What is the Pultrusion Manufacturing Method?
Pultrusion is a continuous composite manufacturing process that utilises fibre reinforcements and resin matrices to produce cross-sectional materials. It is typically used to produce fibre-reinforced plastics, also known as fibre-reinforced polymers (FRP).
Composites made through pultrusion are popular for many reasons, namely the cost-effectiveness nature of their process in fabricating structural composite profiles. In addition, pultrusion composites are known for having:
- Excellent structural strength
- High uniformity
- Corrosion resistance
- Low weight
- A low number of manufacturing defects
- Electrical non-conductivity
Where Can Pultrustion Composites Be Used?
Composites made through pultrusion are commonly used in the:
- Aerospace industry – structural components of aircraft.
- Construction industry – PVC windows, glass-fibre reinforcement, profiles.
- Automotive industry – structural parts of the vehicle body.
- Sports industry – ski poles, golf course flagsticks, tent poles.
The Pultrusion Process
The pultrusion process is comprised of a few steps, as explained below:
- Raw materials (glass, carbon or aramid) are fed into the infeed area. These can be in a roving/tow, mat, woven or stitched format – with the roving format being the most common.
- The materials are impregnated with a resin matrix. Common resins include polyester, vinylester, epoxy or phenolic.
- The impregnated reinforcement is then pulled into a heated pool where they are passed through a heated pultrusion die. Here, the cross-linking process begins, with the resin matrix drying and curing. Maintaining optimum temperature is vital at this stage to ensure the resin pulls away from the die naturally.
- The die is separated from the cured profile using a pulling mechanism, after it is cooled, often using a reciprocating hydraulic clump puller. The profile is then sawed off to the required length, ready to be processed further.
Top Resins for Pultrusion Composite Manufacturing
Various resin types can be used in the pultrusion process, including polyester, polyurethane, vinylester and epoxy.
Epoxy resins provide various advantages over other types, such as:
- Low shrinkage rate – allowing their cure rate to be controlled using hardeners.
- Great thermochemical integrity – ideal for reinforcing and bonding FRP components.
- High corrosion resistance
- High performance at high temperatures
- Excellent electrical properties
Araldite® LY 556 / Aradur® 917-1 / Accelerator DY 070
Araldite LY 557 / Aradur 917 / Accelerator 070 is an epoxy composite moulding system that is recommended for pultrusion composite processes. It is an anhydride-cured standard matrix system with an extremely long pot-life and low viscosity.
Araldite® LY 1135-1 / Aradur® 917-1 / Accelerator 960-1
Araldite LY 1135-1/Aradur 917-1/Accelerator 960-1 is an epoxy latent anhydride curing system that can be used for pultrusion composite processes. The combination of the hardeners can be easily mixed to adjust the reactivity. The system exhibits excellent mechanical, dynamic and thermal properties, providing excellent chemical resistance at temperatures of up to 80° C.
Araldite® LY 3585 / Aradur® 3475
Araldite LY 3585 / Aradur 3475 is an epoxy composite moulding system that can be used for pultrusion manufacturing. It is a fast-curing system that is suitable for composite mass manufacturing.
For personalised advice on which resins to use for your pultrusion composite manufacturing, get in touch with one of our technical experts.