Fiberglass Backing

Stage 1: Preforming

Before the glass fibers can be impregnated and reinforced by the resin matrix, they must first be preformed and fitted into the pultrusion machine. To do this, large coils of rovings are pulled through a preformer of tension rollers that get the filaments into a workable shape. In this stage of fiberglass manufacture, the accuracy and continuity of the roving guide are necessary to achieve the strength and quality known of fiberglass.

Stage 2: Resin Bath

In this stage, the preformed filament rovings (or mats) are saturated in a wet-out resin bath that acts to impregnate the glass fibers with the performance properties required of the specific project. The composition of the resin bath will change depending on the performance properties required of the finished product, so it’s worth talking to a pultrusion expert to get an understanding of which resin matrix will work best for your project.

Stage 3: Heated Die

Once impregnated, the glass fibers are then pulled through a heated pool where they are cast and set into the desired molds. The heated pool works to activate the catalyst within the resin and begin polymerizing the product. It’s an exothermic reaction, so it relies on a constant temperature and once initiated, the temperature of the resin will exceed that of the die.

Stage 4: Finished Product

Once the pultrusion process is complete, all that needs to be done is to separate the fiberglass from the die and, if needed, to cut the product to size. When curing, the fiberglass naturally pulls away from the die so separating the composite and the die doesn’t require too much finessing. However, to ensure complete separation of die and product, a hydraulic clump puller is used.