PP injection molding parts

The main process parameters of injection molded parts include:

1. Barrel temperature: the melt temperature is very important, and the temperature of the injection cylinder used is only guiding. The melt temperature can be measured at the nozzle or by the air jet method. The temperature setting of the injection cylinder depends on the melt temperature, screw speed, back pressure, injection volume, and injection molding cycle. If you have no experience in processing a particular grade of plastic, please start with the lowest setting. For ease of control, the injection cylinder is divided into zones, but not all are set to the same temperature. If operating for a long time or at a high temperature, set the temperature of the first zone to a lower value, which will prevent premature melting and diversion of plastics. Before injection molding, ensure that the hydraulic oil, hopper closure, mold, and injection cylinder are at the correct temperature.

2. Melt temperature: melt temperature plays a major role in the fluidity of the melt. Since plastic has no specific melting point, the so-called melting point is a temperature section in the molten state. The structure and composition of the plastic molecular chain are different, so it has different effects on their fluidity. Rigid molecular chain is affected by temperature, such as PC, PPS, etc., while flexible molecular chain, such as PA, PP The fluidity of PE is not obvious by changing the temperature, so the reasonable temperature of injection molded parts should be adjusted according to different materials.

3. Mold temperature: some plastic materials need higher mold temperature due to high crystallization temperature and slow crystallization speed. Some plastic materials need higher or lower temperatures due to the need of controlling size and deformation or demoulding. For example, PC generally requires more than 60 degrees, while PPS sometimes needs more than 160 degrees to achieve a better appearance and improve fluidity, Therefore, the mold temperature plays an inestimable role in improving the appearance, deformation, size, and rubber mold of the product.

4. Injection pressure: the melt overcomes the resistance required to move forward, which directly affects the size, weight, and deformation of the product. Different plastic products require different injection pressure. For materials such as PE and PP, increasing the pressure will significantly improve their fluidity. The injection pressure determines the density of the product, that is, the appearance luster. It has no fixed value, and the more difficult it is to fill the mold, the pressure of the injection molded part also increases.

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