Patrick-Drinkwater – Page 2 – Carbon Kevlar Supply

TOW

TOW is a term used mostly for carbon fiber, meaning an untwisted bundle of continuous filaments.
TOW are groups (bundles) of carbon fiber filaments grouped together (3K TOW) means 3000 Filaments grouped together, 12K TOW is 12,000 filaments grouped together.
Each TOW group is then woven (interlaced / weaved) to form a fabric.
The higher the TOW the thicker the fabric will be.

Carbon fiber typically comes in the form of a woven fabric, which makes it easier to work with and can give additional structural strength depending on the application.
The most common are Plain and Twill weaves.
The tows are woven in an over/under pattern, offering tightly interlaced fibers which are highly stable.

Warp yarns (TOW’s) run vertically in carbon fiber weaving, up and down the long length of a fabric roll.
Weft yarns (TOW’s) run horizontally across the fabric roll.
The interlacing of these two types of yarns forms the fabric.
The warp yarns are held stationary in tension on a loom, while the weft yarns are drawn through the warp yarns.
The computers closely control and monitor the warp and weft yarns to ensure the right tension and strength is achieved for each weave

Carbon fiber fabric is often hemmed on it’s outer edges to keep fabric from fraying apart.
The nature of the Tow is that it is loosely held together and hemming helps keep the fabric together until an epoxy coating is applied.

Plain weave is interlaced one up and down Plain weave is the same as the front and back. The front and back of the twill are different. The plain weave is dense and thick.
Twill weave is two up and down or three up and down.
Twill structure is relatively soft compared to plain.

A plain weave carbon fiber sheet looks symmetrical with a small checkerboard style appearance. In this weave the tows are woven in an over/under pattern.
The short space between interlaces give the plain weave a high level of stability.
Fabrics stability is the ability for a fabric to maintain its weave angle and fiber orientation. (Not easily come apart)
Due to this high level of stability, plain is not well suited for layups with complex contours, it will not be as pliable as some of the other weaves.
Generally, plain weave fabrics are suited for flat sheets, tubes and 2D curves.

2×2 Twill Weave Carbon Fiber Pattern Is braid over-over-under-under
This pattern is elastic and is good for use with complex shapes because its weave is looser.

UNI, meaning one, all of the fibers are oriented in the same direction. This gives uni-directional (UD) fabric some high strength benefits.
UNI fabric is not woven, there aren’t any interlacing fibers with crimping that can weaken the structure.
One major drawback with UNI though is its workability. UNI tends to fall apart quite easily during the layup process since it has no interlaced fibers to hold it together.