Reaction injection molding (abbreviated ?RIM), an industrial molding process.
There is a chemical reaction in the molding process of an injection molding method, the raw material used in this method is not a polymer, but two or more liquid monomers or pre-polymers, in a certain proportion to the mixing head were added to the mixing head, mixed under pressure, and then injected immediately into a closed mold, polymerization and curing in the mold, shaped into products.
Because the raw material used is liquid, with less pressure that can quickly fill the mold cavity, so reduce the clamping force and mold cost, especially suitable for the production of large-area parts.
RIM was first used only for polyurethane materials, with advances in technology, RIM can also be applied to a variety of materials (such as epoxy, nylon, polyurea and polycyclopentadiene, etc.) processing. RIM process for rubber and metal molding is the current research hot spot.
Extended information
Reaction injection molding failure causes and countermeasures:
1, the products at 120 ℃ post-curing treatment, the surface shows delamination or bubble failure. This is due to poor mixing, the supply of components ahead or behind, or both. Should improve the mixing and supply system, so that the mixing is uniform, accurate supply.
2, when the mold filling speed exceeds the predetermined limit, will produce the mold filling air fault, resulting in uneven surface quality of the product. Should be appropriate to reduce the speed of mold filling.
3, the mold surface temperature is not uniform will lead to the product appearance quality is not uniform. The mold temperature should be adjusted evenly.
4, mold cavity surface finish is too poor, so that the mold mold cavity surface error copy to the product surface. Should improve the mold surface finish.
5, mold temperature is too high will make the surface of the product to produce a thin and porous skin layer, resulting in products in the surface of the paint treatment scrap; mold temperature is too low will inhibit the reaction properties of the whole system, causing surface delamination. The mold temperature should be adjusted appropriately.
Baidu Encyclopedia-RIM