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Wednesday, February 26, 2014

Advantages and Disadvantages of Filament Winding Process

The most important advantage of filament-winding is its low cost, which is less than the prepreg cost for most composites. The reduced costs are possible in filament-winding because a relatively expensive fiber can be combined with an inexpensive resin to yield a relatively inexpensive composite. Also, cost reductions accrue because of the high speed of fiber lay-down. Other advantages of filament-winding compared to other compacting and curing processes are:

Highly repetitive and accurate fiber placement (from part to part and from layer to layer). The accuracy can be superior to that of fiber placement and automated tape-laying machines.
The capacity to use continuous fibers over the whole component area (without joints) and to orient fibers easily in the load direction. This simplifies the fabrication of structures such as aircraft fuselages and reduces numbers of joints for increased reliability and lower costs.
Elimination of the capital expense (and size restrictions) of an autoclave and the recurring expense for inert gas. Thick-walled structures can be built that are larger than any autoclave can accommodate.
Ability to manufacture a composite with high fiber volume
Mandrel costs can be lower than other tooling costs because there is usually only one tool, the male mandrel, that sets the inside diameter and the inner surface finish.
Lower cost for large numbers of components because there can be less labor than many other processes. It is possible to filament wind multiple small components, such as up to 20 golf shafts at once (Fig. 8), leading to sharply reduced costs compared to flag rolling. Costs are eliminated for bagging and disassembly of the bagging materials, as well as the recurring costs of these materials.
Costs are relatively low for material since fiber and resin can be used in their lowest cost form rather than as prepreg.

Disadvantages

Need for mandrel, which can be complex or expensive
Necessity for a component shape that permits mandrel removal. Long, tubular mandrels generally do not have a taper. Unless nonuniform shapes are capable of mechanical disassembly, mandrels must be made from a dissolvable or frangible material. Different mandrel materials, because of differing thermal expansion and differing composite materials and laminate lay-up percentages of hoops versus helical plies, will demonstrate varying amounts of difficulty in removal of the part from the mandrel.
Difficulty in winding reverse curvature
Inability to change fiber path easily (in one lamina)
Poor external surface finish, which may hamper aerodynamics or aesthetics.

It is important to note that most of the disadvantages are application-specific and, in many cases, have been circumvented by innovative design and equipment modifications.

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