G9
ASTM D709
G9 is a melamine-formaldehyde glass-fabric laminate in the ASTM D709 (NEMA) grade family, pressed as sheet and rolled on mandrels as rod and tube.
Reference datasheet — G9 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
What is G9?
G9 is a melamine-formaldehyde glass-fabric laminate in the ASTM D709 (NEMA) grade family, pressed as sheet and rolled on mandrels as rod and tube. Engineers specify it where arc resistance and heat resistance dominate in electrical insulation, with tensile strength around 220 MPa in the sheet condition. The trade-offs are brittleness, moisture pickup at machined edges, very poor machinability (score 28) and limited stock in thicker sizes. Where arc resistance is less critical, G-10/FR-4 epoxy glass laminate is stronger and easier to machine; GPO-3 is the lower-cost arc barrier. G9 has a density of 1.95 g/cm³ (0.0704 lb/in³), heavier than 97% of polymer grades. G9 has a tensile strength of 220 MPa (31.9 ksi), stronger than 100% of polymer grades. Elongation at break is 1.5% and the elastic modulus is 18 GPa (2.61 Msi).
What is G9 used for?
- high-voltage terminal boards
- arc-resistant barriers
- switchgear insulation
- electrical panel components
Advantages
- Stiff — 18 GPa (2.61 Msi), better than 99% of polymer grades
- Conducts heat well — 0.35 W/m·K (0.202 BTU/hr·ft·°F), better than 91% of polymer grades
- High service temperature — 150°C (302 °F), better than 79% of polymer grades
- Good UV / weathering resistance — 55/100, better than 77% of polymer grades
Limitations
- Limited ductility — 1.5%, worse than 98% of polymer grades
- Heavy — 1.95 g/cm³ (0.0704 lb/in³), worse than 97% of polymer grades
- Difficult to machine — 28/100, worse than 90% of polymer grades
- Hard to polish — 30/100, worse than 82% of polymer grades
- Absorbs moisture — dry before molding — 0.7%, worse than 78% of polymer grades
G9 properties
Typical room-temperature values; bars are the position among polymer grades.
Physical3
G9 has a density of 1.95 g/cm³ (0.0704 lb/in³), heavier than 97% of polymer grades.
Mechanical11
G9 has a tensile strength of 220 MPa (31.9 ksi), stronger than 100% of polymer grades. Elongation at break is 1.5% and the elastic modulus is 18 GPa (2.61 Msi).
Thermal8
G9 is rated for continuous service to 150°C (302 °F). It conducts heat at 0.35 W/m·K (0.202 BTU/hr·ft·°F), better than 91% of polymer grades. Thermal expansion is 17 µm/m·K (9.44 µin/in·°F).
Electrical7
G9 is an electrical insulator with a dielectric strength of 13.8 kV/mm (350.5 V/mil) and a resistivity of 1×10¹¹ Ω·m.
Chemical & Environmental3
Corrosion resistance is very good (72/100), worse than 70% of polymer grades. UV resistance is good.
Sustainability3
Producing a kilogram of G9 takes about 72 MJ of energy and emits 4.2 kg of CO₂ — less than 93% of polymer grades. Typical recycled content is 0%.
Manufacturability2
G9's machinability is poor (28/100, worse than 90% of polymer grades).
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. G9 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with G9
Is G9 easy to machine?
Extremely abrasive — use carbide or PCD tooling, high speed / moderate feed, sharp entry to avoid delamination and dust extraction (glass + formaldehyde-cured dust).
Can G9 be welded?
Not weldable; thermoset laminate — join by bolting, riveting or epoxy bonding after abrading and solvent-cleaning the surface.
Can G9 be formed, bent or molded?
Supplied fully cured; no post-forming possible. Shapes are produced by press lamination (sheet) or rolling on mandrels (tube/rod).
G9 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 |
|---|---|---|
| melamine-formaldehyde resincured MF matrix, may contain small phenolic/alkyd modification | 30 – 42 | 36 |
| E-glass woven fabricsilane-finished glass cloth reinforcement | ≥ 58 (balance) |
What surface finishes work on G9?
Machine-finish or sand only; not paintable without primer, edges should be sealed with epoxy or varnish to limit moisture ingress and tracking.
Equivalent designations
Standards and trade names that resolve to G9 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- ASTM
- D709
How much does G9 cost?
G9 is a high-cost polymer ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
G9 — frequently asked
What is G9 used for?
G9 is typically used for high-voltage terminal boards, arc-resistant barriers, switchgear insulation and electrical panel components. In short: high arc resistance laminate; melamine heat resistance; hardest laminate to machine.
What is the tensile strength of G9?
G9 has a typical tensile strength of 220 MPa (31.9 ksi) — stronger than 100% of polymer grades.
Is G9 easy to machine?
Not especially — machinability is rated poor (28/100, worse than 90% of polymer grades). Extremely abrasive — use carbide or PCD tooling, high speed / moderate feed, sharp entry to avoid delamination and dust extraction (glass + formaldehyde-cured dust).
Can G9 be welded?
Not weldable; thermoset laminate — join by bolting, riveting or epoxy bonding after abrading and solvent-cleaning the surface.
What surface finishes work on G9?
Machine-finish or sand only; not paintable without primer, edges should be sealed with epoxy or varnish to limit moisture ingress and tracking.
Can G9 be formed, bent or molded?
Supplied fully cured; no post-forming possible. Shapes are produced by press lamination (sheet) or rolling on mandrels (tube/rod).
What is the maximum service temperature of G9?
G9 is rated for continuous use to about 150°C (302 °F), and briefly to 200°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does G9 cost?
G9 is a high-cost polymer ($$$$), pricier than about 78% 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.
Sources
- ASTM D709 — Standard Specification for Laminated Thermosetting Materials — ASTM International (2017)
- NEMA LI 1 — Industrial Laminating Thermosetting Products — NEMA (1998)
- Melamine glass industrial laminate grade G9 data — Norplex-Micarta / Franklin Fibre-Lamitex (2022)
- Engineering Plastics — Thermoset Laminates chapter — ASM International (Engineered Materials Handbook Vol. 2) (1988)
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.