SMA FR (Flame-retardant compound)
Flame-retardant grade
Use where UL 94 V-0 at 1.5–3 mm is required in heat-exposed electrical housings; slight loss of impact and flow.
Values for the FR condition
Other SMA grades and fills
SMA is listed in 10 conditions; see the grade overview at SMA.
Compare all 10 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Impact-modified | Choose for automotive instrument-panel substrates and housings needing ABS-like toughness with higher heat resistance. | 36 | 36 | 25 | 105 HRR |
High-MA compatibilizer / coupling resin | Additive grade (flake/pellet/powder) used at 1–10% to compatibilize ABS/PC, PA blends and to couple glass or mineral fillers — not for standalone molding. | 42 | 42 | 1 | 87 Shore D |
Mineral / talc filled SMA | Low-warpage, low-cost stiffening for large flat panels where isotropic shrinkage beats fiber strength. | 45 | 45 | 1.5 | 87 Shore D |
FRThis page Flame-retardant compound | Use where UL 94 V-0 at 1.5–3 mm is required in heat-exposed electrical housings; slight loss of impact and flow. | 45 | 45 | 2 | 85 Shore D |
Low-MA transparent grade | Pick when optical clarity and easy flow matter more than maximum heat resistance. | 48 | 48 | 3 | 84 Shore D |
UFDefault Unfilled / Natural | Default choice for rigid, heat-resistant, dimensionally stable molded parts where impact loads are low. | 50 | 50 | 2.5 | 85 Shore D |
Heat-stabilized / high-heat molding grade | Select when HDT above ~130 °C is needed from an unreinforced styrenic, e.g. lighting bezels near lamps. | 52 | 52 | 2 | 86 Shore D |
20% glass-fiber reinforced SMA | Mid-level stiffness/heat upgrade for structural brackets and IP carriers with moderate warpage. | — | 90 | 1.8 | — |
30% glass-fiber reinforced SMA | The workhorse reinforced grade — highest stiffness/HDT combination for load-bearing heat-exposed parts. | — | 110 | 1.5 | — |
40% glass-fiber reinforced SMA | Maximum stiffness / lowest CTE version for rigid metal-replacement structures; very brittle and abrasive to tooling. | — | 125 | 1.3 | — |
What is SMA FR?
SMA FR is SMA in the FR grade — use where UL 94 V-0 at 1.5–3 mm is required in heat-exposed electrical housings; slight loss of impact and flow. SMA FR has a yield strength of 45 MPa (6.53 ksi) and a tensile strength of 45 MPa (6.53 ksi) — weaker than 58% of polymer grades. Elongation at break is 2% and the elastic modulus is 3.4 GPa (0.493 Msi). SMA FR has a density of 1.2 g/cm³ (0.0434 lb/in³), heavier than 57% of polymer grades. Its glass-transition temperature is 140°C (284 °F). UF is the default condition FabDigit quotes; FR is available on request or by drawing note.
Advantages
- Stiff — 3.4 GPa (0.493 Msi), better than 82% of polymer grades
- Low, predictable mold shrinkage — 0.45%, better than 77% of polymer grades
Limitations
- Limited ductility — 2%, worse than 95% of polymer grades
- Needs corrosion protection — 55/100, worse than 94% of polymer grades
- Degrades in UV without stabilisers — 25/100, worse than 76% of polymer grades
- Limited formability — 18/100, worse than 76% of polymer grades
SMA FR properties
Typical room-temperature values for SMA FR; 28 are specific to this condition. Other listed values are SMA reference data and may not represent this condition. Bars are the position among polymer grades.
Physical6
SMA FR has a density of 1.2 g/cm³ (0.0434 lb/in³), heavier than 57% of polymer grades. Its glass-transition temperature is 140°C (284 °F).
Mechanical17
SMA FR has a yield strength of 45 MPa (6.53 ksi) and a tensile strength of 45 MPa (6.53 ksi) — weaker than 58% of polymer grades. Elongation at break is 2% and the elastic modulus is 3.4 GPa (0.493 Msi).
Thermal11
SMA FR is rated for continuous service to 95°C (203 °F). It conducts heat at 0.19 W/m·K (0.11 BTU/hr·ft·°F), worse than 68% of polymer grades. Thermal expansion is 70 µm/m·K (38.9 µin/in·°F).
