Pultruded

Pultrusion is a continuous manufacturing process used to produce constant cross-section composite profiles with a high reinforcement content. Continuous fibers are saturated with a thermosetting resin and pulled through a heated die, where the resin cures and locks the fiber preform into a rigid profile. The resulting parts exhibit high strength and stiffness along the length, along with good dimensional stability and corrosion resistance, while remaining lightweight.

Process overview: Fibers such as glass, carbon, or aramid are drawn from supply packages and guided through a resin impregnation system. The impregnated fibers enter a shaping die that defines the cross-section and initiates curing. A puller retrieves the still-soft profile through the die and into an oven or furnace for curing, after which the solid profile is wound or cut to length. Materials are typically thermosetting resins (epoxy, polyester, vinyl ester); thermoplastic pultrusion is an emerging alternative.

Materials and properties: Common fibers include fiberglass and carbon fiber. Resin systems provide environmental resistance and electrical insulation in many applications. Pultruded products typically offer high strength-to-weight and stiffness-to-weight, excellent dimensional stability, and low moisture uptake, with good chemical resistance.

Limitations: Properties are highly anisotropic, strongest along the length and weaker in the transverse directions. The process is best suited to constant cross-section profiles, and complex geometries can be difficult or costly to realize. Tooling costs are high, and surface finish can require post-processing for some applications.

Applications: Pultruded profiles are widely used in construction (I-beams, channels, angles, rails), window and door frames, ladders, fencing, electrical insulators, and other structural components in demanding environments.