G10 Plate — Heavy Stock, Machined Parts & Sizes

G10 plate refers to heavy-gauge G10 glass-epoxy laminate stock — typically 1/4" (0.250") and thicker, up to 4.0" and beyond on special order. While G10 sheet covers the full range from 0.005" to 4.0", the term "plate" is conventionally applied to the heavy thicknesses where the part's structural and load-bearing role is primary rather than insulation alone. G10 plate is the starting stock for machined bus bar support blocks, structural isolation mounts, thick fixture plates, transformer winding spacers, and precision machined insulators requiring rigid cross-sections.

At a glance:

• Plate thickness range: 0.250" to 4.0" standard; heavier to order
• Standard panel sizes: 24" × 36", 36" × 48", 48" × 96"
• NEMA LI 1 Grade G10; MIL-I-24768/2 Type GEE certification available
• Flatness: 0.008"–0.010" per 12" (improves with thickness)
• Cut-to-size: rectangular blanks, CNC-machined shapes, drilled and tapped plates
• Compressive strength: 65,000 psi (flatwise) — suitable for sustained compressive loading

Plate Thickness Range and Panel Sizes

G10 plate is produced in standard press-panel sizes. Thickness tolerance tightens as plate gets thicker due to improved laminate stiffness and press control.

Standard Plate Dimensions

Common Plate Thicknesses

Plate Tolerances

Plate Properties

G10 plate properties are governed by NEMA LI 1 Grade G10. Plate stock has the same base laminate properties as thin sheet. The through-thickness direction has lower dielectric strength and higher CTE than the in-plane direction — this anisotropy must be accounted for in designs that rely on through-thickness insulation.

Structural Properties and Load Calculations

G10 plate is frequently used in load-bearing structural insulation roles where compressive and shear loads are significant.

Compressive Loading

With flatwise compressive strength of 65,000 psi, a 1" × 1" cross-section of G10 plate can carry 65,000 lbf in compression — far exceeding the compressive requirements of most isolation mount and bus bar support applications. The primary design limit in many applications is not compressive yield but creep or bearing stress at fastener holes.

Fastener Bearing Strength

Bearing strength of G10 plate (through-bolt bearing) is approximately 40,000 psi. For a 1/2"-diameter bolt through a 0.500" thick plate, the bearing area is 0.25 in², and allowable bearing load is 10,000 lbf before yielding. Use metallic inserts or washers to spread bearing loads in high-load fastener applications.

Interlaminar Shear

The weakest direction in G10 plate is interlaminar shear (between plies) at ~7,000 psi. Designs with large in-plane shear loads applied through the laminate thickness — such as T-sections or bonded lap joints — must account for this lower interlaminar value.

Machined Plate Applications

G10 plate is the starting material for precision machined insulating components:

Bus bar supports and insulators: Blocks machined from 0.500"–2.0" plate, drilled and tapped for bus bar attachment hardware. High compressive strength handles bus bar weight and mechanical shock in switchgear panels.

Transformer winding spacers and spiders: Heavy plate machined into circular winding spacers, radial cooling duct spacers, and end-frame components in power transformers.

Isolation mounting blocks: Machined blocks installed between electrically live structures and grounded frames or enclosures. G10's high dielectric strength (through-thickness) and mechanical stiffness are both required simultaneously.

Structural fixture plates: CNC machining fixtures, jig plates, and assembly templates where non-conductivity plus dimensional stability are required.

Cryogenic support structures: G10 thick plate machined into G10 struts and support blocks for superconducting magnets. Properties are maintained at liquid helium temperature (4 K).

Cut-to-Size and Machining Services

G10 plate can be supplied:

• Cut-to-size: Rectangular blanks sawn from full panels; tolerance on cut dimensions ±0.030"–0.062" depending on thickness
• CNC-machined blanks: Complex profiles, pockets, slots, and counterbores — turned-around from print
• Drilled and tapped plate: Holes drilled and tapped per drawing — carbide tooling used throughout; see G10 machining guide
• Surface-ground plate: Flatness and thickness to ±0.002"–0.005" by precision surface grinding

More related guides

Applications

• Electrical Insulators
• Structural Insulators
• Transformer Components

Industries

• Electronics
• Aerospace
• Power Generation

Compare to other materials

• G10 vs FR4
• G10 vs G11

Forms

• G10 Sheet
• G10 Rod
• G10 Tube

Frequently asked questions — G10 FAQ