Molding process of FRP grating

The compression molding process is the oldest and most dynamic molding method in the production of composite materials. It is a method of adding a certain amount of premix or prepreg into a metal mold, and then heating and pressing it to solidify and form it.

The main advantages of the compression molding process are:

① High production efficiency, easy to achieve specialization and automation in production;

② The product has high dimensional accuracy and good repeatability;

③ Smooth surface, no need for secondary modification;

④ Capable of producing products with complex structures in one go;

⑤ Due to mass production, the price is relatively low.

The shortcomings of compression molding are that the mold manufacturing is complex, the investment is large, and coupled with the limitations of the press machine, it is most suitable for mass production of small and medium-sized composite material products. With the continuous improvement and development of metal processing technology, press manufacturing level, and synthetic resin process performance, the tonnage and table size of presses continue to increase, and the molding temperature and pressure of molding materials are relatively reduced, which gradually leads to the development of large-scale molded products. Currently, it is possible to produce large automotive parts, bathtubs, integrated bathroom components, etc.

The molding process can be divided into the following types based on the physical state of the reinforcing material and the variety of molding materials:

① Fiber material molding method is a method of molding composite material products by injecting pre mixed or pre impregnated fiber shaped molding materials into metal molds at a certain temperature and pressure. This method is simple and easy to implement, with a wide range of applications. According to different specific operations, there are premix molding and prepreg molding methods.

② The crushed fabric molding method involves cutting the scraps of glass fiber cloth or other fabrics, such as linen, organic fiber cloth, asbestos cloth, or cotton cloth, that have been soaked in resin glue into small pieces, and then heating and pressing them in a metal mold to form composite material products.

③ The fabric molding method involves impregnating two or three-dimensional fabrics pre woven into the desired shape with resin glue, and then heating and pressing them into a metal mold to form composite material products.

④ The laminated molding method cuts glass fiber cloth or other fabrics pre impregnated with resin adhesive into the desired shape, and then forms composite material products by heating or pressing them in a metal mold.

⑤ The winding molding method involves using a specialized winding machine to provide a certain tension and temperature to wrap continuous fibers or cloth (tape) pre impregnated with resin adhesive solution onto a core mold, and then placing it into the mold for heating and pressure to form composite material products.

⑥ The sheet plastic (SMC) molding method cuts SMC sheets according to the requirements of product size, shape, thickness, etc., and then stacks multiple layers of sheets and puts them into a metal mold for heating and pressing to form the product The preform molding method first places a preform with similar shape and size of short cut fiber products into a metal mold, and then injects a prepared adhesive (resin mixture) into the mold to form at a certain temperature and pressure.

There are many types of molding materials, which can be pre impregnated materials, pre mixed materials, or raw materials. The main types of molding materials currently used include: pre impregnated tape, fiber premix, BMC, DMC, HMC, SMC, XMC, TMC, and ZMC.