Rafter and Purlin Technical Information
Pultrusion is a manufacturing process for producing continuous lengths of fiberglass reinforced structural shapes. Raw materials include a liquid resin mixture (containing polyester resin, fillers and specialized additives) and reinforcing glass fibers.
The process involves pulling these raw materials (rather than pushing, as in the case of extrusion) through a heated steel forming die using a continuous pulling device.
The reinforcement materials are in continuous forms such as rolls of fiberglass mat or doffs of fiberglass roving.
As the reinforcements are saturated with the resin mixture ("wet out") in the resin impregnator and pulled through a die, the gelation (or hardening) of the resin is initiated by the heat from the die and a rigid, cured profile is formed that corresponds to the shape of the die.