Composite Material Solid Top Manhole Cover

The composite manhole cover can be divided into two types: BMC and SMC according to market demand, production process and materials: BMC (DMC) material is the abbreviation of Bulk (Dough) molding compounds. Often referred to as unsaturated polyester bulk molding compound. Its main raw material is a mass-shaped prepreg that is fully mixed with GF (chopped glass fiber), UP (unsaturated resin), MD (filler) and various additives. BMC materials were first used in the former West Germany and the United Kingdom in the 1960s, and then developed in the United States and Japan in the 1970s and 1980s, respectively. Because BMC bulk molding compound has excellent electrical properties, mechanical properties, heat resistance, chemical resistance, and adapts to various molding processes, it can meet the performance requirements of various products. It is widely used in automobile production and railway transportation. , Construction accessories, mechanical and electrical products and other fields.   SMC composite material is the abbreviation of Sheet molding compound. The main raw materials are composed of GF (special yarn), UP (unsaturated resin), low shrinkage additives, MD (filler) and various additives. It first appeared in Europe in the early 1960s. Around 1965, the United States and Japan developed this technology one after another. In the late 1980s, China introduced advanced foreign SMC production lines and production techniques. SMC composite materials and SMC molded products have excellent electrical insulation properties, mechanical properties, thermal stability, and chemical resistance. Therefore, the application range of SMC products is quite common.   The current development trend is SMC composite materials to replace BMC materials.