Pultrusion is an eco-friendly manufacturing option, producing significantly fewer pollutants than many alternatives. It is also cost-effective and highly efficient, giving it widespread appeal. The pultrusion manufacturing process consists of the following four steps:
The pultrusion process involves pulling the fiber reinforcement through a heated die. These materials are typically either continuous strand mats or rolls of filament (otherwise known as rovings). The first step of this process is feeding these raw materials into the pre-forming guide. This must be done very carefully, as inaccuracy can have a negative impact on the final profile. There a large number of fiber inputs coming together to create the part. A tension roller within the guide shapes the materials.
Once brought together in the guide, the reinforced fibers undergo resin impregnation. Traditionally this is done by moving the fibers through a wet-out bath of polymer. The wet-out baths typically consist of a resin, pigments, fillers, and a curing catalyst. In some cases, the resin is injected into the heated die.
After passing through the wet-out bath, the reinforced fibers pass through a heated die. This is the step where the fibers begin to solidify into their final shape, as the heat initiates the cross-linking process within the impregnated reinforcements. A key consideration during this step is the temperature. A low temperature can result in a weak composite profile, while a temperature that is too high can cause the composite to crack.
Near the end of the heating process, the temperature of the resin will become higher than the temperature of the die. This begins the separation process. Manufacturers use a pulling mechanism to remove the cured profile from the die. Once separated, the profiles can be cut to the appropriate lengths and undergo secondary processing if necessary.
High strength-to-weight ratio. In pound-for-pound comparisons, this material is stronger than steel but is more lightweight, making it easier to work with and less expensive to transport.
Durability. Pultruded FRP composites are very durable, making them suitable for use in various heavy-duty applications.
Corrosion resistance. Its corrosion resistance allows FRP to withstand chemicals, water, salt, and other harsh conditions, making it extremely long-lasting and low-maintenance.