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Nozzle temperature and pressure control for plastic bottle injection processing

Update:24-07-2020
Summary:

The temperature that needs to be controlled in the proc […]

The temperature that needs to be controlled in the process of plastic bottle injection processing includes barrel temperature, nozzle temperature and mold temperature. During operation, the first two temperatures mainly affect the plasticization and activity of the plastic, and the second temperature mainly affects the activity and activity of the plastic. cool down. Every kind of plastic has different activity temperature. The same kind of plastic has different activity temperature and differentiation temperature because of different origin or brand. This is because the average molecular weight and molecular weight distribution are different. Therefore, in the production of sports plastics Bottles, plastic water cups, cosmetic plastic, feed bottles, daily-use bottles, caps, food packaging plastic bottles, cosmetic plastic bottles, health care products plastic bottles, medicinal plastic bottles, beverage bottles, life plastic bottles, juice machine bottles, children's toys, various pigments Plastic bottles, various types of heterogeneous plastic products, industrial plastic products, and other types of products have different plasticization processes in different types of injection machines, so the temperature of the selected barrels is also different.

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Nozzle temperature of plastic bottle injection processing

The nozzle temperature of the injection molding process is usually slightly lower than the barrel temperature, which is to prevent the "salivation" that may occur in the straight-through nozzle of the melt. The temperature of the nozzle should not be too low, otherwise the nozzle will be blocked due to the formation of early solidification of the melt, or the function of the product will be affected due to the injection of the early solidification material into the cavity.

Mold temperature for injection molding

Mold temperature has a great influence on the inner function and apparent quality of the product. The unevenness of the mold temperature depends on the crystallinity of the plastic, the size and structure of the product, the functional requirements, and other process conditions (melt temperature, injection speed and injection pressure, molding cycle, etc.).

Pressure control for injection molding

The pressure in the injection molding process includes plasticizing pressure and injection pressure, and directly affects the plasticization of plastics and product quality.

When the plastic bottle injection molding process uses a screw injection machine during operation, the pressure on the top of the screw when the screw is rolled and retracted is called the plasticizing pressure, also known as the back pressure. The size of this pressure can be adjusted through the relief valve in the hydraulic system. In the injection, the size of the plasticizing pressure is changed with the planning of the screw, the requirements of the product quality, and the variety of plastics. If these conditions and the speed of the screw are the same, adding the plasticizing pressure will strengthen the shear The effect is to increase the temperature of the melt, but reduce the efficiency of plasticization, increase the countercurrent and leakage current, and increase the driving power.

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