What is Pultrusion?

Pultrusion is a method of manufacturing that refers to a continuous process that utilizes fiber reinforcements and resin matrices to produce constant cross-sectional profiles.

Below are the links to navigate quickly to the key sections

  1. History

  2. Manufacturing process

  3. Feed Raw Materials into the Guide

  4. Impregnate the Fiber in Resin Bath

  5. Go Into the Heating/Curing

  6. Separate

  7. Summary


A man named Brant Goldsworthy invented the pultrusion process, and he was a major figure in the invention and development of composite material technology.

He came up with the idea of combining various materials together to make stronger plastics while working for an aircraft company that was supplying items for the US Army during the Second World War.

His creations were so successful that he eventually decided to open his own company, where he made several advancements in the field of composites and created certain plastics that were generally stronger than anything previously seen.

Manufacturing Process

Pultrusion refers to a manufacturing process in which continuous lengths of fiberglass reinforced polymers with a constant cross-section are produced.

During this process, reinforced fibers, liquid pultrusion resins, pigments, and other raw materials are normally pulled through a heated die, converting them into FRP composite products.

Step 1: Feed Raw Materials into the Guide

The pultrusion process involves pulling the necessary raw materials through a heated die, which means that the reinforced fibers need to be in continuous form.

In most cases, either roll of filaments known as rovings or continuous strand mats is used. They provide the tensile strength required to pull the rest of the fiber reinforcements through the die.

That said, the first pultrusion process step involves feeding the continuous roving filaments or mats into the machinery through the performing guides. In the guide, the roving filaments are often pass through a tensioner, then shaped into the finished profile.

It is, therefore, vital that the manufacturer maintains utmost accuracy when feeding the rovings in the guides, as this determines both the strength and the quality of the resulting profile.

Step 2: Impregnate the Fiber in Resin Bath

The reinforced rovings or mats go through a wet-out bath for resin impregnation. The forming guides are placed before, within, or after this resin bath.

The wet-out bath usually contains a resin, most commonly polyester or vinyl ester, pigments, fillers, and also a catalyst to help in curing. It's critical to note that there are different types of wet-out baths.