Filament winding is a one of the processes for the production of composite materials from fibrous reinforcements and thermosetting polymers. The fibre coils are mounted on tensioning unit axles. It ensures proper tightening of the fibres during the filamend winding process. The fibres unwind from the tensioning unit and pass through a bath with an impregnating mixture against the delivery arm of the filament winding machine and forward to a filament winding mandrel. The filament winding mandrel is the basis on which the reinforcements are coiled up. In most cases, the mandrel is made of metal.
The mandrel rotates, and the delivery arm moves along the rotating mandrel and places fibres on the mandrel at a suitable angle. Filament windingmachines are computer controlled and allow the accurate and repeatable placement of fibres. After the filament winding procedure is finished, the mandrel with the coil is transferred into a curing oven in which the impregnating mixture is crosslinked and hardened. After hardening, the filamend winding is taken off the mandrel using a hydraulic device for detachment
The fibrous reinforcements, which are used for coiled products, are usually in the form of continuous fibre coils on paper tubes. The paper tubes are necessary to reach a suitable tightness of the fibres during filamend winding through them and through the tensioning unit axles. Sometimes, reinforcements in other forms are added, such as fleeces and fabrics. Most commonly used are reinforcements from glass fibres. However, reinforcements from other types of fibres are also used. We use mostly E glass fibres.
Impregnating mixtures are composed of thermosetting resins and initiators. Occasionally, mixtures with other additives are used. We are currently using exclusively epoxy resins for filament winding.
The internal dimensions of the coiled products range from two centimetres to twenty-five centimetres. The wall thickness usually ranges from a few millimetres to a few centimetres. Coiled products can be manufactured in lengths of up to four metres. Coils have a smooth inner surface with small tolerances, while the external surface is coarser with larger tolerances.
If a smooth external surface and small dimension tolerances of the external diameter are required, the external surface can be processed by centreless grinding or turning. The mechanical properties of the coiled products depend on the angle of the fibre filamend winding. In filament winding, the angle of the filament winding may change by layers.
Coiled products made of glass fibre and epoxy resins have good electrical insulation properties. Numerous coiled products are used in the electrical industry. Filament winding is a suitable technology for the production of pressure vessels and pressure pipes. Numerous coiled products are also used in the nautics industry. Coiled products are used in many other fields as well.
Similarly to pultrusion, the filament winding technology started in our company or in the legal precursors of the company in the mid 60s and switched from mainly dedicated production to other areas.
