PU Foam FR (Flame-retardant foam)
Flame-retardant grade
Pick where fire codes apply — transport interiors, building insulation, electronics packaging.
Values for the FR condition
Other PU Foam grades and fills
PU Foam is listed in 6 conditions; see the grade overview at PU Foam.
Compare all 6 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
low-resilience memory foam (open cell) | Pick for pressure-distributing mattresses, seat pads and vibration damping where slow recovery and high hysteresis are wanted. | — | 0.09 | 120 | 5 Shore A |
FRThis page Flame-retardant foam | Pick where fire codes apply — transport interiors, building insulation, electronics packaging. | — | 0.11 | 130 | 8 Shore A |
Antistatic / conductive foam | Pick for electronics trays, IC and PCB shipping inserts needing static dissipation. | — | 0.11 | 140 | 8 Shore A |
Open CellDefault flexible open-cell slabstock/molded foam | Pick for cushioning, seating, gaskets, filtration, acoustic absorption and packaging where compliance and breathability matter. | — | 0.13 | 150 | — |
rigid closed-cell insulation / pour-in-place foam | Pick for thermal insulation panels, cold-chain, buoyancy and pour-in-place structural filling where low λ and water resistance are required. | — | 0.3 | 6 | — |
self-skinning semi-rigid molded foam | Pick for steering wheels, armrests, grips and housings needing a tough elastomeric skin over a foam core straight from the mold. | — | 4 | 120 | 55 Shore A |
What is PU Foam FR?
PU Foam FR is PU Foam in the FR grade — pick where fire codes apply — transport interiors, building insulation, electronics packaging. PU Foam FR has a tensile strength of 0.11 MPa (0.016 ksi), weaker than 99% of polymer grades. Elongation at break is 130% and the elastic modulus is 2.5×10⁻⁴ GPa (3.63×10⁻⁵ Msi). PU Foam FR has a density of 0.05 g/cm³ (0.0016 lb/in³), lighter than 90% of polymer grades. Its glass-transition temperature is -50°C (-58 °F). Open Cell is the default condition FabDigit quotes; FR is available on request or by drawing note.
Advantages
- Easy to machine — 88/100, better than 92% of polymer grades
- Lightweight — 0.05 g/cm³ (0.0016 lb/in³), better than 90% of polymer grades
- Forms and bends easily — 88/100, better than 85% of polymer grades
Limitations
- Low stiffness — 2.5×10⁻⁴ GPa (3.63×10⁻⁵ Msi), worse than 99% of polymer grades
- Hard to polish — 5/100, worse than 99% of polymer grades
- Poor heat conductor — 0.04 W/m·K (0.0214 BTU/hr·ft·°F), worse than 91% of polymer grades
- Degrades in UV without stabilisers — 25/100, worse than 76% of polymer grades
PU Foam FR properties
Typical room-temperature values for PU Foam FR; 19 are specific to this condition. Other listed values are PU Foam reference data and may not represent this condition. Bars are the position among polymer grades.
Physical3
PU Foam FR has a density of 0.05 g/cm³ (0.0016 lb/in³), lighter than 90% of polymer grades. Its glass-transition temperature is -50°C (-58 °F).
Mechanical7
PU Foam FR has a tensile strength of 0.11 MPa (0.016 ksi), weaker than 99% of polymer grades. Elongation at break is 130% and the elastic modulus is 2.5×10⁻⁴ GPa (3.63×10⁻⁵ Msi).
Thermal8
PU Foam FR is rated for continuous service to 95°C (203 °F). It conducts heat at 0.04 W/m·K (0.0214 BTU/hr·ft·°F), worse than 91% of polymer grades. Thermal expansion is 70 µm/m·K (38.9 µin/in·°F).
Electrical3
PU Foam FR has an electrical resistivity of 1×10¹⁰ Ω·m.
Chemical & Environmental2
UV resistance is poor.
Sustainability4
Producing a kilogram of PU Foam FR takes about 102 MJ of energy and emits 4.6 kg of CO₂ — less than 55% of polymer grades. Typical recycled content is 10%.
Manufacturability6
PU Foam FR's machinability is excellent (88/100, better than 92% of polymer grades); weldability poor (30/100); formability excellent (88/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with PU Foam FR
Is PU Foam easy to machine?
