How to control the injection molding machine temperature?

The temperature that the injection molding machine needs to control during the injection molding process includes the barrel temperature, nozzle temperature and mold temperature. The first two temperatures have an important impact on the plasticization and fluidity of the plastic, while the latter temperature has an important impact on the fluidity and cooling of the plastic.

How to control the injection molding machine temperature?
1. Injection molding machine barrel temperature
The selection of the barrel temperature of the injection molding machine is related to the characteristics of the plastic, especially the fluidity temperature (Tf) or melting point (TM) of the plastic. For amorphous plastics, the high temperature at the end of the barrel should be higher than Tf, while crystalline plastics should be higher than Tm, but the temperature decay of the plastic should be lower than the polymer's dissolution temperature (Td).

Therefore, the good temperature range of the barrel should be between Tf or Tm-Td. For plastics with a narrow Tf or Tm-Td interval, such as polyvinyl chloride and polyoxymethylene, the barrel temperature should be controlled at a slightly lower level, while for plastics with a wide Tf or Tm-Td interval, such as polyethylene and polypropylene , The barrel temperature can be slightly higher. In addition, the influence of heat resistance, the content and distribution of plastics, fillers and reinforcing agents, handicrafts and injection molds, and injection equipment should also be considered. The distribution of the barrel is stable, and the barrel gradually rises from the nozzle to the end, so that the temperature of the raw material rises uniformly, and the purpose of plasticization and symmetry is achieved.

2. Nozzle temperature of injection molding machine
Because when the solution is based on the nozzle, the material temperature will increase with the increase of the cutting speed (about 103-102), the nozzle temperature is slightly lower than the high temperature of the barrel, but if the temperature is too low, the injection working pressure will increase, or The raw materials will condense in advance, which will affect the quality of handicrafts. Since there are many factors that affect polymer fluidity, it is generally adjusted according to "air injection" or "art visual analysis method" before molding to determine the barrel temperature and nozzle temperature of the injection molding machine.

3. Mold temperature of injection molding machine
Mold temperature has a considerable influence on the quality of handicrafts. The choice depends on whether the polymer is crystallized, the specifications and structure of the handicrafts, the characteristics of the regulations, and other injection standards (solution temperature, injection rate and working pressure, molding cycle). For amorphous polymers, the mold temperature has an important influence on the viscosity (fluidity) of the solution. If the solution viscosity of the raw material is low, such as Ps, the mold temperature can be slightly lower to increase the output.

If the viscosity of the solution is higher (such as mPPE, PSF), the higher mold temperature is: 120°C~140°C for mPPE, and 140°C~130°C for PSF. For crystalline polymers, the crystals are non-isothermal in the injection molding machine mold. The mode temperature of the injection molding machine should be set at the periphery of the temperature (tcm) between Tg and Tm, or a slightly lower position.

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