Carbon Fiber Fabric Specification Guide for Buyers

“Carbon fiber fabric” is not a complete purchase specification. Two fabrics can share a similar appearance while differing in fiber grade, tow size, weave, areal weight, width, sizing, roll construction, and suitability for a given resin process. If these fields are missing, suppliers must guess, and quotations may not describe comparable products.

This guide turns a general request into a reviewable specification. It is intended for dry woven reinforcement. Prepreg, unidirectional tape, braided products, and multiaxial non-crimp fabrics need additional fields.

The Minimum Specification Stack

Not every project must control every field tightly. The point is to mark each field as required, preferred, open to supplier proposal, or not applicable.

1. Define the Fiber Without Over-Specifying It

If an engineering drawing requires a specific grade, write it. If the requirement is performance-based, state the property, test method, and acceptance basis instead of copying a brand name without context. Also clarify whether an equivalent grade can be proposed and what evidence is needed to review equivalence.

The current product catalog identifies carbon fiber twill cloth and plain cloth as 200 g/m² T300 products. That is enough to identify a catalog starting point, but an application approval still needs the current product data and the project's own laminate validation.

2. State Tow Size When It Is a Real Requirement

Tow notation describes the approximate filament count in a carbon bundle: 3K means about 3,000 filaments, 6K about 6,000, and 12K about 12,000. Buyers commonly use tow size to control the visual scale and construction of woven cloth, but tow alone does not define finished fabric performance.

Specify tow when it affects appearance, weave geometry, handling, downstream equipment, or an approved design. Otherwise, allow the supplier to identify the tow used in the proposed construction and evaluate the complete fabric data.

3. Choose Weave by Geometry and Handling

Plain weave interlaces each direction frequently, which generally gives a stable fabric. A 2x2 twill has a diagonal pattern and can conform more readily to some curved surfaces. The right selection depends on tool geometry, cut-piece size, handling, cosmetic needs, and the laminate schedule.

Use a process trial rather than assuming a weave will drape around every compound curve. The existing twill versus plain weave guide provides a more detailed handling comparison, but its general guidance does not replace a trial on the actual tool.

4. Do Not Confuse GSM with Thickness

Areal weight reports fiber mass per unit area. Cured laminate thickness also depends on fiber density, weave, resin content, compaction, voids, and the number of plies. A request for “200 GSM, 1 mm thick” is incomplete unless it explains whether 1 mm refers to one dry ply, a cured laminate, or a finished part.

For purchasing, state the nominal GSM and its allowed tolerance. For laminate engineering, separately define ply count, cured thickness target, fiber volume or resin-content control if used, and the test method.

5. Specify Usable Width and Roll Construction

State the minimum usable width rather than only the loom or nominal width. Include edge treatment, allowable edge distortion, core size, roll length or roll mass, maximum outer diameter if equipment has a limit, and whether splices are permitted. If automated cutting is planned, provide the nesting width and any orientation constraints.

These details often decide whether a lower unit price is actually usable in production.

6. Match Sizing, Resin, and Process

Tell the supplier the resin family and production method. If a specific sizing is already approved, identify it. If not, ask the supplier to state the sizing and its intended resin compatibility. Do not describe a dry woven cloth as “compatible with every resin” without supporting data for the proposed combination.

Useful process details include:

• open or closed mold;
• hand placement or automated handling;
• infusion path and expected flow direction;
• room-temperature or heated processing;
• whether the fabric will be converted to prepreg;
• surface finish and porosity acceptance.

7. Turn Appearance into Acceptance Criteria

For visible carbon parts, “good appearance” is too subjective. Define which face is inspected, pattern alignment, maximum bow or skew, allowable gaps, broken tows, fuzz, contamination, discoloration, edge condition, and how much of a roll may contain marked defects. If color matching matters, approve a physical limit sample under a defined light source.

For internal structural plies, cosmetic limits may be unnecessary, but contamination, damage, width, mass, and traceability can still matter.

8. List Documents Before the Quote

Required documentation changes price, lead time, and supplier qualification effort, so put it in the RFQ. Possible items include a technical data sheet, safety data where applicable, certificate of analysis or conformity, lot traceability, test reports, restricted-substance declaration, packing list fields, and country-of-origin information.

Ask only for documents that the project will review. A long generic list can create cost without improving control.

Copy-and-Use Fabric Specification

Product: dry woven carbon fiber fabric
Application / part:
Fiber grade or property basis:
Equivalent grades allowed: yes / no / subject to review
Tow size:
Weave:
Nominal areal weight and tolerance:
Minimum usable width and tolerance:
Sizing / approved resin compatibility:
Resin system:
Manufacturing process:
Cosmetic face and defect limits:
Roll length or mass, core and splice rule:
Annual / trial quantity and order unit:
Packaging and label fields:
Required quality and compliance documents:
Sample or first-article approval plan:
Delivery destination and requested date:

Quote Review Checklist

Before comparing prices, confirm that every proposal states the same unit, usable width, weight tolerance, roll basis, packaging, document scope, and delivery term. Flag every supplier exception. If one quote leaves tow, sizing, tolerance, or splice policy blank, it is not yet directly comparable with a fully defined offer.

Use the broader carbon fiber versus fiberglass selection guide if the reinforcement family is still open. When the fabric choice is established, move the completed fields into the composite reinforcement RFQ checklist and submit them through the contact page.

If tow count is still an open field, use the 3K, 6K, and 12K carbon fiber tow guide before comparing supplier offers.