Wet filament winding is a widely used manufacturing process for producing hollow and closed end composite parts. Composite pipes, cylinders, pressure vessels and tanks are commonly produced with this manufacturing method. Wet filament winding involves saturating continuous fiber tows or rovings with a low viscosity resin which are wound directly on a rotating mandrel. There are many methods of applying resin to the reinforcement. The most widely used technique is to pass the fibers through a bath containing the low viscosity thermosetting resin but also resin film (rotating drum) distribution and dies are common. With any of these methods, a controlled band width of fiber is required before contact with the rotating mandrel. Process parameters including delivered fiber tension and winding rate are critical to part performance. These parameters as well as the wet-out of the fiber tow/rovings influence to a large extent the void content and fiber volume. After the part is wound, the mandrel may be rotated until the resin is sufficiently advanced or until gelation to provide uniform resin distribution and reduce drainage. This structure is then cured to produce the composite part and the mandrel is removed.
Wet filament winding resins are usually low viscosity two part resins but some may be single part or require elevated temperature to lower the viscosity. Winding is generally performed in the 700 cps to 3000 cps range but varies by equipment, operator, and part design. In general, thermosetting resin systems that are low viscosity at room temperature and have a long pot-life require time to stage (increase the viscosity) the resin. Although this may be required for manufacturing large parts, the overall process time may be more favorable if a faster gel system is used. An extensive range of filament winding resins are offered with a majority of products that can be processed at ambient temperature. Filament winding resins are offered for applications in sporting goods, cryogenic storage, aerospace, industrial, and many specialty areas.