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18 Common Problems Encountered in Plastic Processing(1)

18 Common Problems Encountered in Plastic Processing(1)

2022-07-22 09:50:46

We believe that you have more or less encountered many problems in the injection molding process, such as dissatisfaction, flash, surface depression, size change, and other defects. These defects may be caused by mold design, the precision of the injection molding machine, etc., or the operator does not master the appropriate process conditions. The factors are complex, varied, and affect each other.

 

plastic processing

 

Bubble

 

◆ possible causes related to process and equipment

 

  1. The barrel temperature is too high
  2. The injection pressure and back pressure are too low.
  3. Insufficient holding pressure (time)
  4. The rate of fire is too high
  5. Insufficient mold filling
  6. The temperature setting of each area of the material pipe is poor

 

◆ possible causes related to the mold

 

  1. The mold temperature at the wall thickness (stiffener) is too high
  2. The gate or runner is poor
  3. Poor choice of gate type or position
  4. The gate solidifies too early
  5. The reinforcement is too thick
  6. Mold temperature is too low
  7. Poor exhaust

 

◆ possible causes related to materials

 

  1. The fluidity and shrinkage of materials are unqualified
  2. Excessive amount of returned materials
  3. Raw materials are not fully dried

 

Fusion joint

 

◆ possible causes related to process and equipment

 

  1. The injection pressure (speed) is too low or too high
  2. The back pressure setting is inappropriate
  3. The material pipe temperature is too low

 

◆ possible causes related to the mold

 

  1. Mold temperature is too low
  2. The gate or runner is too small
  3. Poor exhaust
  4. The sprue is too long

 

◆ possible causes related to materials

 

  1. Poor liquidity
  2. Too much lubricant
  3. There are foreign substances in the material

 

Jetting

 

◆ possible causes related to process and equipment

 

  1. The firing speed is too fast
  2. The melt temperature is too high or too low
  3. The diameter of the nozzle is too small
  4. The material pipe temperature is too high or too low

 

◆ possible causes related to the mold

 

  1. Improper gate type or position
  2. Improper gate shape
  3. Mold temperature is too low
  4. The gate solidifies too early

 

◆ possible causes related to materials

 

  1. Improper material fluidity

 

Size difference

 

◆ possible causes related to process and equipment

 

  1. Unstable feeding.
  2. The screw speed is unstable.
  3. The temperature is out of control and the back pressure is unstable.
  4. The screw reset is unstable, with changes of more than 0.4mm
  5. The forming cycle is unstable.

 

◆ possible causes related to the mold

 

  1. The strength and rigidity of the mold are insufficient.
  2. Bad the first mock examination multi-cavity form is used.
  3. The setting of the ejection system, pouring system, and cooling system is unreasonable.

 

◆ possible causes related to materials

 

  1. The material is poorly dried and the particles are uneven.
  2. The shrinkage of raw materials is too large.
  3. There are batch differences in material viscosity

 

Albinism

 

◆ possible causes related to process and equipment

 

  1. Filling is too urgent
  2. Improper melt temperature
  3. The injection pressure is too high
  4. The diameter of the nozzle is too small
  5. Nozzle temperature is too low

 

◆ possible causes related to the mold

 

  1. Improper gate type or position
  2. Gate diameter is too small
  3. Mold temperature is too low
  4. Insufficient cold charging well
  5. Uneven thickness at sharp bends
  6. The ejection force is uneven or too large

 

◆ possible causes related to materials

 

  1. Poor stress relaxation of materials
  2. Low yield strength of materials
 
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