FR4 Machined Parts
FR4 is the flame-retardant grade of woven-glass/epoxy laminate — mechanically similar to G10 but distinguished by its brominated epoxy resin system that earns a UL94 V-0 rating. When your assembly must meet flammability requirements for UL-listed equipment, FR4 is the correct laminate choice. Federal Materials machines FR4 to print from certified stock, with full material traceability and dielectric testing available for every order.
FR4 and G10 are not interchangeable for regulated applications: FR4 carries the flame-retardant listing; G10 does not. Specify FR4 on your drawing or RFQ when flammability compliance is required.
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- PCB carrier plates and test fixture plates — precision-drilled, routed to profile
- Electrical insulators and separator plates — contoured and flat, UL-listed material
- Standoffs and spacers — round and hex, threaded or smooth bore
- Switchgear components — arc barriers, phase barriers, interphase dividers
- Terminal boards — drilled grid patterns, slotted, custom cutouts
- Structural brackets for electrical enclosures — drilled and tapped mounting features
- Custom washers and shims — any OD/ID, stepped or flat
- Prototype and short-run parts — from sheet or machined-rod blanks
Typical Tolerances
| Dimension type | Production tolerance |
|---|---|
| Critical turned dims (OD/ID) | ±0.0005" |
| General machined dims | ±0.005" |
| Hole location (CNC milled) | ±0.002" |
| Flatness (plates ≤ 12") | ±0.003" |
| Surface finish | 125 µin Ra standard; finer on request |
First-article CMM reports are available. Request FAI documentation on your RFQ.
Finish Options
| Finish | Description |
|---|---|
| As-machined | Clean FR4 surface, deburred, edges broken per standard |
| Chamfered / radiused edges | Per drawing callout |
| Edge routing | Profile-routed contours for panel and PCB carrier shapes |
| No plating or coating | FR4 does not require surface treatment for most applications |
The UL94 V-0 rating applies to the base laminate. Consult your application engineer before applying surface coatings that may affect the flammability listing.
Standard Turnaround
| Stage | Lead time |
|---|---|
| Quote response | Same business day |
| Prototype / first article (1–5 pcs) | 3–5 business days |
| Short run (6–50 pcs) | 5–10 business days |
| Production run (50+ pcs) | 10–15 business days |
Expedite options available — note urgency on your RFQ. Lead times assume stock material on hand.
Materials We Stock (FR4 Stock Shapes)
| Form | Sizes available | Notes |
|---|---|---|
| Sheet / plate | 0.031" – 2.000" thick; up to 48" × 96" | NEMA FR4, UL94 V-0 |
| Rod | ¼" – 4" diameter | CNC turned for round and threaded parts |
| Custom sawn blanks | Thickness × width as needed | Reduces setup on short runs |
All FR4 stock is certified NEMA LI-1 Grade FR4 (or equivalent MIL-I-24768) and carries UL94 V-0 flammability recognition. Material certifications ship with every order.
Applications & Industries Served
FR4 machined parts are required wherever a UL-listed assembly demands a flame-retardant insulating component:
- UL-listed electrical panels and enclosures — insulating plates, separators, bus supports
- Circuit breakers and contactors — arc barriers, phase insulators, standoffs in rated assemblies
- PCB test fixtures and burn-in fixtures — precision-drilled carrier plates and fixture boards
- Motor control centers (MCCs) — bus-bar insulation, phase barriers requiring UL compliance
- Industrial switchgear — insulating components for UL 508A and NEMA 12 enclosures
- Commercial and institutional electrical equipment — components in UL-recognized or listed products
- Aerospace ground support equipment — FR4 meets MIL-I-24768 and provides flame retardancy for ground-support electrical assemblies
When your assembly is UL-listed, substituting G10 for FR4 without engineering review voids the listing. When FR4 is specified on a drawing, we supply FR4 — with UL file documentation available on request.
Quality & Inspection
- Dimensional inspection — in-process and final; CMM first-article available
- Dielectric withstand testing — hipot and dielectric breakdown testing for insulating applications (specify on RFQ)
- UL material traceability — C of C with UL file number reference available on request
- Visual inspection — delamination, crazing, burr-free edges, surface finish
- Lot traceability — heat/lot tracked from raw stock to shipped part
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Request a Quote →More Related Guides
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- CNC Turning Thermoset Rod