Composites have proved to be a worthy alternative to other conventional materials even in the high - pressure situations of chemical processing. Besides higher corrosion resistance, composite materials demonstrate good resistance to extreme temperatures, particularly in industrial settings.

The modification ability of composites for precise applications has been one of its advantages. The larger industry has now begun to acknowledge that these composites assure to offer tremendous business opportunities in an array of application.

Manufacturing Techniques

The end properties of a composite part are not only dependent upon the properties of fibre & resin matrix, but also depended on the way by which they are developed. There are ranges of processing techniques for fabricating composite parts or structures like resin transfer moulding (RTM), autoclave moulding, pultrusion and filament winding.

Out of these processes, filament winding is a cost-effective and efficient technique for manufacturing of fibre toughened cylindrical components and high-pressure pipes.

Process Technology

A large number of fibre rovings is pulled from series of creels into bath containing liquid resin, catalyst and other ingredients such as pigments and UV retardants. Fibre tension is controlled by the guides or scissor bars positioned between each creel and resin bath. Just before entering the resin bath, the rovings are usually gathered into a band by passing them through a textile thread board or stainless-steel comb. At the end of the resin tank, the resin-impregnated rovings are pulled through a wiping device that removes the surplus resin from the rovings and controls the resin coating thickness around each roving.

The most commonly used wiping device is a set of squeeze rollers in which the position of the top roller is accustomed to control the resin content as well as the tension in fibre rovings. Another technique for wiping the resin-impregnated rovings is to pull each roving separately through an orifice. The concluding method results in better control of resin content. Once the rovings have been meticulously impregnated and wiped, they are gathered together in a flat band and situated on the mandrel.

Band formation can be achieved by passing through a stainless-steel comb and later through the collecting eye. The transverse speed of the carriage and the winding speed of the mandrel are controlled to create the required winding angle patterns.

After winding, the filament wound mandrel is subjected to curing and post curing operations during which the mandrel is constantly rotated to maintain uniformity of resin content around the circumference. After curing, product is removed from the mandrel, either by hydraulic or mechanical extractor.

Materials Used

Glass fibre is the fibre most commonly used for filament winding, carbon and aramid fibres are also used. Most high strength critical aerospace structures are produced with epoxy or polyurethane resins, with epoxy, polyurethane or cheaper polyester resins being specified for most other applications. The ability to use continuous strengthening without any breaks or joins is a definite advantage, as is the high fibre volume fraction that is accessible, about 60% to 80%. Only the inner surface of a filament wound structure will be smooth except a secondary operation is performed on the outer surface. The component is generally cured at high temperature before removing the mandrel. Finishing operations such as machining or grinding are normally not required.


Related Tags: Cover Article