The spray lay-up technique can be said to be an extension of the hand lay-up method. In this technique, a spray gun is used to spray pressurized resin and reinforcement which is in the form of chopped fibers.
Generally, glass roving is used as a reinforcement which passes through spray gun where it is chopped with a chopper gun.
Matrix material and reinforcement may be sprayed simultaneously or separately one after one.
Spray release gel is applied on to the mold surface to facilitate the easy removal of component from the mold.
A roller is rolled over the sprayed material to remove air trapped into the lay-ups. After spraying fiber and resin to required thickness, curing of the product is done either at room temperature or at elevated temperature.
After curing, mold is opened and the developed composite part is taken out and further processed further. The time of curing depends on type of polymer used for composite processing.
The schematic of the spray lay-up process is shown below:
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