G5 · grade
G5-G9
Properties of the G9 condition, compared with the other G5 grades.
Pick G9 over G5 when the part must hold dielectric strength and insulation resistance after humidity exposure while keeping melamine's arc/tracking resistance.
What is G5-G9?
G5-G9 is G5 in the G9 grade — pick G9 over G5 when the part must hold dielectric strength and insulation resistance after humidity exposure while keeping melamine's arc/tracking resistance. G5-G9 has a tensile strength of 240 MPa (34.8 ksi), weaker than 55% of composite grades. Elongation at break is 1.5% and the elastic modulus is 17 GPa (2.47 Msi). G5-G9 has a density of 1.95 g/cm³ (0.0704 lb/in³), heavier than 74% of composite grades. Melamine Matrix is the default condition FabDigit quotes; G9 is available on request or by drawing note.
Advantages
- Low embodied carbon — 4.5 kg CO₂/kg, better than 79% of composite grades
Limitations
- Needs corrosion protection — 58/100, worse than 82% of composite grades
G5-G9 properties
Typical room-temperature values for G5-G9 — 8 properties are specific to this condition; the rest are grade-level values shared by every G5 grade. Each bar shows where the value sits among the composite grades in FabDigit's library — further right is higher.
Physical3
G5-G9 has a density of 1.95 g/cm³ (0.0704 lb/in³), heavier than 74% of composite grades.
Mechanical12
G5-G9 has a tensile strength of 240 MPa (34.8 ksi), weaker than 55% of composite grades. Elongation at break is 1.5% and the elastic modulus is 17 GPa (2.47 Msi).
Thermal8
G5-G9 is rated for continuous service to 155°C (311 °F). It conducts heat at 0.35 W/m·K (0.202 BTU/hr·ft·°F), better than 50% of composite grades. Thermal expansion is 14 µm/m·K (7.78 µin/in·°F).
Electrical7
G5-G9 is an electrical insulator with a dielectric strength of 16 kV/mm (406.4 V/mil) and a resistivity of 1×10¹¹ Ω·m.
Chemical & Environmental3
Corrosion resistance is good (58/100), worse than 82% of composite grades. UV resistance is fair.
Sustainability3
Producing a kilogram of G5-G9 takes about 75 MJ of energy and emits 4.5 kg of CO₂ — less than 91% of composite grades. Typical recycled content is 0%.
Manufacturability2
G5-G9's machinability is poor (25/100, worse than 65% of composite grades).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other G5 grades and fills
G5 is also supplied in 1 other condition. The full side-by-side table is on the G5 overview.
- Melamine MatrixDefaultStandard choice when arc resistance, tracking resistance and inherent flame retardance matter more than humid-state electrical stability.220 MPa tensile
- G9Pick G9 over G5 when the part must hold dielectric strength and insulation resistance after humidity exposure while keeping melamine's arc/tracking resistance.240 MPa tensile
Working with G5-G9
Is G5 easy to machine?
Machine dry with sharp carbide or diamond tooling, high speed / moderate feed, backing plate to avoid edge chipping and delamination; provide dust extraction (glass + melamine dust is irritant).
Can G5 be welded?
Not weldable — thermoset laminate; join by bolting, riveting or epoxy bonding after abrading and solvent-cleaning the surface.
Can G5 be formed, bent or molded?
Supplied as fully cured flat sheet, rod or tube; no post-forming possible, all geometry by machining, punching (thin sheet, warm) or waterjet.
What surface finishes work on G5?
Edges should be deburred and sealed with varnish or epoxy to limit moisture pickup; can be sanded but not polished to gloss; paint only over abraded, dry surfaces.
G5 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 |
|---|---|---|
| E-glass woven fabricreinforcement, plain/twill weave cloth | 50 – 65 | 58 |
| melamine-formaldehyde resinmatrix; may be modified with phenolic for toughness | ≥ 35 (balance) | — |
G5-G9 — frequently asked
What is G5-G9 used for?
G5-G9 is typically used for arc barriers, switchgear insulators, terminal blocks and boards, punched washers and spacers, contactor and circuit breaker components and bus bar supports. In short: melamine arc-resistant laminate.
What is the tensile strength of G5-G9?
G5-G9 has a typical tensile strength of 240 MPa (34.8 ksi) — weaker than 55% of composite grades. Strength varies by condition: see the 2 listed tempers.
Is G5-G9 easy to machine?
Not especially — machinability is rated poor (25/100, worse than 65% of composite grades). Machine dry with sharp carbide or diamond tooling, high speed / moderate feed, backing plate to avoid edge chipping and delamination; provide dust extraction (glass + melamine dust is irritant).
Can G5-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 G5-G9?
Edges should be deburred and sealed with varnish or epoxy to limit moisture pickup; can be sanded but not polished to gloss; paint only over abraded, dry surfaces.
Can G5-G9 be formed, bent or molded?
Supplied as fully cured flat sheet, rod or tube; no post-forming possible, all geometry by machining, punching (thin sheet, warm) or waterjet.
What is the maximum service temperature of G5-G9?
G5-G9 is rated for continuous use to about 155°C (311 °F), and briefly to 200°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in G5-G9?
Yes — G5-G9 is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- NEMA LI 1 — Industrial Laminated Thermosetting Products — NEMA (1998)
- MIL-I-24768/9 (Type GME) and /8 (Type GMG) — Plastic Sheet, Laminated, Thermosetting — US DoD (1994)
- ASTM D709 — Laminated Thermosetting Materials — ASTM (2017)
- Melamine glass-cloth laminate (G5/G9) sheet datasheet — industrial laminate producers (2023)
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.