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Do you know how to control the temperature of the injection molding process?

2017.09.14

Source: Golden Eagle Press

Reading:

The melt temperature is very important, and the temperature of the cylinder used is only guidance.The melt temperature can be measured at the nozzle or by air injection.The temperature setting of the ejection cylinderdepends on the melt temperature, screw speed, back pressure, injection quantity and injection molding cycle. If you have no experience working with a particular level of plastic, start with the lowest setting. For easy control, the ejector cylinder is divided into sections, but not all of them are set to the same temperature. If the operation time is long or operating at high temperature, please set the temperature of the first area to a lower value, which will prevent the premature melting and shunt of plastics. Ensure that the hydraulic oil, hopper closure, mould and ejector cylinder are at the correct temperature before the injection molding begins.

1. Cylinder temperature:

The melt temperature is very important, and the temperature of the cylinder used is only guidance. The melt temperature can be measured at the nozzle or by air injection. The temperature setting of the ejection cylinder depends on the melt temperature, screw speed, back pressure, injection quantity and injection molding cycle. If you have no experience working with a particular level of plastic, start with the lowest setting.


For easy control, the ejector cylinder is divided into sections, but not all of them are set to the same temperature. If the operation time is long or operating at high temperature, please set the temperature of the first area to a lower value, which will prevent the premature melting and shunt of plastics. Ensure that the hydraulic oil, hopper closure, mould and ejector cylinder are at the correct temperature before the injection molding begins.

2. Melting temperature:

Melt temperature of the melt flow behavior plays a main role, because no specific plastics, melting point, the melting point is a segment of the temperature of the molten state, the plastic different molecular chain structure and composition, and therefore have different influence on its liquidity, molecular chain rigidity affected by temperature is obvious, such as PC, PPS, and flexible chain, such as: PA, PP, PE and so on by changing the liquid temperature is not obvious, so should be based on different materials to reasonable injection temperature calibration. Vertical injection molding machine, precision injection molding machine.


3. Mold temperature:

Some plastic materials due to their high crystallization temperature, crystallization speed is slow, need higher mold temperatures, some due to control the size and deformation, or the need of mold release, to high temperature or low temperature, such as PC generally requires more than 60 degrees, the PPS in order to achieve better appearance and improve liquidity, die temperature sometimes need more than 160 degrees, and mold temperature for improving product appearance, shape, size, has not to appraise the effect of plastic mold.

4. Injection pressure:

Melt forward to overcome the resistance, a direct impact on product size, weight and deformation, etc., different injection pressure needed for plastic products, such as PA, PP material, such as increasing pressure will significantly improve its liquidity, injection pressure determines the density of the product, namely the gloss appearance. It has no fixed numerical value, and the more difficult the mold filling is, the pressure of injection molding is also increased.