Question

Briefly describe one of the method of incorporating fibers into matrix (i.e. fiber reenforced composite manufacturing method).

 

Answer 1

 

There are basically 2 categories for incorporating fibers into the matrix.

First is when fibers and matrices are processed directly into the finished products. Processes are filament winding and pultrusion

In second, fibers are incorporated into the matrix to prepare ready-to-mould sheets which are stored and processed later when required to form laminated structures by autoclave moulding or compression moulding.

 

Pultrusion is one of the continuous automated closed molding, composite processing method.The basic mechanism of putrusion system is same as that of the metal extrusion process.The
only difference is that in extrusion process, material is pushed through the dies whereas in
pultrusion, material is pulled through the dies.

In the above figure, there is continuous roll of reinforced fibers at point 1. And then, comes Tension roller at 2. Resin is impregenated at point 3 and then resin soaked fiber comes out of 4. Die and heat source is depicted by 5 from which through pull mechanism (6) finsihed hardened fiber reinforced polymer comes out.

In resin
tank, fibers are dipped thoroughly to get completely wetted fibers. Now, these resin saturated
fibers are guided to the hot die where the desired profile is given to these resin impregnated
fibers with the help of dies. Curing of the composite also takes place in this section due to
heating. Finally, putruded profiles are cut with the help of a cutter which is inbuilt after the
pulling mechanism in the putrusion system

Advantages:
1. Low cost automated system where least effort is required and produces high quality products.
2. Products have good surface finish
3. Due to continuous production, production rate is quite high. 4. Less Maintenance is required.

Disadvantages: 1. this process is limited to constant cross sectional areas.
2. fiber orientation control is not possible.
3. Thin wall parts are very difficult to be produced.

Application:
1. In the production of solid rods, tubing, and long flat sheets are easily fabricated with pultrusion
process.
2. Cross sectional structural sections with simple sections such as channels, angled and
flanged beams.
3. In making tool handles for high voltage work and rail covers for subways.