G7 Sheet — Thicknesses, Sizes & Stock Forms
G7 sheet is flat laminate stock produced from NEMA G-7, a glass-fiber reinforced silicone resin thermoset rated for continuous service to 220 °C (425 °F) — the highest operating temperature of any standard NEMA glass-laminate grade. Its silicone resin matrix gives G7 sheet exceptional arc resistance, low dielectric loss at elevated temperatures, and outstanding resistance to thermal degradation over long service lives. G7 sheet is specified for arc barrier plates, high-temperature insulation panels, motor end-turn separators in Class H and Class C insulation systems, and structural dielectric plates in industrial furnace equipment.
At a glance:
- Thickness range: 0.020" to 4.0"
- Standard sheet sizes: 36" × 48" and 48" × 96"
- Thickness tolerance: ±10% on thicknesses ≤ 0.062"; ±0.005" on thicker stock
- Material: NEMA G-7, woven glass-fabric/silicone thermoset laminate
- Production method: Compression-molded flat laminate
- Color: Natural off-white to light tan
Standard Thickness Table
G7 sheet is stocked in the following standard gauges at Ready Plastics:
| Thickness | Sheet Size | Notes |
|---|---|---|
| 0.031" | 36" × 48" | Thin arc barrier / liner |
| 0.062" | 36" × 48" & 48" × 96" | Motor slot liners, Class H systems |
| 0.093" | 36" × 48" & 48" × 96" | |
| 0.125" | 36" × 48" & 48" × 96" | Standard — broad application |
| 0.250" | 36" × 48" & 48" × 96" | Structural and insulation panels |
| 0.500" | 36" × 48" & 48" × 96" | Heavy insulation and barrier plates |
| 0.750" | 36" × 48" | |
| 1.000" | 36" × 48" | Thermal barrier / fixture plate |
Custom thicknesses and slit widths are available on request.
Mechanical & Electrical Properties
| Property | Value |
|---|---|
| Tensile strength | 45,000 psi (310 MPa) |
| Flexural strength (LW, 0.125") | 25,000 psi (170 MPa) |
| Shear strength | 17,000 psi (115 MPa) |
| Bond strength | 900 psi (6.2 MPa) |
| Hardness (Rockwell M) | 105 |
| Izod impact strength (49 °C, LW) | 6.50 ft·lb/in |
| Specific gravity | 1.78 |
| Water absorption (24 hr) | 0.20% |
| Flammability rating | UL 94V-0 |
| Maximum continuous service temp | 220 °C (425 °F) |
Note: G7's mechanical values are lower than G11 or FR5; select G7 when arc resistance and extreme-temperature performance are the design drivers, not peak structural load.
Typical Applications
G7 sheet is cut and fabricated into insulation components operating in the most demanding thermal environments:
- Arc barrier plates in medium-voltage circuit breakers and switchgear — silicone matrix resists carbonization from sustained electrical arcing
- Motor end-turn insulation and phase separators in Class H (180 °C) and Class C (220 °C) insulation systems
- High-temperature transformer barrier boards — maintains dielectric integrity and dimensional stability at sustained high temperatures
- Insulation plates in industrial process heating equipment — 220 °C rating covers process ovens, furnace interiors, and heat-treating fixtures
- Structural dielectric panels in turbine generator lead connections and large rotating machine components
- Aerospace and defense insulation components where extreme thermal range and arc resistance are specified
Machining G7 Sheet
G7 sheet is cut and routed on the same equipment used for G10 and G11. Waterjet cutting is preferred for complex profiles — it yields clean, burr-free edges without generating silica dust. When sawing, use carbide-tipped blades with fine teeth and steady feed rates; the silicone resin is moderately abrasive on tooling. Routing with solid carbide spiral upcut bits at moderate speeds produces smooth edge finishes appropriate for high-voltage applications. Dust collection is important when machining G7 — silica-containing glass-fiber dust requires appropriate respiratory protection. Finished parts bond well with silicone-compatible epoxy or RTV silicone adhesives.
Related
- G7 Glass Silicone — Line Card
- G7 Rod — round bar for arc-resistant insulators and high-temp machined components
- G7 Tube — hollow sections for extreme-temperature sleeves and coil forms
- G11 Sheet — high-temperature epoxy-glass sheet for 180 °C applications