Injection molding is a method of forming shapes for industrial products. Usually rubber injection molding and precision plastic injection molding are used. Injection molding can also be divided into injection molding compression method and die casting method. Injection molding machine (abbreviated as injection machine) is the main molding equipment for making thermoplastic or thermosetting materials into various shapes of plastic products using plastic molding molds. Injection molding is achieved through injection molding machines and molds.
Through the action between the barrel of the extruder and the screw, the material is heated and plasticized, while being pushed forward by the screw, and continuously passed through the head to make various cross-section products or semi-products.
3. Rotational molding
Rotational molding is also called rotational casting. The molding method is to first add the metered plastic (liquid or powder) into the mold, and after the mold is closed, make it rotate along two vertical rotating shafts while heating the mold. Under the action of gravity and heat, the plastic raw materials in the mold are gradually uniformly coated, melted and adhered to the entire surface of the mold cavity, formed into the same shape as the mold cavity, and then cooled, shaped, and demolded to form the required shaped products.
4. Blow molding
Blow molding, also called hollow blow molding, is a rapidly developing plastic processing method. The tubular plastic parison obtained by extrusion or injection molding of the thermoplastic resin is placed in the split mold while it is hot (or heated to a softened state). After the mold is closed, compressed air is injected into the parison to inflate the plastic parison and close to the inner wall of the mold. After cooling and demolding, various hollow products are obtained.
Blister is a kind of plastic processing technology. The main principle is to heat and soften the flat plastic hard sheet, then use vacuum to absorb it on the surface of the mold, cool it and form it, and apply it to various industries.
6. Compression molding
Compression molding is an operation in which powdered, granular or fibrous plastic is put into a mold cavity at the molding temperature, and then the mold is closed and pressurized to form and solidify. Compression molding can be used for thermosetting plastics, thermoplastics and rubber materials.
It is a method that refers to the melting and plasticizing of thermoplastics through the gap of two or more parallel anti-rotating rollers, so that the melt is squeezed and stretched by the rollers to have a certain size and conform to the continuous sheet products that meet quality requirements and are finally formed by natural cooling. The calendering process is often used in the production of plastic films or sheets.
8. Foam molding
Foam molding is the process of adding appropriate foaming agents to foam materials (PVC, PE, PS) to make the plastic produce a microporous structure. Almost all thermosetting and thermoplastic plastics can be made into foam, and foam molding has become an important field in plastic processing.
The process is to wind the continuous fiber (or cloth tape, prepreg yarn) impregnated with resin glue on the core mold according to a certain rule, and then solidify and demold to obtain the product.
Laminate molding refers to a molding process that combines multiple layers of the same or different materials as a whole under heating and pressure. It is often used in plastic processing and also in rubber processing.
11. Coating and molding
Coating molding is a process of using plastisol or organosol to coat the surface of a substrate such as cloth or paper to make imitation leather products, varnished cloth or plastic wallpaper, or to coat powdered plastic on metal surfaces. Common plastic coated products include artificial leather, varnished cloth, plastic wallpaper and various metal coated products.
12. Pouring molding
Pouring molding is a method of plastic processing. In the early days of casting, liquid monomers or prepolymers were injected into the mold under normal pressure, and after polymerization, it was solidified and formed into a product with the same shape as the cavity of the mold. In the 1960s, nylon monomer casting appeared. With the development of molding technology, the traditional casting concept has changed. Polymer solutions and dispersions refer to polyvinyl chloride pastes and melt that can also be used for casting.
Dripping technology uses thermoplastic polymer materials with variable state characteristics. That is, the thermoplastic polymer material has viscous fluidity under certain conditions, and can restore the solid-state characteristics at room temperature. In the viscous state of the thermoplastic polymer material, use appropriate methods and special tools to ink-jet it into the designed form as required, and then solidify and shape it at room temperature.
14. Cold press molding
Cold press molding is a type of compression molding. Different from ordinary compression molding, it presses and molds the material at room temperature. After demolding, the molded product can be reheated or cured by chemical action.
15. Compression molding
It is mainly used in the production of thermosetting plastic products. The molding is heated to melt, then pressurized, punched, and then cross-linked and cured by heating, and the product is obtained after demolding.
16. Resin transfer molding
Resin transfer molding is a process in which resin is injected into a closed mold to infiltrate and cure the reinforcing material. This technology eliminates the need for prepregs and autoclaves, effectively reducing equipment costs and molding costs.
This technology has developed rapidly in recent years in the aircraft industry, automobile industry, and shipbuilding industry. It has been widely used and developed RFI, VARTM, SCRIMP, SPRINT and other branches to meet the application needs of different fields.
It is a pressure processing method in which a punch is used to pressurize the blank placed in a concave mold to produce plastic flow, thereby obtaining a part corresponding to the shape of the mold hole or concave and convex mold. During extrusion, the billet produces three-dimensional compressive stress. Even blanks with low plasticity can be extruded.
Thermoforming is a special plastic processing method for processing thermoplastic plastic sheets into various products. The sheet material is clamped on the frame and heated to a softened state, and under the action of external force, it is made to closely adhere to the molding surface of the mold to obtain a shape similar to the molding surface. After cooling and shaping, the product is finished.
19. 3D printing
3D printing is a kind of rapid prototyping technology. It is a technology that builds objects based on digital model files, using bondable materials such as powdered metal or plastic, and printing layer by layer. 3D printing and manufacturing are usually achieved by using digital technology material printers. It is often used to make models in mold manufacturing, industrial design and other fields, and then gradually used in the direct manufacturing of some products. There are already parts printed using this technology.
There are many different technologies for 3D printing. The difference between them lies in the way the materials are available and the construction of different layers to create parts. Commonly used materials for 3D printing include nylon glass fiber, polylactic acid, ABS resin, durable nylon materials, gypsum materials, aluminum materials, titanium alloys, stainless steel, silver plating, gold plating, and rubber materials.