G10 / FR-4 Epoxy Glass Insulating Washers and Spacers
Precision epoxy glass washers for terminal and busbar insulation. G10/FR-4 washers give moisture-stable insulation at terminal and busbar joints. We machine them to ID/OD and thickness with flatness held across the batch. For high volume we tool stamping and supply inspection records on request. Stamped for high volume and burr-free edges; machined when ID/OD or flatness must be tight. Arc-resista
Precision epoxy glass washers for terminal and busbar insulation. G10/FR-4 washers give moisture-stable insulation at terminal and busbar joints. We machine them to ID/OD and thickness with flatness held across the batch. For high volume we tool stamping and supply inspection records on request. Stamped for high volume and burr-free edges; machined when ID/OD or flatness must be tight. Arc-resista
Technical specifications
| Material | G10 / FR-4 epoxy glass |
| Property | Moisture stable, V-0 (FR-4) |
| Tolerance | Thickness +/-0.05 to 0.10 mm |
| Use | Terminal / busbar washers |
Information required for quotation
| Base tube | Approved material grade, ID, OD, wall and conditioning as per drawing |
| Datums | Drawing datum scheme and measurement reference |
| Key dimensions | Feature positions, depths, pitch and diameters reviewed before quotation |
| Thread / profile | Standard or custom profile, class, depth, engagement and gage method |
| Other features | Holes, slots, steps, chamfers, cuts and marking |
| Acceptance | Tolerances, sampling, gages, FAI and inspection report |
| Order | Prototype and production quantity, packaging and delivery target |
Applications by industry
- Insulating washers under busbar and device mounting bolts
- Spacer shims between live and earth metalwork
- CB terminal pad isolating washers
- High-strength flange washers in electrical machinery
- PCB standoff/insulation washers (FR-4)
- Custom-ID/OD punched washers for transformer hardware
Why G10 / FR-4 epoxy glass for this application
G10/FR-4 washers isolate hardware while carrying the clamp load of a torqued bolt, which paper phenolic alone often crushes under. Punching keeps cost low and hole concentricity repeatable.
Confirm thickness-class against crush and CTI of the surrounding duty. Punched FR-4 edge can be brittle near a tighten bolt — specify chamfered or ground if torque is high.
Standards: IPC-4101 / ASTM D709, IEC 60672, UL 94 V-0.
Feature and remaining-wall review
Diamond-coated tools for clean edges; CNC turning, grinding and drilling to drawing. Dimensional stability excellent with controlled moisture content. Review feature depth, edge distance and remaining wall against critical geometries. Capability is confirmed on your drawing, not from a blanket tolerance.
Inspection and traceability
We state the control plan with you. Batch traceability links raw material lot to finished part.
- First-article inspection (FAI) per your plan
- In-process dimensional checks at every station
- Batch certificate of conformance (COA) supplied on request
- Lot traceability to incoming material certificate
- Dielectric strength and insulation resistance testing available on request
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ECR Epoxy Fiberglass Rods
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Common questions
What voltage class can epoxy glass handle?
Dielectric strength ≥ 20 kV/mm. Voltage rating depends on thickness, geometry and safety factor — your drawing determines the insulation level.
Can epoxy glass be machined to tight tolerances?
Yes. We hold ±0.05 mm on ID/OD with CNC turning and grinding using diamond-coated tools to avoid delamination.
Is epoxy glass arc-resistant?
It has good arc resistance but is not arc-quenching. For direct arc contact, pair with ceramic-filled or synthetic arc-quenching composites.
What certifications do you provide?
Material COA, batch traceability, first-article and final inspection per your plan. Certificates comply with RoHS and REACH on request.
Stamped or machined washers?
Material COA, batch traceability, first-article and final inspection per your plan. Certificates comply with RoHS and REACH on request.
Engineering Guides & Selection Notes
Related technical articles that help specify this product.
Get pricing for G10 / FR-4 Epoxy Glass Insulating Washers and Spacers
Attach the drawing with annual volume. We check the material against your duty and tolerance, verify ID / OD / wall / features, and respond with manufacturability notes and pricing.