How Pultrusion Works: Manufacturing GRP Structural Profiles
Pultrusion is a continuous manufacturing process used to produce fiber-reinforced structural shapes with a constant cross-section — such as angles, channels, I-beams, H-beams and custom profiles.
The basic process
Continuous glass fiber reinforcement — including unidirectional glass fiber roving at the centre of the profile to carry longitudinal loads, and cross-reinforcing mats — is drawn ("pulled") through a resin bath and then through a heated die that cures the resin into a fixed shape. As standard, an isophthalic polyester resin is used for the matrix, though other resin types can be applied for special requirements.
Why the process matters for performance
Because the fiber orientation is controlled throughout the profile, pultruded GRP shapes achieve strong, consistent mechanical properties along their length — important for structural applications such as handrails, walkways, platforms and cable trays. A surface veil can also be incorporated to improve UV and wear resistance.
See the numbers
For published mechanical property ranges (tensile strength, flexural strength, compressive strength and more) for Union Fiber's pultruded profiles, see our guide to reading a GRP mechanical datasheet or the technical data table on our GRP Pultruded Profiles product page.