XX Paper Phenolic Machined Parts
NEMA Grade XX is the general-purpose paper-base phenolic — the most economical laminate in the phenolic family and the historical standard for machined electrical insulators in medium-voltage switchgear, motor control centers, and utility equipment. Its paper-reinforced phenolic resin matrix machines freely and drills without delamination, making it well-suited to high-volume production of terminal boards, coil forms, bushings, and arc barriers. Federal Materials machines XX phenolic to print from stocked sheet and rod, with hot oil dip finishing standard for most electrical parts.
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- Terminal boards and panel insulators — drilled grids, routed slots, custom cutouts
- Coil forms and transformer bobbins — turned from rod on CNC lathe
- Arc barriers and interphase dividers — profiled switchgear components
- Bushings and sleeves — economical for medium-duty electrical applications
- Standoffs and spacers — round and hex, threaded or smooth bore
- Mounting plates and base plates — drilled, tapped, and counterbored to drawing
- Washers and shims — flat or step-ground, any OD/ID
- Prototype and production parts — from stock sheet or rod, same day quoting
Typical Tolerances
| Dimension type | Production tolerance |
|---|---|
| Critical turned dims (OD/ID) | ±0.001" |
| General machined dims | ±0.005" |
| Hole location (CNC milled) | ±0.003" |
| Flatness (plates ≤ 12") | ±0.005" |
Paper phenolic is slightly more variable than canvas or fiberglass grades due to its paper filler. For tighter tolerances or superior dimensional stability, consider CE (canvas phenolic) or G10. Tolerances confirmed at quoting.
Finish Options
| Finish | Description |
|---|---|
| Hot oil dip | Standard for XX phenolic — seals cut surfaces, displaces moisture, prevents edge wicking |
| As-machined | Available on request where oil contamination is a concern |
| Machined-to-spec edges | Chamfered or radiused per drawing callout |
Hot oil dip is strongly recommended for all XX phenolic parts that will see any humidity or outdoor-adjacent service. The paper filler is hygroscopic; unsealed cut edges can absorb moisture and reduce dielectric performance over time.
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 |
Materials We Stock (XX Phenolic Stock Shapes)
| Form | Sizes available | Notes |
|---|---|---|
| Sheet / plate | 0.031" – 4.000" thick; up to 48" × 96" | NEMA LI-1 Grade XX |
| Rod | ¼" – 6" diameter | For turned parts, coil forms, bushings |
| Tube | Selected OD/wall sizes | Call for availability |
All XX stock certified to NEMA LI-1 Grade XX. Material certifications available with each order. For flame-retardant paper phenolic, see Grade XXP (consult sales for availability).
Applications & Industries Served
XX paper phenolic has been the standard machined insulating material in North American electrical equipment for decades. It continues to be specified for:
- Switchgear and circuit breaker components — terminal boards, arc barriers, insulating bases
- Power transformers — insulating spacers, coil form components, lamination shims
- Electric motors — slot insulation, coil forms, end-bracket insulating components
- Motor control centers (MCCs) — bus-bar insulating supports, phase barriers
- Utility and distribution equipment — live-part insulators, pole-mount hardware
- Industrial relays and contactors — mounting plates, insulating bases
- MRO replacement parts — exact-replacement machined parts for legacy equipment where XX was originally specified
For new designs requiring UL-listed flame retardancy, consider Grade XXP (flame-retardant paper phenolic) or Grade FR4 fiberglass. For applications where moisture exposure is significant or impact resistance is important, consider CE canvas phenolic. If you are unsure which phenolic grade to specify, our application engineers will review your application requirements and recommend the correct grade before we quote.
Quality & Inspection
- Dimensional inspection — in-process and final; CMM first-article on request
- Dielectric withstand testing — hipot/megohm testing for insulator applications (specify on RFQ)
- Hot oil dip process log — oil temperature, immersion time tracked per batch
- Visual inspection — delamination, chip-out, edge condition
- Material C of C — NEMA LI-1 XX grade traceability with each shipment
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Request a Quote →More Related Guides
- CE Phenolic Machined Parts — canvas-reinforced electrical grade
- G10 Machined Parts — fiberglass/epoxy for higher performance
- Custom Machined Standoffs
- Custom Machined Washers
- CNC Milling Thermoset Sheet