C
ASTM D709 Grade C, D709 Type C · GB 4021
C is a coarse-weave cotton-fabric phenolic laminate to ASTM D709 Grade C (also listed as 4021, PF CC 201 to IEC 60893 and Hgw 2072).
Reference datasheet — C is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
C grades and fills
C is supplied in 2 conditions, soft to hard.
Compare all 2 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Graphite / MoS₂ filled bearing grade cotton phenolic | Choose for dry or marginally lubricated bearings, thrust washers and marine stern-tube bushes needing a low, stable friction coefficient. | 60 | 1.2 | 88 Shore D | |
Flame-retardant modified cotton phenolic | Specify where rail, transit or enclosure fire codes demand a V-0 / low-smoke laminate rather than standard HB Grade C. | 70 | 1.3 | 89 Shore D |
Supply forms, finishes and certifications
Ways C is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
ROD | Rolled/moulded cotton-fabric phenolic round bar | Supply form |
SHEETDefault | Sheet / plate | Supply form |
TUBE | Convolute-wound cotton-fabric phenolic tubing | Supply form |
What is C?
C is a coarse-weave cotton-fabric phenolic laminate to ASTM D709 Grade C (also listed as 4021, PF CC 201 to IEC 60893 and Hgw 2072). The cotton fabric gives good impact resistance and the best machinability in this laminate family (score 70), so it is used for machined mechanical parts made from pressed sheet, rolled rod and wound tube, including graphite-filled and flame-retardant conditions. Tensile strength is 76 MPa and maximum service temperature 120 °C, and cut edges pick up moisture unless sealed. Where higher strength or temperature is required, move to G-10/FR-4. C has a density of 1.36 g/cm³ (0.0491 lb/in³), lighter than 70% of composite grades. Its glass-transition temperature is 160°C (320 °F). C has a tensile strength of 76 MPa (11 ksi), weaker than 78% of composite grades. Elongation at break is 1.5% and the elastic modulus is 7 GPa (1.02 Msi).
What is C used for?
- gears and bearings
- mechanical brackets
- wear pads
- structural insulation parts
Advantages
- Low embodied carbon — 4.5 kg CO₂/kg, better than 79% of composite grades
- Easy to machine — 70/100, better than 77% of composite grades
Limitations
- Absorbs moisture — dry before molding — 1.6%, worse than 84% of composite grades
- Limited service temperature — 120°C (248 °F), worse than 78% of composite grades
- Low stiffness — 7 GPa (1.02 Msi), worse than 77% of composite grades
C properties
Typical room-temperature values; bars are the position among composite grades.
Physical4
C has a density of 1.36 g/cm³ (0.0491 lb/in³), lighter than 70% of composite grades. Its glass-transition temperature is 160°C (320 °F).
Mechanical12
C has a tensile strength of 76 MPa (11 ksi), weaker than 78% of composite grades. Elongation at break is 1.5% and the elastic modulus is 7 GPa (1.02 Msi).
Thermal8
C is rated for continuous service to 120°C (248 °F). It conducts heat at 0.3 W/m·K (0.173 BTU/hr·ft·°F), worse than 63% of composite grades. Thermal expansion is 25 µm/m·K (13.9 µin/in·°F).
Electrical7
C is an electrical insulator with a dielectric strength of 10 kV/mm (254 V/mil) and a resistivity of 1×10⁹ Ω·m.
Chemical & Environmental3
Corrosion resistance is very good (70/100), worse than 64% of composite grades. UV resistance is fair.
Sustainability4
Producing a kilogram of C takes about 78 MJ of energy and emits 4.5 kg of CO₂ — less than 87% of composite grades. Typical recycled content is 0%.
Manufacturability2
C's machinability is very good (70/100, better than 77% of composite grades).
Common Calculations4
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the composite family
Yield strength against density for every composite grade FabDigit runs. C is highlighted; hover a dot for its name, or open the interactive family chart.
Working with C
Is C easy to machine?
Machines readily with sharp carbide or PCD tooling at high speed and low feed; dust is abrasive and irritating, so use extraction and avoid coolant soak that swells the cotton.
Can C be welded?
Not weldable — thermoset; join by bolting, riveting or epoxy bonding after light abrasion and degreasing.
Can C be formed, bent or molded?
Supplied fully cured as pressed sheet, rolled rod or wound tube; no post-forming except hot-bending of very thin sheet, so parts are produced by machining.
C chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| phenol-formaldehyde (phenolic) resinresole/novolac binder, fully cured thermoset | 42 – 55 | 48 |
| cotton fabric (coarse weave, ≥ 4 oz/yd² woven cellulose carrier defines Grade C vs fine-weave CE/L | ≥ 45 (balance) |
What surface finishes work on C?
Cannot be plated or anodised; edges are sealed with varnish or epoxy to limit moisture pick-up, and surfaces can be sanded/varnished rather than polished to a mirror finish.
Equivalent designations
Standards and trade names that resolve to C in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- ASTM
- D709 Grade CD709 Type C
- GB (China)
- 4021
- Also called
- NEMA C
- Similar grades
- Hgw 2072
How much does C cost?
C is a premium-cost composite ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
C — frequently asked
What is C used for?
C is typically used for gears and bearings, mechanical brackets, wear pads and structural insulation parts. In short: best-machining phenolic laminate; impact-tough cotton phenolic; low-cost gear stock.
What is the tensile strength of C?
C has a typical tensile strength of 76 MPa (11 ksi) — weaker than 78% of composite grades. Strength varies by condition: see the 2 listed tempers.
Is C easy to machine?
Yes — machinability is rated very good (70/100, better than 77% of composite grades). Machines readily with sharp carbide or PCD tooling at high speed and low feed; dust is abrasive and irritating, so use extraction and avoid coolant soak that swells the cotton.
Can C be welded?
Not weldable — thermoset; join by bolting, riveting or epoxy bonding after light abrasion and degreasing.
What surface finishes work on C?
Cannot be plated or anodised; edges are sealed with varnish or epoxy to limit moisture pick-up, and surfaces can be sanded/varnished rather than polished to a mirror finish.
Can C be formed, bent or molded?
Supplied fully cured as pressed sheet, rolled rod or wound tube; no post-forming except hot-bending of very thin sheet, so parts are produced by machining.
What is the maximum service temperature of C?
C is rated for continuous use to about 120°C (248 °F), and briefly to 150°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does C cost?
C is a premium-cost composite ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ASTM D709 – Standard Specification for Laminated Thermosetting Materials — ASTM International (2023)
- IEC 60893-3-4 – Industrial rigid laminated sheets, phenolic resin (PF CC 201/203) — IEC (2013)
- NEMA LI 1 – Industrial Laminated Thermosetting Products — NEMA (2020)
- Engineered Materials Handbook, Vol. 2: Engineering Plastics — ASM International (1988)
- Cotton fabric phenolic laminate (Grade C / CE) datasheets — Norplex-Micarta / Franklin Fibre / Attwater (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.