What is filament winding?

Resin impregnated fibres are wound onto a rotating mandrel which can be cylindrical, conical, or spherical in shape. Other mandrels of more complex cross sections can also be used providing the general shape is convex in nature. The fibres are fed through a resin bath and the feeding mechanism traverses the length of the mandrel. The layers of fibre are applied to form the required thickness of the laminate. The mandrel rotating speed and the traversing speed dictate the fibre winding angle. The cure process is generally initiated once the winding is complete either by heating the mandrel while it is still on the machine or by removing it and placing the part in an oven.

The typical fibre, especially for pipe work, is glass fibre in the form of roving or woven tapes. Graphite and Aramid in the form of roving, yarns or woven tapes can be used if the application requires these fibres.

This method is fast and economic and has moderately accurate control of the resin content. These factors have made filament winding the preferred method for manufacturing pipes for the utilities and oil and gas industries. The capital equipment cost for the mandrel is high. The inner surface is often the surface in contact with the transport medium, hence the mandrel serves to give a high quality finish. However, the outside surface, usually the visible surface, is not moulded.

Some of the key points of this method include: