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Composite Fabricating Basics Part 1: Fabric Selection

Step One: Fabric Selection

Types of Fabric Weave Style and Surface Finishing for Resin Type Compatibility 

Fabrics are generally considered ”balanced” if the breaking strength is within 15% warp to fill and are best in bias applications on lightweight structures. “Unbalanced” fabrics are excellent when a greater load is required one direction and a lesser load in the perpendicular direction.

Tow The bundle of individual carbon filaments used to weave carbon fabric. 50k tow means there are 48-50,000 carbon filaments in the tow. Smaller tow i.e. 12k, 6k, 3k and 1k are obtained by dividing the 50k tow into smaller bundles.
Thread Count The number of threads (tow in carbon and yarn in Aramid) per inch. The first number will be the warp count and the second will be the fill count. Fill: The threads that run the width of the roll or bolt and perpendicular to the warp threads.
Warp The threads that run the length of the roll or bolt and perpendicular to the fill threads.
Finish The chemical treatment to fiberglass making it compatible with resin systems, therefore improving the bond between the fiber and the resin. Finishing fiberglass typically decreases the fiber strength by as much as 50%. Both Silane and Volanfinishes are epoxy compatible. Historically, Volan has been considered a softer finish for a more pliable fabric, but recent advances have yielded some excellent soft Silanefinishes.
Thickness Measured in fractions of an inch. The thicker the fabric the more resin required to fill the weave to obtain a smooth finished part.
Weaves

 PLAIN WEAVE

A very simple weave pattern and the most common style. The warp and fill yarns are interlaced over and under each other in alternating fashion. Plain weave provides good stability, porosity and the least yarn slippage for a given yarn count.

 2×2 TWILL WEAVETwill weave is more pliable than the plain weave and has better drivability while maintaining more fabric stability than a four or eight harness satin weave. The weave pattern is characterized by a diagonal rib created by one warp yarn floating over at least two filling yarns.  4-HARNESS SATIN WEAVEThe four-harness satin weave is more pliable than the plain weave and is easier to conform to curved surfaces typical in reinforced plastics. In this weave pattern there is a three by one interfacing where a filling yarn floats over three warp yarns and under one.

 8 HARNESS SATIN WEAVET

he eight-harness satin is similar to the four-harness satin except that one filling yarn floats over seven warp yarns and under one.This is the most pliable weave of standard fiberglass weaves and is used for forming over curved surfaces.

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Commercial Fiberglass-Fabric Weaver

Finishing Cross Reference & Resin Type Compatibility

RESIN COMPATIBILITY Burlington Industries Clark Schwebel J.P Stevens Uniglass Industries
Epoxy, Polyester VOLAN A VOLAN A VOLAN A VOLAN A
Epoxy, Polyester I-550 CS-550 S-550 UM-550
Phenolic, Melamine I-588 A1100 A1100 A1100
Epoxy, Polyimide I-589 Z6040 S-920 UM-675
Epoxy I-399 CS-272A S-935 UM-702
Epoxy CS-307 UM-718
Epoxy CS-344 UM-724
Silicone 112 112 n-pH (neutral pH) 
Satin Weave Style For Contoured Parts Fabricating

These styles of fabrics are one of the easiest fabrics to use and it is ideal for laying up cowls, fuselages, ducts and other contoured surfaces with minimal distortions.

The fabric is pliable and can comply with complex contours and spherical shapes. Because of its tight weave style,

satin weaves are typically used as the surface ply for heavier and coarser weaves.

This technique helps reduce fabric print through and requires less gel coat to create a smoother surface.

Satin Weave Type Conformity Unto Curved Shapes

Plain Weave Style for High Strength

Plain Weaves, Bi-axial, Unidirectional Styles For Directional High Strength Parts

Use this weave style cloth when high strength parts are desired.

It is ideal for reinforcement, mold making, aircraft and auto parts tooling, marine and other composite lightweight applications.

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