I'm currently doing an assignment and we have to come out with a manufacturing process. My group is planning to manufacture bicycle helmet by mixing coir fiber with epoxy resin and hardener but we can't seem to find a good way to manufacture it as the methods we found use too much time to manufacture one product. A detailed manufacturing way has to be included in the assignment. So I would like to ask is there any way to mass produce coir composite fiber ?
Any help will be much appreciated.
Thanks
Composite Manufacturing
The primary manufacturing methods used to produce composites include:
Manual Lay-Up
Automated Lay-Up
Spray-Up
Filament Winding
Pultrusion
Resin Transfer Molding
Manual lay-up involves cutting the reinforcement material to size using a variety of hand and power-operated devices. These cut pieces are then impregnated with wet matrix material, and laid over a mold surface that
has been coated with a release agent and then typically a resin gel-coat. The impregnated reinforcement material is then hand-rolled to ensure uniform distribution and to remove trapped air. More reinforcement
material is added until the required part thickness has been built-up. Manual lay-up can also be performed using preimpregnated reinforcement material, called 'prepreg'. The use of prepreg material eliminates
separate handling of the reinforcement and resin, and can improve part quality by providing more consistent control of reinforcement and resin contents. Prepreg must be kept refrigerated prior to use, however, to
prevent premature curing.
In spray-up, resin is sprayed onto a prepared mold surface using a specially designed spray gun. This gun simultaneously chops continuous reinforcement into suitable lengths as it sprays the resin.
After lay-up, the composite parts must be cured. Curing can take place at room temperature, often with heated air assist. Ovens, heated-platen presses, and autoclaves may also be used. Curing times may range
from a single hour to one-half day or longer. Curing is also accomplished with vacuum bag molding. Here a non-adhering plastic film, usually polyester, is sealed around the lay-up material and mold plate. A vacuum is
slowly created under the bag forcing it against the lay-up. This draws out entrapped air and excess resin. Vacuum bag molding is effective in producing large, complex shaped parts. Filament winding refers to wrapping a narrow fiber tow or band of tows of resin impregnated fiber around a mandrel of the shape to be produced. When the mandrel is removed, a hollow shape is the result. Uses for filament winding include pipe, tubing, pressure vessels, tanks and items of similar shape. Filament winding is typically applied using either hoop or helical winding. In hoop winding, the tow is almost perpendicular to the axis of the rotating mandrel. Each mandrel rotation advances the material-delivery supporting carriage one band width, butting the edge of one band next to the previous band. In helical winding, material is deposited in a helical path in one direction, then turns around on end and returns in a helical path in the opposite direction. Filament winding mandrels may be metallic or non-metallic and designed to either collapse to facilitate part removal or may be dissolvable after curing. Pultrusion is a continuous process used primarily to produce long, straight shapes of constant cross-section.
Pultrusion is similar to extrusion except that the composite material is pulled, rather than pushed, through a die. Pultrusions are produced using continuous reinforcing fibers called 'roving' that provide longitudinal
reinforcement, and transverse reinforcement in the form of mat or cloth materials. These reinforcements are resin impregnated by drawing through a resin wet-out station; and generally shaped within a guiding, or
preforming, system. They are then subsequently shaped and cured through a preheated die or set of dies.
Composite Materials & Manufacturing Fundamental Manufacturing Processes Study Guide, DV02PUB2 - 3 - Once cured, the pultrusion is saw-cut to length. Pultrusions can be hollow or solid, and applications include
bar and rod, pipe, tubing, ladder rails and rungs, and supports of many kinds.
Resin transfer molding or 'RTM' produces large, complex items such as bath and shower enclosures, cabinets, aircraft parts, and automotive components. In this process, a set of mold halves are loaded with
reinforcement material then clamped together. Resin is then pumped or gravity fed into the mold infusing the reinforcement material. Once the mold is filled with resin, it is plugged and allowed to cure. After curing, the
mold halves are separated and the part removed for final trimming and finishing.
please go to my paper , you will find more details.
best regards with best wishes
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