Plastic mold has a vital influence on the processing of plastic products. And mold design level and manufacturing capacity also reflects a country’s industrial level, in recent years the development of the production of plastic molding mold and level very fast speed, high efficiency, automation, large-scale, precision, long life of the mold under the proportion is more and more big from the mold design, processing methods, processing equipment, surface treatment and so on several aspects to summarize the development situation of mould.
Plastic molding method and mold design
Gas assisted molding, gas assisted molding is not a new technology, but in recent years, it has developed rapidly and some new methods have emerged. Liquefied gas assisted injection is to inject a kind of preheated special vaporize liquid into the plastic melt from the injection. The liquid is heated and vaporized in the mold cavity to expand, making it hollow, and pushing the melt to the surface of the mold cavity. This method can be used for any thermoplastic plastic. Vibration gas assisted injection is to apply vibration energy to the plastic melt through the compressed gas of the oscillating product, so as to control the micro-structure of the product and improve the performance of the product. Some manufacturers convert the gas used in gas assisted molding into thinner products, and can also produce large hollow products with higher quality and lower cost, but the key point is the leakage of water.
Push and pull molding mold, two or more channels are set around the mold cavity and connected with two or more injection devices or reciprocating pistons. After the injection is completed, the screw or piston of the injection device moves back and forth to push and pull the melt in the mold cavity before the melt solidifies. This technology is called dynamic pressure maintaining technology, which aims to avoid the problem of large shrinkage when thick products are molded by traditional molding methods, High pressure forming thin shell products. Thin shell products are generally products with a long flow ratio. Most of them use multi-point gate molds. However, multi-point pouring will cause welding seams, which will affect the visual effect of some transparent products. Single point pouring is not easy to fill the mold cavity, so they can be formed by high pressure forming technology. For example, the U.S. Air Force, F16 fighter cockpit is produced by this technology, which has been used to produce PC automobile windscreens, The injection pressure of high-pressure molding is generally more than 200MPA, so the mold material should also choose high strength and rigidity with high Young’s modulus. The key of high-pressure molding is the control of mold temperature. In addition, pay attention to the smooth exhaust of mold cavity. Otherwise, the plastic will be burnt due to poor exhaust caused by high-speed injection.
Post time: Nov-29-2022
