G9 Phenolic Glass Melamine Specifications & Sizes
NEMA G9 phenolic glass melamine is produced to NEMA LI 1 (commercial) and MIL-I-24768/2 Type GME (military) specifications. This page consolidates governing standards, available forms and sizes, dimensional tolerances, and test method references — the working reference for purchasing engineers and design engineers specifying G9 stock or custom fabrications.
At a Glance
- Governing standard: NEMA LI 1 Grade G9 (commercial); MIL-I-24768/2 Type GME (military)
- ASTM standard: ASTM D709 (Standard Specification for Laminated Thermosetting Materials)
- Forms: sheet, rod, tube
- Sheet thickness range: 0.031 in – 4.000 in standard
- Rod diameter range: 0.250 in – 6.000 in standard
- Tube OD range: 0.500 in – 12.000 in (various wall thicknesses)
- Color: natural beige
- Flatness: ≤0.010 in/ft for sheet ≤1.000 in thick (commercial); tighter for mil-spec
Governing Standards
NEMA LI 1
NEMA LI 1 (Industrial Laminated Thermosetting Products) is the primary U.S. commercial standard for thermoset laminates. Section relevant to G9:
- Grade G9: woven glass cloth, melamine resin
- Defines minimum property thresholds (electrical, mechanical, moisture) by test method
- Does not mandate lot testing — that is left to procurement specification
MIL-I-24768/2 Type GME
The military specification MIL-I-24768 covers electrical insulating materials for military and naval equipment. Relevant clauses for G9:
- Type GME = glass melamine (identical resin/reinforcement to NEMA G9)
- Mandates lot-by-lot testing: arc resistance, dielectric strength, flexural strength
- Requires traceability to a Qualified Products List (QPL) manufacturer
- Specifies tighter thickness tolerance bands than commercial NEMA
- Requires a Certificate of Conformance (C of C) per lot
ASTM D709
ASTM D709 is the test-method companion to NEMA LI 1, defining how mechanical and electrical properties of laminate sheets are measured. Key test methods cited in G9 specs:
| Property | Test Method |
|---|---|
| Dielectric strength | ASTM D149 |
| Dielectric constant / dissipation factor | ASTM D150 |
| Volume / surface resistivity | ASTM D257 |
| Arc resistance | ASTM D495 |
| Tensile strength | ASTM D638 |
| Flexural strength / modulus | ASTM D790 |
| Compressive strength | ASTM D695 |
| Water absorption | ASTM D570 |
| Izod impact | ASTM D256 |
| Density | ASTM D792 |
Sheet Specifications
Standard Thicknesses
| Thickness (in) | Thickness (mm) | Stock Status |
|---|---|---|
| 0.031 | 0.79 | Stock |
| 0.062 | 1.57 | Stock |
| 0.093 | 2.36 | Stock |
| 0.125 | 3.18 | Stock |
| 0.187 | 4.75 | Stock |
| 0.250 | 6.35 | Stock |
| 0.375 | 9.53 | Stock |
| 0.500 | 12.70 | Stock |
| 0.750 | 19.05 | Stock |
| 1.000 | 25.40 | Stock |
| 1.500 | 38.10 | Made to order |
| 2.000 | 50.80 | Made to order |
| 3.000 | 76.20 | Made to order |
| 4.000 | 101.60 | Made to order |
Standard Sheet Panel Sizes
- 36 × 48 in (standard panel, most stock thicknesses)
- 48 × 96 in (full sheet, thicknesses 0.062 in and above)
- Custom panel sizes available with minimum order quantities
Sheet Thickness Tolerances (Commercial NEMA)
| Nominal Thickness (in) | Tolerance |
|---|---|
| 0.031 – 0.093 | ±0.005 in |
| 0.125 – 0.250 | ±0.008 in |
| 0.375 – 0.750 | ±0.012 in |
| 1.000 – 2.000 | ±0.020 in |
| >2.000 | ±1.0% |
MIL-I-24768/2 Type GME imposes tighter tolerances; confirm with supplier at time of order.
Flatness
Commercial G9 sheet: ≤0.010 in/ft (flatness deviation from a reference plane) for thicknesses ≤1.000 in. Thicker plate may show greater bow — specify maximum allowable bow if critical to assembly.
Rod Specifications
Standard Diameters
| Diameter (in) | Standard Length |
|---|---|
| 0.250 | 48 in |
| 0.375 | 48 in |
| 0.500 | 48 in |
| 0.625 | 48 in |
| 0.750 | 48 in |
| 1.000 | 48 in |
| 1.250 | 48 in |
| 1.500 | 48 in |
| 2.000 | 48 in or 96 in |
| 2.500 | 48 in |
| 3.000 | 48 in |
| 4.000 | 48 in |
| 5.000 | 48 in |
| 6.000 | 48 in |
Rod Diameter Tolerances
Commercial as-extruded rod: +0.000 / −0.030 in for diameters ≤1.000 in; ±0.020 in for diameters >1.000 in. Turned and ground rod (tighter tolerance): ±0.003 in, available on request with extended lead time.
Tube Specifications
G9 tubes are filament-wound or hand-laid from glass-cloth prepreg and cured under pressure. Mechanical and electrical properties are equivalent to flat laminate.
Standard Tube Sizes
OD ranges from 0.500 in through 12.000 in. Common wall thicknesses: 1/8 in, 3/16 in, 1/4 in, 3/8 in, 1/2 in. Custom OD/ID combinations available. Contact supplier for specific dimensional availability — tube is a less-standardized form than sheet or rod.
Tube Tolerances
OD tolerance: ±0.030 in for OD ≤4.000 in; ±0.050 in for OD >4.000 in. ID tolerance: ±0.030 in. Wall thickness concentricity: ≤0.020 in eccentricity for standard tubes.
Electrical Specification Summary
The following table summarizes the minimum electrical properties per NEMA LI 1 Grade G9 that procurement documents should cite:
Certification and Documentation
For commercial NEMA G9:
- Manufacturer's Certificate of Compliance referencing NEMA LI 1 Grade G9
- Material Safety Data Sheet (SDS)
- Dimensional inspection report (on request)
For MIL-I-24768/2 Type GME:
- Certificate of Conformance with lot number
- Lot-specific test report (arc resistance, dielectric strength, flexural strength)
- QPL qualification evidence
- Traceability documentation per MIL-STD-45662
For machined parts sourced from G9 stock, retain the laminate C of C as material traceability documentation throughout the manufacturing chain.
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