Poron · grade
Poron Firm
Properties of the Firm condition, compared with the other Poron grades.
Pick when the pad must carry higher load or resist thinning under sustained clamp force, e.g. structural standoff and vibration pads.
What is Poron Firm?
Poron Firm is Poron in the Firm grade — pick when the pad must carry higher load or resist thinning under sustained clamp force, e.g. structural standoff and vibration pads. Poron Firm has a tensile strength of 2 MPa (0.232 ksi), weaker than 84% of polymer grades. Elongation at break is 140% and the elastic modulus is 0 GPa (2.18×10⁻⁴ Msi). Poron Firm has a density of 0.48 g/cm³ (0.0173 lb/in³), lighter than 83% of polymer grades. Its glass-transition temperature is -35°C (-31 °F). Standard is the default condition FabDigit quotes; Firm is available on request or by drawing note.
Advantages
- Forms and bends easily — 90/100, better than 92% of polymer grades
- Lightweight — 0.48 g/cm³ (0.0173 lb/in³), better than 83% of polymer grades
- Easy to machine — 80/100, better than 83% of polymer grades
Limitations
- Absorbs moisture — dry before molding — 3%, worse than 99% of polymer grades
- Low stiffness — 0 GPa (2.18×10⁻⁴ Msi), worse than 97% of polymer grades
- Poor heat conductor — 0.07 W/m·K (0.0404 BTU/hr·ft·°F), worse than 83% of polymer grades
- Needs corrosion protection — 70/100, worse than 80% of polymer grades
Poron Firm properties
Typical room-temperature values for Poron Firm — 8 properties are specific to this condition; the rest are grade-level values shared by every Poron grade. Each bar shows where the value sits among the polymer grades in FabDigit's library — further right is higher.
Physical3
Poron Firm has a density of 0.48 g/cm³ (0.0173 lb/in³), lighter than 83% of polymer grades. Its glass-transition temperature is -35°C (-31 °F).
Mechanical9
Poron Firm has a tensile strength of 2 MPa (0.232 ksi), weaker than 84% of polymer grades. Elongation at break is 140% and the elastic modulus is 0 GPa (2.18×10⁻⁴ Msi).
Thermal6
Poron Firm is rated for continuous service to 90°C (194 °F). It conducts heat at 0.07 W/m·K (0.0404 BTU/hr·ft·°F), worse than 83% of polymer grades.
Electrical2
Chemical & Environmental3
Corrosion resistance is very good (70/100), worse than 80% of polymer grades. UV resistance is fair.
Sustainability3
Producing a kilogram of Poron Firm takes about 100 MJ of energy and emits 5 kg of CO₂ — less than 61% of polymer grades. Typical recycled content is 0%.
Manufacturability2
Poron Firm's machinability is very good (80/100, better than 83% of polymer grades); formability excellent (90/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other Poron grades and fills
Poron is also supplied in 7 other conditions. The full side-by-side table is on the Poron overview.
- StandardDefaultDefault choice for gasket sealing, screen and battery cushioning where low closure force and high conformability matter.1 MPa tensile
- FirmPick when the pad must carry higher load or resist thinning under sustained clamp force, e.g. structural standoff and vibration pads.2 MPa tensile
Working with Poron Firm
Is Poron easy to machine?
Convert by steel-rule die, rotary kiss-cut, laser (with fume extraction) or waterjet; avoid conventional milling — the foam tears and compresses under tool load.
Can Poron be welded?
Not weldable; join with acrylic PSA transfer tape, urethane adhesive or mechanical capture in a housing groove.
Can Poron be formed, bent or molded?
Supplied as cast/skived sheet and roll; forms only by compression in the assembly — design for 20–50 % working deflection and avoid >70 % compression to preserve recovery.
What surface finishes work on Poron?
No coating needed; surfaces are as-skived or film/PSA laminated, and can be printed or laminated with PET/PI films for low-friction or shielding layers.
Poron 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 |
|---|---|---|
| polyester/polyether polyolsoft-segment backbone; ether-type used for hydrolysis-resistant grades | 50 – 70 | 60 |
| diisocyanate (MDI/TDI)hard-segment / crosslinker | 20 – 40 | 30 |
| cell-control additives, surfactants, pigmicrocellular structure control | 2 – 10 | 5 |
| flame retardant (FR grades only)present only in UL 94 V-0 variants | 0 – 15 | 8 |
Poron Firm — frequently asked
What is Poron Firm used for?
Poron Firm is typically used for electronic enclosure sealing gaskets, vibration and shock dampers, display and touchscreen cushions, wearable device skin-contact padding, impact padding in protective gear and battery pack compression pads. In short: cushioning microcellular urethane.
What is the tensile strength of Poron Firm?
Poron Firm has a typical tensile strength of 2 MPa (0.232 ksi) — weaker than 84% of polymer grades. Strength varies by condition: see the 8 listed tempers.
Is Poron Firm easy to machine?
Yes — machinability is rated very good (80/100, better than 83% of polymer grades). Convert by steel-rule die, rotary kiss-cut, laser (with fume extraction) or waterjet; avoid conventional milling — the foam tears and compresses under tool load.
Can Poron Firm be welded?
Not weldable; join with acrylic PSA transfer tape, urethane adhesive or mechanical capture in a housing groove.
What surface finishes work on Poron Firm?
No coating needed; surfaces are as-skived or film/PSA laminated, and can be printed or laminated with PET/PI films for low-friction or shielding layers.
Can Poron Firm be formed, bent or molded?
Supplied as cast/skived sheet and roll; forms only by compression in the assembly — design for 20–50 % working deflection and avoid >70 % compression to preserve recovery.
What is the maximum service temperature of Poron Firm?
Poron Firm 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.
Can FabDigit make parts in Poron Firm?
Yes — Poron Firm is available for sheet metal and injection molding with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- PORON Microcellular Urethane Product Data (4701 / 4790 series, AquaPro, XRD) — Rogers Corporation (2023)
- ASTM D1056 — Flexible Cellular Materials, Sponge or Expanded Rubber — ASTM (2020)
- ASTM D3574 — Flexible Cellular Materials, Slab, Bonded and Molded Urethane Foams — ASTM (2017)
- UL 94 — Tests for Flammability of Plastic Materials — UL (2020)
- Polyurethane Handbook (structure–property data for microcellular elastomers) — Hanser (1994)
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.