Compression molding process

The compression molding process can be divided into the following types according to the physical state of reinforcement materials and the types of molded materials:

(1) Fibrous material molding method: Put the pre-mixed or pre-impregnated fibrous molding material into a metal mold, and form a composite product under a certain temperature and pressure.
(2) Shredded cloth molding method: cut the leftover material of glass fiber cloth or other fabrics such as linen cloth, organic fiber cloth, asbestos cloth or cotton cloth impregnated with resin glue into pieces, and then heat and press in the mold to form Composite products. This method is suitable for forming products with simple shapes and general performance requirements.
(3) Fabric molding method: The two-dimensional or three-dimensional fabric woven into the desired shape is impregnated with resin glue, and then placed in a metal mold to heat and press to form a composite product.
(4) Laminate molding method: Cut glass fiber cloth or other fabrics pre-impregnated with resin glue into the required shape, and then heat or press in a metal mold to form a composite product.
(5) Winding and molding method: the continuous fiber or cloth (belt) pre-impregnated with resin glue is wound on the core mold through a special winding machine to provide a certain tension and temperature, and then put into the mold for heating and pressing Molded composite products.
(6) Sheet plastic (SMC) molding method: Cut the SMC sheet according to the product size, shape, thickness, etc., and then superimpose the multilayer sheet and put it into a metal mold to heat and press the product.
(7) Pre-formed blank molding method: First, the preformed blanks with similar shapes and sizes of chopped fibers are put into a metal mold, and then the prepared binder (resin mixture) is injected into the mold. It is molded under certain temperature and pressure.
(8) Orientation auxiliary molding: Lay the unidirectional prepreg products in the main stress direction, and then compression molding. The fiber content of the products can reach 70%, which is suitable for forming products with high unidirectional strength requirements.
(9) Molding powder molding method: Molding powder is mainly composed of resin, filler, curing agent, coloring agent and release agent. The resins are mainly thermosetting resins (such as phenolic resins, epoxy resins, amino resins, etc.). Thermoplastic resins with high molecular weight, poor fluidity, and high melting temperature that are difficult to be injected and extruded can also be made into molding powder. The molding process of molding powder and other molding materials are basically the same. The main difference between the two is that the former does not contain reinforcing materials, so its products have lower strength and are mainly used for secondary stress parts.
(10) Adsorption preform molding method: Adsorption method (air adsorption or wet slurry adsorption) is used to preform glass fiber into a preform with a structure similar to the molded product, and then place it in the mold and place it on top of it. Pour the resin paste and shape it under certain temperature and pressure. The cost of materials used in this method is low, longer chopped fibers can be used, and it is suitable for forming products with more complex shapes. It can be automated, but the equipment cost is higher.
(11) Bulk molding compound molding method: Bulk molding compound (BMC) is a fiber-reinforced thermosetting plastic, and it is usually composed of unsaturated polyester resin, chopped fibers, fillers and various additives. A mass-shaped prepreg that is thoroughly mixed. Low shrinkage additives are added to BMC, which greatly improves the appearance performance of the product BMC.
(12) Felt molding method: This method uses resin (mostly phenolic resin) to impregnate glass fiber mat, and then dry it into a prepreg mat, cut it into the required shape, and place it in a mold. Products. This method is suitable for forming large-scale thin-walled products with simpler shapes and little change in single thickness.