-Foam-Rigid FR be formed, bent or molded?
Two-component pour under vacuum into silicone or epoxy tools at 25–40 °C mould temperature; meter accurately, degas, and control shot weight/vent layout since density and skin quality depend on constrained rise (demould typically 20–60 min).
What is the maximum service temperature of PU-Foam-Rigid FR?
PU-Foam-Rigid FR is rated for continuous use to about 85°C (185 °F), and briefly to 120°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- F-series rigid casting foams (technical data sheets) — Axson Technologies / Sika Advanced Resins (2022)
- FOAM-iT! rigid urethane foam series — Smooth-On (2023)
- ISO 844 — Rigid cellular plastics, compression test — ISO (2021)
- ASTM D1622 / D1623 — Apparent density and tensile properties of rigid cellular plastics — ASTM (2020)
- Polyurethanes Handbook (Oertel), rigid foam property–density relations — Hanser (1994)
- Cellular polymer property tables (rigid PU) — CAMPUS / Ashby CES material data (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.