Structural Pultrusion Process

The pultrusion process is ideally suited for the manufacture of structural shapes. Analogous to the steel rolling process, this process allows structural shapes to be manufactured to length, only restricted by transportation limitations.

Continuous glass fibers that enter the process on the left are actually pulled the length of the process by a tractor (illustrated) or hand-over-hand pullers shown on the right. During the process, the glass bundle of continuous strands is wrapped with continuous strand mats that will provide the transverse strength. The entire reinforcement bundle is then pulled into a liquid resin bath (polyester or vinyl ester) and “wetted” out. The wetted reinforcement package is wrapped in a surfacing veil, which allows a resin-rich finish on the part, offering a first barrier to corrosion and a smooth finish. The completed package then goes into a performer that roughly forms the package into the appropriate shape to enter the heated die for curing. The die is the exact shape of the final part desired. Upon exiting the die, the part is over 90% cured and solid. The length of the part required is pulled through the cutoff saw and the process is complete.