Cuts easily with hot wire, band knife, oscillating blade or waterjet; CNC-mill rigid and tooling grades with sharp single-flute cutters, high rpm and strong dust extraction (respirator required).
Can PU Foam be welded?
Thermoset — cannot be melt-welded; join flexible foam by flame lamination or hot-melt/PU adhesives and rigid foam by epoxy/PU adhesives.
Can PU Foam be formed, bent or molded?
Two-component reactive processing: free-rise slabstock, hot/cold-cure molding, or pour-in-place and spray application; control mold temp 35–65 °C and demold after full cream/gel/rise cycle.
What surface finishes work on PU Foam?
Open-cell surfaces cannot be polished — laminate with fabric/film or flock; rigid and tooling boards sand well and accept sealer plus PU/epoxy topcoat, and integral-skin parts are in-mold painted.
PU Foam 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 |
|---|---|---|
| TDI / MDI isocyanateTDI typical for flexible slabstock, polymeric MDI for rigid foam | 28 – 55 | 38 |
| water / blowing agentwater (CO2 generation) or HFO/HFC/pentane physical blowing agent in rigid foam | 1 – 5 | 3 |
| silicone surfactantcell regulator | 0.3 – 2 | 1 |
| amine / tin catalyst | 0.1 – 1 | 0.4 |
| flame retardantphosphate/halogen-free FR only in FR grades | 0 – 15 | 0 |
| polyether polyolpolyester polyol used for hydrolysis-sensitive/high-strength foams | ≥ 40 (balance) | — |
PU Foam FR — frequently asked
What is PU Foam FR used for?
PU Foam FR is typically used for furniture and seating cushions, mattress cores, packaging and case inserts, gasket and sealing strips, rigid insulation panels and CNC tooling board patterns and moulds. In short: cushioning open-cell foam.
What is the tensile strength of PU Foam FR?
PU Foam FR has a typical tensile strength of 0.11 MPa (0.016 ksi) — weaker than 99% of polymer grades. Strength varies by condition: see the 6 listed tempers.
Is PU Foam FR easy to machine?
Yes — machinability is rated excellent (88/100, better than 92% of polymer grades). Cuts easily with hot wire, band knife, oscillating blade or waterjet; CNC-mill rigid and tooling grades with sharp single-flute cutters, high rpm and strong dust extraction (respirator required).
Can PU Foam FR be welded?
Not readily — weldability is rated poor (30/100). Thermoset — cannot be melt-welded; join flexible foam by flame lamination or hot-melt/PU adhesives and rigid foam by epoxy/PU adhesives.
What surface finishes work on PU Foam FR?
Open-cell surfaces cannot be polished — laminate with fabric/film or flock; rigid and tooling boards sand well and accept sealer plus PU/epoxy topcoat, and integral-skin parts are in-mold painted.
Can PU Foam FR be formed, bent or molded?
Two-component reactive processing: free-rise slabstock, hot/cold-cure molding, or pour-in-place and spray application; control mold temp 35–65 °C and demold after full cream/gel/rise cycle.
What is the maximum service temperature of PU Foam FR?
PU Foam FR is rated for continuous use to about 95°C (203 °F), and briefly to 120°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in PU Foam FR?
Yes — PU Foam FR is available for injection molding; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM D3574 — Flexible Cellular Materials, Slab/Bonded/Molded Urethane Foams — ASTM (2022)
- ASTM D1622 / ASTM D1621 — Density and Compressive Properties of Rigid Cellular Plastics — ASTM (2020)
- ASTM C591 — Unfaced Preformed Rigid Cellular Polyisocyanurate Thermal Insulation — ASTM (2023)
- ASM Engineered Materials Handbook Vol.2 — Engineering Plastics — ASM International (1988)
- Cellular Solids: Structure and Properties (Gibson & Ashby) — Cambridge University Press (1997)
- Elastoflex / Elastopor rigid & flexible PU systems — BASF (2023)
- Baydur / Bayfit polyurethane system data — Covestro (2023)
- RenShape / SikaBlock PU modelling board datasheets — Sika (2023)
- CES EduPack polymer foam eco & mechanical data — Ansys Granta (2022)
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.