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Injection Moulding Injection Molding Process
Wishsino International Group Limited | Updated: Jun 23, 2017

Injection Moulding Injection molding process

 Injection molding process

temperature control

⒈ barrel temperature: injection molding process need to control the temperature of the barrel temperature, nozzle temperature and mold temperature. The first two kinds of temperature mainly affect the plasticization and flow of plastic, and then a temperature is mainly affecting the flow of plastic and cooling. Each plastic has a different flow temperature, the same kind of plastic, due to different sources or grades, the flow temperature and decomposition temperature is different, it is due to the average molecular weight and molecular weight distribution caused by different plastic in different types of injection Machine plastic process is also different, so choose the cylinder temperature is not the same.

⒉ nozzle temperature: nozzle temperature is usually slightly lower than the maximum temperature of the barrel, which is to prevent the melt in the straight-through nozzle may occur "salivation phenomenon." The nozzle temperature can not be too low, otherwise it will cause the melt early coagulation and nozzle clogging, or because the early injection into the cavity and affect the performance of products.

⒊ mold temperature: mold temperature on the product's inherent performance and apparent quality of a great impact. The temperature of the mold depends on the presence or absence of the crystallinity of the plastic, the size and structure of the product, the performance requirements, and other process conditions (melt temperature, injection speed and injection pressure, molding cycle, etc.).

Pressure control

During the injection process, the pressure includes plasticization pressure and injection pressure, and directly affects the plasticization and quality of the plastic.

⒈ plasticization pressure: (back pressure) with screw-type injection machine, the top of the screw in the screw rotation back when the pressure is called plasticization pressure, also known as back pressure. The size of this pressure can be adjusted by the relief valve in the hydraulic system. In the injection, the size of plasticizing pressure is with the screw design, product quality requirements and the type of plastic and need to change, if these conditions and the screw speed are unchanged, then increase the plasticization pressure will strengthen the shear Effect, which will increase the melt temperature, but will reduce the efficiency of plasticization, increase the counter current and leakage, increase the driving power.

In addition, increasing the plasticizing pressure often results in a uniform temperature of the melt, uniform mixing of the colorants, and removal of the gas from the melt. general

The pressure curve in injection molding

The pressure curve in injection molding

In operation, the decision to plasticize the pressure should be to ensure that the quality of products under the premise of the lower the better, the specific value is different with the use of plastic varieties, but usually rarely more than 20 kg / square centimeter.

⒉ injection pressure: in the current production, almost all of the injection machine injection pressure is the top of the plunger or screw on the plastic

The pressure applied (by the oil pressure conversion) shall prevail. The effect of injection pressure on injection molding is to overcome the flow resistance of the plastic from the cartridge to the cavity, the rate at which the melt is charged, and the melt to be compacted.