When manufacturing composites, there is a wide range of choices when selecting the fiber reinforcement and the construction of the reinforcement. First, one must select the fiber to be used. It could be fiberglass, carbon fiber, aramid, basalt, etc.
Depending on the composite product being manufactured, the fiber being used and the construction of that fiber can be easily decided. For example, one wouldn't use expensive carbon fiber cloth to make a bath tub. Although it would be awesome, the added strength would not be necessary, and generally, it is not important that a bath tub be lightweight.
Once the fiber is determined, the construction of the fiber must also be selected. The construction of the reinforcing fiber will be dictated by the manufacturing process and the end requirements. Below are some of the commonly used fabrics in composite material manufacturing.
Chopped Strand Mat
Chopped strand mat is a fabric reinforcement and is most commonly manufactured with fiberglass. Short discontinuous fibers are randomly spread, and held together with a binder. Common weights of chopped strand mat are:
- .75 oz/sqyrd
- 1 oz/sqyrd
- 1.5 oz/sqyrd
- 2 oz/sqyrd
- 3 oz/sqyard
Chopped strand mat is an inexpensive way to add bulk and thickness to a composite product. Although chopped strand mat is not structural, it is very easy to work with and economical.
Manufacturers of chopped strand mat include:
Continuous Strand Mat
Continuous strand mat is a fiberglass fabric that is more structural then chopped strand, but more expensive. Continuous strand mat is manufactured by laying filaments of glass in a circular pattern, and holding the fibers together with a binder.
Continuous strand mat is commonly used in pultrusion to add cross-directional strength to pultruded profiles.
Manufacturers of continuous strand mat include:
Woven fabrics can be manufactured from most any reinforcement, and the technology comes directly from the traditional textile industry. Here, the composite reinforcement is woven together in a wide variety weave patterns and weights.
Woven fabrics provide excellent structure to composite products and absorb resins extremely well. Reinforcements that are woven are used in a wide variety of manufacturing processes including hand layup, vacuum infusion, compression molding, and pultrusion.
One highly desirable feature of woven composite fabrics is their ability to be highly drapable and conformable. This is important when laminating composite products such as surfboards or after-market automotive parts.
Manufacturers of woven fabrics (weavers) include:
Knitted or Stitched Fabrics
Layers of reinforcement can also be stitched together in layers to create a composite fabric. Any type of fiber can be used as the reinforcement, and any combination is possible. This type of fabric is known as "knitted" or "stitched."
Stitched fabrics are extremely versatile. This is because a wide range of fiber inputs can be used in any combination. (Hybrid Fabrics) Additionally, the direction of the reinforcing fiber can be specifically tailored for the application.
For example, many ski and snowboard manufacturers use "hybrid" stitched fabrics where there is carbon fiber running in the "zero direction", from nose to tail of the ski, and fiberglass is used in the 90 degree (rail to rail), and in the +/-45 degree direction, to provide torsion strength.
Manufacturers of stitched fabrics include:
Surfacing veils are often used in composites. A veil is a non-woven thin fabric that is usually made of polyester, but fiberglass and nylon are used as well. Veil materials are commonly used in other industries besides composites. For example, picture the thin fabric on the bottom of your couch or your box spring. This is exactly what a non-woven veil is like.
In composites, surfacing veils are used on the exterior of the part to help absorb resin and provide a resin rich layer which can help protect the composite from UV, corrosion, and water absorption.
Manufacturers of surfacing veils include: