Plastic injection molding is a method of forming a thermoplastic or thermosetting molding material in a mold cavity by uniformly plasticizing it in a heating cylinder and then by a plunger or a moving screw to a closed mold. Injection molding Plastic Injection Molding is suitable for almost all thermoplastics. In recent years, injection molding has also been successfully used to shape certain thermosetting plastics. Injection molding of the molding cycle is short (a few seconds to a few minutes), the quality of molded products from a few grams to dozens of kilograms, can shape a complex shape, accurate size, with metal or non-metallic insert molding. Therefore, the method of adaptability, high production efficiency. Injection molding machine is divided into plunger injection molding machine and screw injection machine two categories, by the injection system, the mold clamping system and the three major parts of the mold;
Plastic injection molding
Exhaust type injection molding application of the exhaust injection machine, in the middle of the barrel with exhaust port, Plastic Injection Molding also connected with the vacuum system, when the plastic plastic, the vacuum pump can be combined with water vapor, monomer, volatile Substances and air by the exhaust port away; raw materials do not have to pre-drying, thereby enhancing production efficiency and improve product quality. Particularly suitable for polycarbonate, nylon, plexiglass, cellulose and other materials easy to absorb moisture.
Flow injection molding can be used for ordinary mobile screw injection machine. That is, the plastic is continuously plasticized and squeezed into a mold cavity with a certain temperature. After the plastic is filled with the cavity, the screw stops rotating. The thrust of the mold keeps the mold material under pressure for an appropriate time. Flow injection Plastic Injection Molding molding overcomes the limitations of equipment for the production of large products, which can exceed the maximum injection volume of the injection machine. It is characterized by the plasticized objects are not stored in the barrel, but continue to squeeze into the mold, so it is a combination of extrusion and injection method.
A total injection molding is done by injecting a machine with two or more injection units, injecting different kinds or different colors of plastic, simultaneously or sequentially into the mold. In this way can produce a variety of colors and (or) a variety of plastic composite products, a representative of the total injection molding is two-color injection and multi-color injection.
No flow channel
The mold is not provided in the mold, and by the extension of the injection nozzle directly melt the melt into the mold cavity in the molding method. During the injection process, the plastic in the flow path is kept in a molten flow state and does not come off with the product during stripping, so that the part has no runner residue. This molding method not only saves raw materials, reduces costs, and reduces processes that can achieve fully automated production.
The principle of reactive injection molding is to measure the reaction raw material by metering device and then pumped into the mixing head, mixed in the mixing head, and then high-speed injection into the closed mold, fast curing, stripping, removal of products. It is suitable for processing polyurethane, epoxy resin, unsaturated polyester resin, silicone resin, Plastic Injection Molding alkyd resin and some thermosetting plastics and elastomers.
Granular or pelletized thermosetting plastics, in the strict control of the temperature of the barrel, through the role of the screw, plastic into a viscous state, at a higher injection pressure, the material into a certain temperature range of cross-cutting curing mold. Thermosetting plastic injection molding in addition to changes in physical state, there are chemical changes. Therefore, compared with the injection molding of thermoplastic, in the molding equipment and processing technology there is a big difference.