Brief introduction of the current situation of dom

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Brief introduction of domestic rotational molding technology

rotational molding technology is also known as rotational or rotary molding technology. It is to put plastic powder into the mold, so that the powder rotates around two mutually perpendicular axes in the mold while heating. In the process of rotation, the powder keeps turning, rubbing against each other and dragging the powder on the surface of the mold, so that the normal material used by the powder to protect the equipment continues to move above the mold wall until its motion force is enough to overcome the gravity of the powder, the powder can cross the powder pool to reach the opposite mold wall, and the powder rotates 360 degrees with the mold

after repeated heating and rotation, the powder will melt and evenly adhere to the inner wall of the mold, and melt into one. After reaching the required thickness, it will be cooled and shaped, and the hollow products can be taken out of the mold

compared with the traditional molding methods of hollow plastic products, rotational molding has incomparable advantages in equipment investment cost, manufacturing cycle and process flexibility. It has become the most ideal, economical and effective method for small batch production of medium-sized, large or super large fully enclosed or semi enclosed hollow seamless containers

the characteristics of rotational molding process are outstanding. The investment of rotational molding process equipment is less, the mold processing cost is low, and the comprehensive cost of producing products of the same volume is low. Save raw materials, almost 100% of the materials can be converted into products. There is no runner, gate, etc. in the mold, no waste will be generated, and the wall thickness of the product is uniform. The chamfer is slightly thickened, which can give full play to the material efficiency

the rotational molding process is suitable for producing large and super large products that remain for a period of time, and is suitable for forming hollow parts with various complex shapes. In the process of rotary molding, materials are gradually coated on the surface of the mold, which has a strong ability to replicate the fine structures such as patterns on the surface of the mold cavity. At the same time, because the mold is not under pressure in the whole molding process, various fine and complex molds can be directly made by means of precision casting, including various accessories of the experimental machine, to form various resin based composite products such as toys and animal models

the rotational molding process is also suitable for the production of resin matrix composite products with multi-layer materials. To roll molding multi-layer products, only reasonably matched resins with different melting points need to be loaded into the mold. During the molding process, the materials with low melting temperature are heated and melted first, and adhered to the mold cavity wall to form the outer layer of the workpiece. After that, the materials with higher melting temperature will be melted again and attached to the outer materials to form an inner layer, or the outer resin will be loaded into the mold first, and then the outer layer of the parts will be formed into the outer layer of the parts, and then the inner resin will be added to make the multi-layer parts

the products made by rotational molding have no internal stress, almost no orientation or residual strain, and there are no problems such as hollows, transparency, deformation and cracking with lower crystallinity

rotational molding is suitable for the production of multi variety and small batch resin matrix composite products, and it is very easy to change the color of composite materials. In addition, the process has the advantages of simple molding, strong adaptability and convenient mold replacement. The equipment and chess set have simple structure, convenient and rapid processing and manufacturing, and low price, so it is very beneficial to change products. A rotary forming machine can also form products of very different sizes and shapes at the same time in the production process

rotational molding also has some disadvantages, such as high energy consumption, long molding cycle, poor dimensional accuracy of molded products, high labor intensity, etc

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