Characteristics and requirements of spray up forming method

^{1. Characteristics of spray up forming method}

 (1) use mechanization to replace the raw material supply system of hand paste method, that is, the curing agent, accelerator, resin and so on through different pipes in the spray gun mixed directly into the mold, and made of products.  The curing agent at this time should be liquid curing agent M.

 (2) It can be sprayed together with short-cut untwisted roving, or it can be sprayed with resin on glass fiber fabric separately, and then bubble FRP products.

 (3) It can also be used for spraying gelcoat resin, instead of manual brushing.

 (4) Save materials and improve efficiency.

 (5) This method is not suitable for the production of small products.

 ^{2. What are the requirements of spray molding}

 (1) Requirements of no-twist roving: good cutting, no static electricity, good permeability, easy to defoam, good demolstering, good dispersity.

 (2) Requirements for resin: hardening time and viscosity should be moderate, with thixotropy.  When red or black gelcoat is used, curing agent and accelerator can be increased by 10%.

 (3) The type of jet, power and pressure of air compressor should be selected appropriately.

 (4) Injection volume.  According to the needs of FRP products to determine the amount of glue, and then determine the amount of injection, in Japan, generally 500 ~600 g /m2.

 (5) When spraying gelcoat, it should be carried out continuously. If it stops for more than 20 minutes, it will wrinkle between two times.