Preforming Process Spraying Method

The preparation of larger-volume preforms requires faster processes, such as the spraying technology of cut fiber bundles. In the spraying technology, a perforated metal mesh is made according to the shape of the preform, and a vacuum is applied to the back of the perforated mesh, and the reinforcing fiber is cut to the required length by a shredder, and the resin is sprayed. Then, by cutting off the air inlet pipe and blowing air, the fibers are dispersed and randomized, and directly enter the perforated mesh. The vacuum system on the back side of the perforated mesh makes the fibers firmly positioned in the mesh and makes the fibers contact each other. Once the required thickness of the reinforcement is reached, the power supply of the shredder is cut off, and the preform together with the perforated net is sent into the oven. The resin can be cured in the oven to shape the preform. Spraying technology produces large preforms at a very fast speed, that is, one preform per minute. However, cutting fiber bundles will affect the mechanical properties of composite products. In order to solve this problem, a new spraying technology that can spray continuous ring-shaped fiber bundles or continuous oriented fiber bundles has been developed.