Pultrusion is a continuous method of manufacturing various reinforced plastic shapes of uniform cross sections. Glass reinforcements, such as unidirectional rovings or multi-directional glass fiber mat, are guided through a liquid resin bath to thoroughly wet every fiber. The reinforcements are then guided and formed, or shaped, into the profile to be produced before entering a die. As the material progresses through the heated die, which is shaped to match the design profile, the resin changes from a liquid to a gel, and finally, into a cured, rigid plastic.
A pulling device grips the cured material and literally pulls the material through the die. Hence, the name pultrusion. It is the power source for the process. After the product passes through the puller, it is sawed into desired lengths. Although pultrusion is ideally suited for custom shapes, some standard products include rods, bars, angles, channels, and I-beams.