PU Foam
PU Foam is cellular polyurethane made by reacting polyol and isocyanate with a blowing agent, covering soft open-cell flexible foam, closed-cell, viscoelastic, integral-skin, flame-retardant, ESD and rigid tooling-board grades.
Values for the Open Cell condition
PU Foam grades and fills
PU Foam is supplied in 6 conditions, soft to hard. Open Cell is the default FabDigit quotes; the values on this page are for it.
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 | |
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 |
Supply forms, finishes and certifications
Ways PU Foam is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
Tooling Board | High-density rigid PU modelling/tooling board | Supply form |
What is PU Foam?
PU Foam is cellular polyurethane made by reacting polyol and isocyanate with a blowing agent, covering soft open-cell flexible foam, closed-cell, viscoelastic, integral-skin, flame-retardant, ESD and rigid tooling-board grades. The default flexible grade is about 33 kg/m³ with 0.13 MPa tensile strength, 150 % elongation and 0.038 W/m·K conductivity, so it serves cushioning, sealing, packaging and insulation, while rigid boards machine easily for models and moulds. Service is limited to roughly 90 °C, unprotected foam yellows and degrades under UV, and open-cell grades take up water; closed-cell EPP is the alternative where repeated impact recovery is required. PU Foam has a density of 0.03 g/cm³ (0.0012 lb/in³), lighter than 92% of polymer grades. Its glass-transition temperature is -50°C (-58 °F). PU Foam has a tensile strength of 0.13 MPa (0.0189 ksi), weaker than 98% of polymer grades. Elongation at break is 150% and the elastic modulus is 2×10⁻⁴ GPa (2.9×10⁻⁵ Msi).
What is PU Foam used for?
- Furniture and seating cushions
- Mattress cores
- Packaging and case inserts
- Gasket and sealing strips
- Rigid insulation panels
- CNC tooling board patterns and moulds
- Automotive NVH and headliner pads
- Integral-skin armrests and grips
Advantages
- Easy to machine — 90/100, better than 95% of polymer grades
- Lightweight — 0.03 g/cm³ (0.0012 lb/in³), better than 92% of polymer grades
- Forms and bends easily — 90/100, better than 91% of polymer grades
Limitations
- Low stiffness — 2×10⁻⁴ GPa (2.9×10⁻⁵ 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 (0.022 BTU/hr·ft·°F), worse than 90% of polymer grades
- Degrades in UV without stabilisers — 25/100, worse than 76% of polymer grades
PU Foam properties
Typical room-temperature values for PU Foam-Open Cell; bars are the position among polymer grades.
Physical3
PU Foam has a density of 0.03 g/cm³ (0.0012 lb/in³), lighter than 92% of polymer grades. Its glass-transition temperature is -50°C (-58 °F).
Mechanical7
PU Foam has a tensile strength of 0.13 MPa (0.0189 ksi), weaker than 98% of polymer grades. Elongation at break is 150% and the elastic modulus is 2×10⁻⁴ GPa (2.9×10⁻⁵ Msi).
Thermal8
PU Foam is rated for continuous service to 90°C (194 °F). It conducts heat at 0.04 W/m·K (0.022 BTU/hr·ft·°F), worse than 90% of polymer grades. Thermal expansion is 70 µm/m·K (38.9 µin/in·°F).
Electrical3
PU Foam has an electrical resistivity of 1×10¹⁰ Ω·m.
Chemical & Environmental2
UV resistance is poor.
Sustainability4
Producing a kilogram of PU Foam 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's machinability is excellent (90/100, better than 95% of polymer grades); weldability poor (30/100); formability excellent (90/100).
Common Calculations4
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the polymer family
Yield strength against density for every polymer grade FabDigit runs. PU Foam is highlighted; hover a dot for its name, or open the interactive family chart.
Working with PU Foam
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.
Manufacturability
The process limits FabDigit applies to PU Foam. Every PU Foam part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
Injection molding
| Mold shrinkage | — |
|---|---|
| Wall thickness | — – — |
| Recommended draft | — |
| Pre-drying | — |
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) |
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.
Surface treatments FabDigit runs on polymer parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Injection Molding Coating
Metallization / Functional
Equivalent designations
Standards and trade names that resolve to PU Foam in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Also called
- Polyurethane Foam
How much does PU Foam cost?
PU Foam is a budget-cost polymer ($), cheaper than about 82% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
PU Foam — frequently asked
What is PU Foam used for?
PU Foam is typically used for furniture and seating cushions, mattress cores, packaging and case inserts, gasket and sealing strips, rigid insulation panels and CNC tooling board patterns and moulds. In short: cushioning open-cell foam.
What is the tensile strength of PU Foam?
PU Foam has a typical tensile strength of 0.13 MPa (0.0189 ksi) — weaker than 98% of polymer grades. Strength varies by condition: see the 6 listed tempers.
Is PU Foam easy to machine?
Yes — machinability is rated excellent (90/100, better than 95% of polymer grades). Cuts easily with hot wire, band knife, oscillating blade or waterjet; CNC-mill rigid and tooling grades with sharp single-flute cutters, high rpm and strong dust extraction (respirator required).
Can PU Foam be welded?
Not readily — weldability is rated poor (30/100). Thermoset — cannot be melt-welded; join flexible foam by flame lamination or hot-melt/PU adhesives and rigid foam by epoxy/PU adhesives.
What surface finishes work on PU Foam?
Open-cell surfaces cannot be polished — laminate with fabric/film or flock; rigid and tooling boards sand well and accept sealer plus PU/epoxy topcoat, and integral-skin parts are in-mold painted.
Can PU Foam be formed, bent or molded?
Two-component reactive processing: free-rise slabstock, hot/cold-cure molding, or pour-in-place and spray application; control mold temp 35–65 °C and demold after full cream/gel/rise cycle.
What is the maximum service temperature of PU Foam?
PU Foam is rated for continuous use to about 90°C (194 °F), and briefly to 120°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does PU Foam cost?
PU Foam is a budget-cost polymer ($), cheaper than about 82% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Can FabDigit make parts in PU Foam?
Yes — PU Foam 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; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.