Composites Explained: The pultrusion process

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Pultrusion is a manufacturing technology for producing continuous lengths of fiber-reinforced polymer composites of consistent quality at an excellent price point. A composite is created by the process of combining two or more materials to make them stronger than if they were used by themselves. Manufacturing composites using the pultrusion process creates a constant cross-section of fibers providing increased strength and lasting durability. The flexible process allows for a range of chemical and technological variations.

GFRP (glass fiber-reinforced polymer) composites are versatile materials that can be shaped, drilled, pigmented, and finished to varying degrees. More than 70% of our products are supplied into customer applications as critical components.

How the pultrusion process works

Pultrusion is an automated process for the continuous production of fiber-reinforced profiles with a constant cross-section. The manufacturing process begins with the fibers (glass, aramid, carbon, or basalt) being pulled into an impregnation bath.

Once the raw fiber has been impregnated with liquid resin (polyester, vinyl ester, polyurethane, epoxy, hybrid resins) it is pulled further into a forming and curing die (mold) where it is heated and given its final shape. The material, now reinforced and cured, is continuously and automatically pulled through a flying cut-off saw which cuts the profiles to the desired length.

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Advantages of the pultrusion process

  • The process is faster and more economical than ever before. This has made mass production more efficient and has bought down the cost of manufacturing making it cost-efficient for the consumer.
  • Resin content in a profile can be accurately controlled to meet the customized properties of a profile. Consistent quality and specification of composite profiles can be achieved with strict tolerances.
  • The manufacturing process is a low-energy process requiring no water and minimal power.

GFRP composites have a tensile strength greater than structural steel on a kg-for-kg basis. Combined with load-specific properties, it is a technically preferred material for industries including construction, recreation, and utilities. 

It is 1/4 the density of steel and it is 30% less dense than aluminum. GFRP composites are versatile and offer many advantages.