Australian-made Towpreg is now available.
Filament winding, the process of winding filaments under tension over a rotating mandrel, is a technique primarily used to manufacture hollow, circular, or prismatic parts such as pipes and tanks. This process involves wrapping continuous filaments, such as carbon or glass fibres, around a rotating mandrel in a precise pattern. The conventional wet-winding method involves dragging composite fibres through an open resin bath. However, technological advancements have introduced an alternative approach known as Towpreg.
Towpreg is the fruit of the CST development team, bringing decades of experience in R&D and innovation in filament winding processes to this unique development. According to the team, their impregnation process is more uniform and consistent than the bath method, leading to improved product quality and performance and ensuring predictable mechanical properties and reliability.
The company’s founder, Clive Watts, explained: “We’ve found that the winding speed over the mandrel can be significantly increased with Towpreg, allowing for multi-spindle winding machines. Additional speed and efficiency increase productivity, reducing manufacturing time. It’s exciting to have precise control over resin and fibre volumes so that we can customise material properties for controlled, specific performance requirements.”

The Advantages of Towpreg
- Increased Winding Speed:
Towpreg enables faster winding speeds and facilitates the use of multi-spindle winding machines. This efficiency translates to enhanced productivity and reduced manufacturing time.
- Consistent Resin Impregnation:
With Towpreg, resin impregnation is more uniform and consistent across the fibres, improving product quality and performance. This consistency ensures predictable mechanical properties and enhances the reliability of the final product.
- Control Over Resin and Fibre Volume:
When using Towpreg, manufacturers can exercise greater control over the resin and fibre volume in the composite structure. This control allows for precise customisation of material properties to meet specific performance requirements.
- Fibre Bandwidth Consistency:
Towpreg bandwidth can be monitored and controlled during production to ensure a lower coefficient of variation. This means products can be made with a tighter design tolerance, leading to potential savings from lower mass, weight, and wall thicknesses.
- Safer Work Environment:
Towpreg minimises exposure to hazardous fumes and chemicals associated with traditional wet-winding processes and removes the fire risk from exothermic reactions in resin baths. The enclosed nature of Towpreg manufacturing reduces health and safety risks for operators, creating a safer working environment.
- Potential for Automation:
The use of Towpreg opens up opportunities for automation and robotics in filament winding operations. Robotic systems can be employed for precise handling and placement of Towpreg materials, further enhancing efficiency and repeatability.
CST’s Innovative Towpreg Solutions: Through extensive research and development, CST has established itself as a leader in Towpreg manufacturing. Leveraging years of experience and expertise, CST has developed proprietary resin formulations tailored to different fibre types, ensuring the best possible impregnation and performance. Additionally, CST has designed and constructed specialised machines for Towpreg manufacture, incorporating advanced resin impregnation techniques and closed-loop feedback and control systems.
Looking Ahead: CST’s achievements in Towpreg manufacturing have paved the way for new opportunities, including using Towpreg in pressure vessel applications.

Conclusion: The adoption of Towpreg represents a significant advancement in composite filament winding technology, offering numerous advantages over traditional wet-winding methods. CST’s dedication to developing high-quality Towpreg solutions has positioned it as a leader in the industry, driving efficiency, safety, and performance in composite manufacturing processes.