Adverse factors of plastic material and injection mold are in the following:

  1. The plastic melt is provided with high flow viscosity, resulting in poor flow and filling capacity.
  2. The plastic melt has poor plasticity, excessively low temperature for plastication and unbalanced melt temperature, which altogether result in the poor melt fluidity.
  3. Mold temperature is overlow or unbalanced, temperature of some parts is too low and temperature of melt injected into the cavity drops too fast.
  4. The flow of melt in the mold is too long or too complicated, the resistance against filling is large and the filling is not smooth, even resulting instagnation.
  5. Temperature of nozzle is too low and the cold-slug well of feed system is improperly set, resulting in jam and stagnation when the front cold material of melt enters the cavity.
  6. During the filling, molds are not sufficiently aired and the gas has not been discharged in time, thereby resulting in the expansion of filling resistance.


  1. Use plastics with low viscosity and sound fluidity or adjust prescription of plastics and reduce viscosity of melt.
  2. Improve barrel temperature, increase injection pressure, raise melt temperature to reduce viscosity, and improve plastication quality
  3. Improve mold temperature, and uniformity thereof, raise nozzle temperature and properly set cold-slug well.
  4. Increase dimension of the runner and gate and properly set gate position to avoid overlong flow during filling and overlarge loss of pressure when the melt enters cavity.
  5. Properly design mold exhausting scheme and change number of position of gate as well as position of parting line when necessary to achieve sound exhausting effect.


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