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Control of processing temperature of injection molded parts

Feb 24, 2022

There are many types of plastics, and many plastic materials have different melting times. Since plastics have no specific melting point, the so-called melting point is a temperature range in a molten state. The structure and composition of plastic molecular chains are different, so the impact on its fluidity is also different. , then the temperature control of injection molding parts manufacturers is also very important in the processing of injection molding parts. Today, the editor of JHS Plastics will talk to you about the injection molding process and the temperature control of each process.

1. Mold temperature

Some plastic materials require higher mold temperature due to high crystallization temperature and slow crystallization rate, and some require higher or lower temperature due to control of size and deformation, or the need for demolding, such as PC general requirements In order to achieve better appearance and improve fluidity, the mold temperature sometimes needs to be more than 160 degrees. Therefore, the mold temperature has an invaluable effect on improving the appearance, deformation, size and plastic mold of the product.

2. Injection pressure

The melt overcomes the resistance required to advance, which directly affects the size, weight and deformation of the product. Different plastic products require different injection pressures. For materials such as PA and PP, increasing the pressure will make their fluidity significantly To improve, the injection pressure determines the density of the product, that is, the appearance gloss. It does not have a fixed value, and the more difficult it is to fill the mold, the higher the pressure of the injection molded part.

3. The temperature of the barrel

The temperature of the melt is very important, and the temperature of the injection barrel used is only a guide. The melt temperature can be measured at the nozzle or using 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 processing a particular grade of plastic, start with the lowest setting.

For ease of control, the shot tank is divided into zones, but not all are set to the same temperature. For long runs or high temperatures, set the first zone temperature to a lower value, this will prevent premature melting and shunting of the plastic. Make sure the hydraulic fluid, hopper closure, mold and shot cylinder are at the correct temperature before starting injection molding.

4. Melt temperature

The melt temperature plays a major role in the flow properties of the melt. Since the plastic does not have a specific melting point, the so-called melting point is a temperature range in a molten state. The structure and composition of the plastic molecular chain are different, so its fluidity is The influence of temperature is also different. Rigid molecular chains are obviously affected by temperature, such as PC, PPS, etc., while the fluidity of flexible molecular chains such as PA, PP, PE, etc. is not obvious by changing temperature, so it should be adjusted according to different materials. Reasonable injection temperature.

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