Pultrusion is the continuous processing of raw materials by ‘pulling’ (rather than ‘pushing’, as is the case in extrusion) resin-rich glass rovings through a heated steel die to form profiles (shapes) of constant cross sections of continuous lengths. Glass roving and fiberglass mats provide strength and stiffness. Resin provides shape and protects the fibers from corrosion. Engineers can modify the physical and chemical characteristics by specifying different formulations or proportions of these materials.

• Glass roving begins the process: Multiple strands guided into parallel bundles that run along the length of the profile.
• Fiberglass mat added for multidirectional reinforcement.
• Glass reinforcements are “wet-out” with a thermoset resin, (Ex: Polyester, Vinyl Ester, etc.)
• Surfacing veil added to enhance surface appearance and of final product.
• Curing of the composite: Hardening occurs while the wet-out reinforcements are being pulled through the heated die.
• Puller moves product to cut-off saw where desired length is cut.

A solid, rigid profile with all reinforcements laminated within, is the result.

Pultruded Grating Manufacturing Process Diagram