G5
ASTM D709, D709 Grade G-5 · also Melamine Glass Laminate
G5 is a melamine-resin glass-fabric NEMA laminate (ASTM D709 Grade G-5, similar to EN 60893 MP GC 201) combining high mechanical strength, surface hardness and arc resistance.
Values for the Melamine Matrix condition
G5 grades and fills
G5 is supplied in 2 conditions, soft to hard. Melamine Matrix is the default FabDigit quotes; the values on this page are for it.
Compare all 2 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Melamine MatrixDefault G5 glass-cloth melamine laminate (NEMA G5 / MIL GME) | Standard choice when arc resistance, tracking resistance and inherent flame retardance matter more than humid-state electrical stability. | 220 | 1.5 | 115 HRM | |
Melamine glass-cloth laminate, improved humid-state electricals | Pick G9 over G5 when the part must hold dielectric strength and insulation resistance after humidity exposure while keeping melamine's arc/tracking resistance. | 240 | 1.5 | 118 HRM |
What is G5?
G5 is a melamine-resin glass-fabric NEMA laminate (ASTM D709 Grade G-5, similar to EN 60893 MP GC 201) combining high mechanical strength, surface hardness and arc resistance. It reaches about 220 MPa tensile strength with service to 150 °C, and is stocked as sheet, rod and tube for punched or machined electrical parts such as arc barriers and insulators. The hard melamine/glass system is difficult to cut (machinability rating 25), so tooling cost is high, and unsealed edges pick up moisture, which lowers electrical performance. G9 covers the same system at a higher heat rating; G-10/G-11 machine more easily where arc resistance is not the driver. G5 has a density of 1.95 g/cm³ (0.0704 lb/in³), heavier than 75% of composite grades. G5 has a tensile strength of 220 MPa (31.9 ksi), weaker than 53% of composite grades. Elongation at break is 1.5% and the elastic modulus is 17 GPa (2.47 Msi).
What is G5 used for?
- Arc barriers
- Switchgear insulators
- Terminal blocks and boards
- Punched washers and spacers
- Contactor and circuit breaker components
- Bus bar supports
Advantages
- Low embodied carbon — 4.5 kg CO₂/kg, better than 79% of composite grades
Limitations
- Needs corrosion protection — 58/100, worse than 83% of composite grades
G5 properties
Typical room-temperature values for G5-Melamine Matrix; bars are the position among composite grades.
Physical3
G5 has a density of 1.95 g/cm³ (0.0704 lb/in³), heavier than 75% of composite grades.
Mechanical13
G5 has a tensile strength of 220 MPa (31.9 ksi), weaker than 53% of composite grades. Elongation at break is 1.5% and the elastic modulus is 17 GPa (2.47 Msi).
Thermal9
G5 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 50% of composite grades. Thermal expansion is 14 µm/m·K (7.78 µin/in·°F).
Electrical7
G5 is an electrical insulator with a dielectric strength of 15 kV/mm (381 V/mil) and a resistivity of 1×10¹¹ Ω·m.
Chemical & Environmental3
Corrosion resistance is good (58/100), worse than 83% of composite grades. UV resistance is fair.
Sustainability3
Producing a kilogram of G5 takes about 75 MJ of energy and emits 4.5 kg of CO₂ — less than 91% of composite grades. Typical recycled content is 0%.
Manufacturability4
G5's machinability is poor (25/100, worse than 65% of composite grades); weldability not recommended (0/100); formability not recommended (5/100).
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 composite family
Yield strength against density for every composite grade FabDigit runs. G5 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with G5
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.
Manufacturability
The process limits FabDigit's quote engine applies to G5. Design inside these and the part quotes instantly; outside them it routes to an engineer.
CNC machining
| Machinability | Better25 / 100 |
|---|---|
| Cutting speed (rough / finish) | — / — |
| Minimum wall | — |
| Minimum internal radius | — |
| Drill depth limit | |
| Best surface (machined / polished) | Ra — / — |
| Hardenable after machining | — |
Sheet metal
| Formability | Not Recommend5 / 100 |
|---|---|
| Weldability | Not Recommend0 / 100 |
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) |
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.
Surface treatments FabDigit runs on composite 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).
Organic Coating
Equivalent designations
Standards and trade names that resolve to G5 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- ASTM
- D709D709 Grade G-5
- Trade names
- Melamine Glass Laminate
- Also called
- NEMA G-5
How much does G5 cost?
G5 is a premium-cost composite ($$$), pricier than about 58% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
G5 — frequently asked
What is G5 used for?
G5 is typically used for arc barriers, switchgear insulators, terminal blocks and boards, punched washers and spacers, contactor and circuit breaker components and bus bar supports. In short: melamine arc-resistant laminate.
What is the tensile strength of G5?
G5 has a typical tensile strength of 220 MPa (31.9 ksi) — weaker than 53% of composite grades. Strength varies by condition: see the 2 listed tempers.
Is G5 easy to machine?
Not especially — machinability is rated poor (25/100, worse than 65% of composite grades). Machine dry with sharp carbide or diamond tooling, high speed / moderate feed, backing plate to avoid edge chipping and delamination; provide dust extraction (glass + melamine dust is irritant).
Can G5 be welded?
Not readily — weldability is rated not recommended (0/100). Not weldable — thermoset laminate; join by bolting, riveting or epoxy bonding after abrading and solvent-cleaning the surface.
What surface finishes work on G5?
Edges should be deburred and sealed with varnish or epoxy to limit moisture pickup; can be sanded but not polished to gloss; paint only over abraded, dry surfaces.
Can G5 be formed, bent or molded?
Supplied as fully cured flat sheet, rod or tube; no post-forming possible, all geometry by machining, punching (thin sheet, warm) or waterjet.
What is the maximum service temperature of G5?
G5 is rated for continuous use to about 150°C (302 °F), and briefly to 200°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does G5 cost?
G5 is a premium-cost composite ($$$), pricier than about 58% 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 G5?
Yes — G5 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; 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.