Types / weight of fabric?
All types of carbon are sold as either a fabric, tape or straight tow (long strands of fibres). The fabrics are usually woven with strands laid in two perpendicular directions (warp and weft) with various weave patterns (commonly plain weave or 2 x 2 twill), or strands aligned in one direction, known as Uni-Directional (or ‘UD’). Woven fabric or UD material can incorporate fibres of different weights, which is usually expressed as grams per square metre. For example the most commonly available fabric is a 200gsm 2x2 twill weave.
Using uni-directional fibres can offer an advantage in some applications because the designer is better able to control the location and orientation of fibres in the final part. For example, if a part required twice the number of fibres in one direction than in its perpendicular direction, using a woven fabric would add more fibres in the perpendicular direction than is necessary. This would add (unnecessary) strength, but also additional weight. UD fibres also benefit from being laid ‘flat’ on a microscopic level, compared to woven fibres which need to kink slightly to accommodate the weave pattern.