BMC (DMC) material is the abbreviation of bulk (dough) molding compounds, that is, bulk molding compounds. It is often called unsaturated polyester group molding compound in China. Its main raw materials are mass prepregs made of GF (chopped glass fiber), up (unsaturated resin), MD (filler calcium carbonate) and various additives. BMC materials were first applied in the former West Germany and Britain in the 1960s, and then developed greatly in the United States and Japan in the 1970s and 1980s respectively. Because BMC bulk molding compounds have excellent electrical properties, mechanical properties, heat resistance, chemical corrosion resistance, and adapt to various molding processes, they can meet the performance requirements of various products, so they are more and more popular with users.
(1) Characteristics and application of BMC
BMC has good physical, electrical and mechanical properties, so it is widely used, such as making mechanical parts such as gearbox components, intake pipes, valve covers, bumpers and so on; It is also widely used in aviation, architecture, furniture, sanitary products and other aspects requiring earthquake resistance, flame retardancy, beauty and durability; In its traditional electrical field, its use is more and more extensive.
(2) Typical products
Electrical parts (insulator, switch 29, meter box, circuit breaker shell, terminal block, various domestic or commercial electromechanical product shells), automobile parts (headlight reflector, rear door, speaker shell, etc.), meter shell, sound equipment shell.
(3) BMC forming method
BMC injection molding machine is mainly a process for BMC bulk material, which is forced into the BMC barrel through the BMC feeder, then transmitted to the front of the barrel through the screw, and then injected into the mold cavity for curing and molding.
BMC is a thermosetting material. The temperature of the barrel of the injection molding machine should not be too high. It is generally set at 60 degrees to facilitate the flow of materials.
BMC injection molding machine is mainly a professional equipment for producing thermosetting lumpy materials. There is a set of hydraulic system in the feeding part, which forces the lumpy materials into the barrel when the screw is expected. BMC injection molding machine is suitable for molds with complex structure, which are processed by injection molding, with high product efficiency and low labor intensity
BMC molding methods include compression molding, transfer molding and injection molding. Recently, injection molding is the main method.
① Compression molding method, see SMC molding method.
② Transfer molding method. The equipment has pot type and auxiliary piston type, mainly auxiliary piston type.
Post time: Jul-12-2022