What is Pultrusion
Pultrusion is a manufacturing process used to form a two-dimensional continuous profile fiberglass reinforced polymer (FRP). The pultrusion process allows for continuous processing of high-volume lengths of FRP profiles. The possibilities for simple to complex shapes is almost endless.
The Pultrusion Process
The process starts with creels of fiberglass unidirectional roving. These reinforcements provide strength along the longitudinal length of the finished pultrusion. As we move forward in the manufacturing process the next reinforcement in line is the continuous filament mat or CFM. CFM provided strength across the width or transverse direction of the finished pultrusion profile.
Both sets of fiberglass reinforcements are sent through a pre-form guidance card to begin the profile forming process. As the fiberglass gets closer to the resin bath, most profiles, are introduced to a synthetic surfacing veil. The veil is used to provide the finished profile with a high-quality surface finish as well as provide an additional layer of corrosion and weathering protection to the pultrusion.
Now that all of our Fiberglass and Veils are packaged together, they are introduced to either Polyester or Vinyl Ester resin. The resin bath is designed to completely saturate the fiberglass package. The resin consists of base Polyester or Vinyl ester, fillers, pigments, mold release, and catalyst. As the pultrusions continue to pull forward the resin and fiberglass is then formed into the shape through a set of custom machined CNC cards. These cards are carefully machined to the profile geometry, so the package can easily enter the pultrusion die.
At this point, the resin and fiberglass are then pulled into a heated pultrusion die. The resin and catalyst are heated to the specified temperature. Once we reach the specified temperature exothermic reaction happens turning the part from a liquid into a thermoset formed hard FRP profile.
The fully cured profile exiting the pultrusion die is advanced down the pultrusion line by a pair of dual reciprocating hydraulic puller clamping stations. These stations work in tandem hand over hand to create a continuous pulling action. The word pultrusion comes from this process of pulling and extrusion, thus the word pultrusion.
The last step in the manufacturing process is cutting. The pultrusion machine will keep an automatic count in lineal inches or lineal millimeters of the output after each cut. As the encoder records the output produced between cuts, once it records the set cut length, it will activate the saw to generate a new cut of the pultrusion being manufactured.
After the parts are cut, the operator will Quality inspect each manufactured pultrusion. If the part passes QC inspection the parts are palletized for shipment upon completion of the order.
To learn more, visit www.libertypultrusions.com