Carbon Fiber's Improved Filament Winding Makes a Difference

1. Carbon Fiber's Improved Filament Winding Makes a Difference Filament winding is one of the oldest processes for fabricating carbon fiber parts. It is a process that pretty much remained static until about 10 years ago, when incremental changes began improving it quite a bit. The current state of filament winding it such that it is having a measurable impact on how carbon fiber is utilized. If you are not familiar with filament winding, it's a process that resembles large-scale weaving – at least visually. Large rolls of carbon fiber filament are loaded onto spools and threaded through a winding machine. The filament is then picked up and wound around a rotating mandrel. Depending on the number of filaments and their relative positions, they can be wound around the mandrel in any number of patterns. This creates a continuous form that can be divided into pieces of varying lengths. The Early Days of Filament Winding Filament winding was first used as a manufacturing process in the years immediately following World War II, according to Composite World's Ginger Gardiner. Manufacturers utilized the process to create solid rocket motor cases. Light poles, pressure vessels, and pipes – all reinforced with carbon fiber – made their way to market in the 1960s and 70s. The process back then was always the same. The filament was bathed in an epoxy resin just prior to being wound around the mandrel. Completely wound product was fed into a high-temperature autoclave that would cure the resin, creating a strong and durable material reinforced with carbon fiber filaments. This process is known as wet winding. It is a process still used today. A number of years ago, new methods were developed to replace wet winding. Engineers figured out how to use dry fibers in concert with liquid molding processes. They also developed processes using towpregs and prepregs. All of these new processes eliminated the need to bathe filament in epoxy prior to winding.

2. Today's Filament Winding Today, filament winding can look remarkably different compared to its first-generation predecessor. For example, our industry is now utilizing high-speed filament winding capable of creating complex parts with variable cross-sections and unusual shapes. We are no longer limited to static, cylindrical mandrels that produce only tubes of varying sizes. Robotics are also being introduced to filament winding. Robotic systems make the entire filament winding process faster and more efficient by eliminating the inefficiencies of human involvement. It is also making filament winding a cheaper process without sacrificing quality. Even 3D printing is having an impact on filament winding. According to Gardiner, there is a company in Stuttgart, Germany that has figured out a way to combine a robotic wet winding process with 3D printing to create finished products that marry carbon fiber/epoxy products with composite or metal cores. The process can even be modified to create finished products that have no core. New Shapes and Sizes The net benefit of all these new technologies is that we are able to create composite parts in all shapes and sizes while still taking advantage of filament winding. Why does this matter? Because filament winding can be automated to a much greater degree than traditional layups. By improving filament winding processes to accommodate so many shapes and sizes, we keep the speed and efficiency without sacrificing design flexibility. We are excited to see how technology is changing our industry. We don't know what filament winding will look like 10 years from now, but we think it's a safe bet that things will be even better than they are today. That's good for both our industry and customers alike.