Foam plastic casting process and equipment
DATE：2021/9/27 8:46:48 / READ： / SOURCE：This station
Foam plastic casting process and equipment
The molding of foam is similar to but not exactly the same as that of metal. Plastic casting molding is mainly used for foam molding of thermoset plastics. In the casting process, the polycondensation reaction process of high-quality materials and the molding and shaping process of foaming go hand in hand. Therefore, each component of the raw material must be fully processed before flow molding at home. In the mixing process, only a small pressure is applied to the fluid and the mold or in a free state during pouring. The strength requirements for the molding and shaping settings of the mold are lower, and the investment is less; the product size is less restricted, and the internal stress of the product is small. It is more convenient to produce large-scale products, and you can also go to the site for construction. The disadvantage is the poor dimensional accuracy of the finished product.
Foam plastic casting molding is mainly used in polyurethane foam, urea-formaldehyde foam, other such as phenol foam, polyvinyl methylal foam, epoxy foam, silicone foam, water-containing polyester low-foam plastic, etc. Pouring method can be used for foam molding. However, the first three types of industrialized production are mainly formed, especially polyurethane foam has a wide range of applications and rapid development. This chapter will take it as the leading introduction.
Urethane foam is different according to the raw materials used. It can be divided into polyester polyurethane foam and polyurethane foam. According to the soft and hard properties of the texture, it can be divided into rigid polyurethane foam, semi-rigid polyurethane foam and soft polyurethane foam. According to the production procedure, it can be divided into two categories: one-step method and two-step method. According to the shape of the product, it can be divided into three categories: block finished molded products and coatings. Since foam casting molding generally undergoes intense mixing, this mechanical foam molding also falls into this category.
The compound ester foam type has good performance, small bulk density, high strength, low thermal conductivity, shockproof ability to absorb impact load, sound insulation, etc., and it has a wide range of uses. High-quality polyurethane foam has the highest output, and is mainly used as furniture, seat cushions, mattress clothing, packaging materials, materials, dust absorption, sound absorption, shockproof materials, daily necessities and carpet pads. Rigid and semi-rigid polyurethane foams are mostly used in industry and military, such as sandwich materials for radar radomes, sound-absorbing materials, thermal insulation materials for chemical equipment and instruments, thermal insulation materials for refrigeration and oil transportation systems, and various Packaging materials for electrical meters. Since the oil crisis in 1973, foreign countries have attached great importance to energy conservation. Because rigid polyurethane has the best thermal insulation performance, governments of various countries have formulated regulations to encourage enterprises to use rigid polyurethane foam. The casted urea-formaldehyde foam is a white block with a closed-cell structure. Its biggest advantages are light weight, low thermal conductivity, and relatively low price. It can be used in industry, agriculture, national defense, and transportation. However, the urea-formaldehyde foam has better water absorption. Strong, low mechanical properties, not suitable for structural materials. The application of polyvinyl formal foam plastic is also expanding day by day. It is not only widely used as a household mop material but also can be used for a variety of products that require high water absorption, especially in medical products, due to its high hygiene and safety conditions. Therefore, it has been reused as a replacement material for human organs.
Author：admin