Filament Winding: Everything You Need to Know
Filament winding is a process used to create cylindrical components or vessels. Filament winding machines are used to create a varied range of products including pipes and pipe joints, cylinders of all sizes, drive shafts, masts, pressure vessels, storage tanks and chemical containers. It is a relatively simple mechanised process that involves winding a filament, or fibre, around a cylindrical mandrel. The filaments are usually treated with resin before being wound and are then "cured", or heated, afterward.
How do filament winding machines work?
A filament winding machine consists of the rotating mandrel and the carriage that moves along its axis and continuously pays out the fibre. There is no break in the fibre, so the resulting laminate is very strong. The simplest filament winding machines consist of two axes and are best suited for the manufacture of pipes only. More complicated machines can consist of four or even six axes and allow for the manufacture of closed cylinders and other convex shapes.
As the carriage moves along the length of the mandrel, it pays out fibre (or filament) that has usually been soaked in resin. Once the desired amount of filament has been wound, the vessel is heat-treated and is then ready to use. The mandrel itself can be removed and used again, or it can form the interior surface of the vessel.
What materials does a filament winding machine use?
The most common fibres used in filament winding are glass or carbon, although boron and aramid fibres are also used. They are used straight from a creel and not woven or stitched into fabric form before use, which keeps manufacturing costs down.
Many different kinds of resins can be used to impregnate the fibre before it is wound, including epoxy, polyurethane, vinylester and polyimides. The finished result is usually a strong, light, stiff material suitable for a range of uses.
What are the advantages of the filament winding process?
The filament winding process is an easily automated process. The machinery is quite simple and therefore requires a minimum level of staffing, although the more complicated machines with four or six axes are computer-controlled and therefore need to be programmed. The fibre cost is minimal because the fibre does not need to be woven or stitched prior to use. The resulting laminates are strong and heat-resistant.
What are the disadvantages of the filament winding process?
The process is only used for convex components or products. The resins used need to be low-viscosity resins and these are less safe in terms of health and safety. Also, the mandrels for large components can be quite costly.
What is the finished product?
The finished product can be light, strong open or closed ended cylinders that can be used in a wide variety of ways. These include pipes for sewage, water and gas; oxygen cylinders; firefighters' and scuba divers' breathing equipment; bicycle forks and rims; golf clubs; and rowing oars. Masts for ocean-going yachts are manufactured using the filament winding process, as are power and transmission poles and even lamp posts.