Electrical7
SMA FR is an electrical insulator with a dielectric strength of 20 kV/mm (508 V/mil) and a resistivity of 1×10¹⁴ Ω·m.
Chemical & Environmental3
Corrosion resistance is good (55/100), worse than 94% of polymer grades. UV resistance is poor.
Sustainability4
Producing a kilogram of SMA FR takes about 95 MJ of energy and emits 3.6 kg of CO₂ — less than 70% of polymer grades. Typical recycled content is 0%.
Manufacturability8
SMA FR's machinability is fair (50/100, worse than 73% of polymer grades); weldability fair (45/100); formability poor (18/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with SMA FR
Is SMA easy to machine?
Machines like SAN/PS — sharp carbide tools, high speed, light feed, air cooling; brittle so avoid sharp internal corners and pre-drill before tapping.
Can SMA be welded?
Ultrasonic, vibration and hot-plate welding work well; solvent bonding with MEK/methylene chloride blends; adhesives should be epoxy or cyanoacrylate, avoid amine-cured systems that react with anhydride.
Can SMA be formed, bent or molded?
Dry 2–4 h at 80–90 °C, mold at 230–270 °C melt / 55–90 °C tool with generous gates; keep residence time short as anhydride can hydrolyse and outgas, causing splay.
What surface finishes work on SMA?
Takes paint and hot stamping readily; can be vacuum metallized after base coat; polishes to a glossy surface but stress-cracks in aggressive solvent-based primers.
SMA 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 |
|---|---|---|
| styrenemonomer, backbone | 68 – 92 | 85 |
| maleic anhydrideMA content sets Tg/HDT and reactivity | 8 – 32 | 15 |
| butadiene/acrylic rubberonly in impact-modified terpolymer grades | 0 – 20 | 0 |
| glass fiberreinforced grades only | 0 – 40 | 0 |
SMA FR — frequently asked
What is SMA FR used for?
SMA FR is typically used for automotive interior trim, appliance housings needing higher HDT, PC/ABS compatibilizer and instrument panel components. In short: highest-HDT styrenic copolymer; PC/ABS compatibilizer resin; glass-reinforced to 40 %.
What is the yield strength of SMA FR?
SMA FR has a typical yield strength of 45 MPa (6.53 ksi) and a tensile strength of 45 MPa (6.53 ksi) — weaker than 58% of polymer grades. Strength varies by condition: see the 10 listed tempers.
Is SMA FR easy to machine?
Reasonably — machinability is rated fair (50/100, worse than 73% of polymer grades). Machines like SAN/PS — sharp carbide tools, high speed, light feed, air cooling; brittle so avoid sharp internal corners and pre-drill before tapping.
Can SMA FR be welded?
With care — weldability is rated fair (45/100). Ultrasonic, vibration and hot-plate welding work well; solvent bonding with MEK/methylene chloride blends; adhesives should be epoxy or cyanoacrylate, avoid amine-cured systems that react with anhydride.
What surface finishes work on SMA FR?
Takes paint and hot stamping readily; can be vacuum metallized after base coat; polishes to a glossy surface but stress-cracks in aggressive solvent-based primers.
Can SMA FR be formed, bent or molded?
Dry 2–4 h at 80–90 °C, mold at 230–270 °C melt / 55–90 °C tool with generous gates; keep residence time short as anhydride can hydrolyse and outgas, causing splay.
What is the maximum service temperature of SMA FR?
SMA FR is rated for continuous use to about 95°C (203 °F), and briefly to 130°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between SMA UF and SMA IM?
UF is the default condition — default choice for rigid, heat-resistant, dimensionally stable molded parts where impact loads are low. IM: choose for automotive instrument-panel substrates and housings needing ABS-like toughness with higher heat resistance. Yield strength is 50 MPa in UF versus 36 MPa in IM.
Sources
- XIRAN SMA copolymer and compound datasheets — Polyscope Polymers (2023)
- Dylark SMA resin technical data — NOVA Chemicals (2005)
- CAMPUS / UL Prospector styrenic copolymer datasets — CAMPUS Plastics (2024)
- Engineered Materials Handbook Vol. 2: Engineering Plastics — ASM International (1988)
- ISO 527 / ISO 178 / ISO 75 / ISO 306 test methods — ISO (2019)
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.