Electrical insulator. Dimensionally stable. Machinable thermoset.
Phenolic laminate (Bakelite, Garolite XX/CE/LE) combines phenolic resin with paper, canvas, or linen reinforcement. Electrical insulator with excellent dimensional stability and machinability. Workhorse material for electrical standoffs, transformer insulation, and industrial jigs.
At a glance
- Density
- 1.35 g/cc
- Tensile strength
- 80 MPa
- Flexural modulus
- 7.6 GPa
- Hardness
- M 110 Rockwell
- HDT
- 150 °C
- Dielectric strength
- 11 kV/mm
- Water absorption
- 1.5%
- Flammability
- UL 94 V-0 available
Key data
- Density
- 1.35 g/cc
- Tensile strength
- 80 MPa
- Flexural modulus
- 7.6 GPa
- Hardness
- M 110 Rockwell
- HDT
- 150 °C
- Dielectric strength
- 11 kV/mm
- Water absorption
- 1.5%
- Flammability
- UL 94 V-0 available
Phenolic grades.
XX Paper
Paper-reinforced phenolic. Best electrical properties, cost-effective. Used for electrical panels, transformer insulation, general electrical hardware.
CE Canvas
Canvas-reinforced phenolic. Better mechanical properties than paper grades. Used for mechanical jigs, insulator blocks, structural electrical.
LE Linen
Linen-reinforced phenolic. Fine weave enables precision machining. Best for fine-feature machining, clock gears, precision jigs.
G3 Glass
Glass-cloth reinforced phenolic. Highest temperature (185 °C) and strongest. Used for high-temperature electrical insulation.
G5 / G7 Glass-Silicone
Silicone-phenolic with glass cloth. Higher temperature rating (220 °C). For aerospace electrical and specialty high-temperature applications.
MC Mica Filled
Mica-filled phenolic for arc resistance. Used in electrical switchgear, high-voltage insulation, arc chute applications.
Different reinforcement materials produce different mechanical and electrical properties. Paper-based for electrical, canvas for general mechanical, linen for precision machining.
Why phenolic endures.
Electrical insulator
11 kV/mm dielectric strength. Industry standard for transformer insulation, electrical standoffs, switchgear components.
Dimensionally stable
Thermoset polymer — doesn't creep, doesn't soften with temperature. Precision jigs and fixtures hold tolerance indefinitely.
Machinable
Cuts cleanly with carbide tooling. Holds threads. Accepts inserts. More machinable than most filled thermoplastics.
Cost effective
Base phenolic material $5-15/kg — cheapest structural plastic. For electrical and industrial applications where premium plastics aren't needed.
Despite being an old material, phenolic laminate remains the cost-effective choice for electrical insulation and industrial applications where modern plastics are overkill.
Phenolic applications.
Transformer insulation
XX paper phenolic bobbins, spacers, insulation bars for power transformers
Electrical standoffs
CE canvas phenolic standoffs for panels, electrical enclosures
Industrial jigs
LE linen phenolic precision jigs, fixtures, gauge blocks
Clock gears
LE phenolic gears for timepiece mechanisms — quiet, dimensionally stable
Electrical panels
Phenolic panel backing boards for breakers, relays, connectors
High-voltage insulators
G3/G5 glass phenolic for HV electrical insulation
Arc-resistant hardware
MC mica phenolic for switchgear arc chutes, interrupters
Structural insulators
Phenolic structural spacers in high-voltage transformers
Machine tool parts
Phenolic wear strips, guides, insulator blocks in machinery
Phenolic finishing.
As-machined
Dark brown color. Clear fiber pattern visible on finished surface. Ra 1.6 µm typical.
Sanded
Manual sanding achievable for improved cosmetic finish.
Painted
Accepts standard paints. Light sanding improves adhesion.
Machined threads
Threads hold in phenolic. Inserts recommended for high-cycle fasteners.
Pressed inserts
Threaded metal inserts pressed or epoxied into phenolic.
Laser marked
Good contrast on phenolic surface. Standard for part identification.
Waxed
Wax finish for decorative applications or improved dimensional stability in humid environments.
Beveled edges
Sharp edges chip easily — chamfer or radius preferred.
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Electrical insulator — questions
Bakelite vs phenolic — same thing?
Bakelite is the original brand name for phenol-formaldehyde thermoset from 1907 — the first synthetic plastic. Modern "Bakelite" often refers to pure phenolic molding compound. "Phenolic laminate" or "industrial phenolic" refers to reinforced phenolic with paper/canvas/linen. They're all phenol-formaldehyde thermosets but with different reinforcement. For CNC machining applications, specify "phenolic laminate" with desired reinforcement (XX, CE, LE).
Phenolic vs G10/FR4?
Phenolic: phenol-formaldehyde resin with paper/canvas/linen reinforcement. Cheaper, older technology. G10/FR4: epoxy resin with glass cloth reinforcement. Better mechanical, electrical, and moisture properties. G10/FR4 has largely replaced phenolic in new designs. Phenolic remains cost-effective for legacy electrical applications and non-critical industrial uses. For new designs: specify G10/FR4 unless specific phenolic property needed.
Machining hazards?
Phenolic dust contains phenol (a known irritant). Requires: dust extraction, respiratory PPE, avoid inhalation of fine dust. Chips are friable and airborne-prone. Compared to nylon or Delrin, phenolic machining requires more dust control. Our phenolic work is isolated to dedicated machining area with HEPA extraction. Finished phenolic parts are safe to handle.
Moisture absorption issues?
Phenolic absorbs 0.5-1.5% moisture, dimensionally growing about 0.1-0.3% when wet. For outdoor or high-humidity service, moisture effects can cause tolerance drift over time. Mitigation: post-machining sealing (wax, paint, epoxy coating), or specify glass-reinforced grades (G3, G5) which have lower moisture absorption. For dry indoor service, standard phenolic is dimensionally stable.
Temperature limits?
Standard phenolic (XX, CE, LE): continuous service 120-150 °C. G3 glass phenolic: 185 °C continuous. G5 silicone-phenolic: 220 °C continuous. Beyond these limits, phenolic undergoes thermal decomposition — charring and property loss. For very high temperature, specify glass-reinforced or switch to specialty high-temperature plastics (PEI, PEEK, Vespel).
Production lead times?
Standard phenolic grades: in stock or 1-week lead time. Specialty grades (G5, MC): 2-3 week material lead time. Machining time similar to Delrin — efficient, fast. Typical complete order: 7-14 days from PO to ship. Phenolic manufacturing is mature and predictable — no surprises in lead time.
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