Processes

Pultrusion is a continuous closed mold technique for making continuous lengths of products such as rods, angles, channels, I-beams, and tubes. The fiberglass reinforcements are usually a combination of continuous single end roving (Fiberex 408, 410 series or 503, 510 series), texturized roving (Fiberex TR series), and woven fabrics (Fiberex WR series). While continuous direct roving is always used in pultrusion, other forms of glass fiber reinforcements are used depending on the profile requirements of the end product. A surfacing veil of glass or polyester is normally used on the innermost and outermost layers to provide a resin rich surface and improved weatherability and aesthetics to the pultruded component. The reinforcements are impregnated with resin and pulled through a heated die whose cross section conforms to the profile of the end product. The glass fiber content in the finished product can vary from 55% to 80% of the weight depending on the combination and type of reinforcements used.