1. Injection Molding Process Parameters

• Underinjection pressure

• Cause: Hydraulic component failures in the injection system, like oil pump wear or valve leakage, can prevent the injection pressure from reaching the set value. A poorly - sealed injection cylinder also affects pressure. Incorrectly set low injection pressure due to insufficient understanding of product requirements and plastic material characteristics can lead to melt being unable to fill complex - shaped mold parts.

• Solution: Test the injection system pressure with professional equipment and repair or replace faulty components. Adjust the injection pressure reasonably, referring to material data and test molds. Regularly check the injection cylinder's seal and replace worn seals.



• Slow injection rate

• Cause: The injection speed setting is related to product wall thickness and process length. Control system failures in the injection molding machine can also slow down the speed. Small mold gate size or narrow flow path diameter can limit the injection speed.

• Solution: Adjust the injection speed according to the product, check and repair the control system, and optimize the mold gate and runner design.

• Insufficient pressure retention or short retention time

• Cause: Incorrect pressure setting or hydraulic component failures in the pressure - holding system can lead to insufficient melt compensation during cooling. A too - short pressure - holding time or improper switching point can also cause lack of material.

• Solution: Check and readjust the pressure - holding system pressure, extend the pressure - holding time reasonably, and optimize the pressure - holding switch point settings.

  
  

  

• Low melt temperature

• Cause: Incorrect cylinder heating temperature setting, heating element failures, or the plastic staying in the cylinder for too long can result in a low melt temperature.

• Solution: Set the cylinder heating temperature properly based on plastic material characteristics, check and maintain heating elements, and optimize the injection molding process to reduce plastic residence time in the cylinder.

2. Mold - related Aspects

• Small or blocked gate

• Cause: A too - small gate size in mold design or blockage by impurities during injection molding can reduce melt flow rate.

• Solution: Determine the gate size reasonably during mold design. Clean blocked gates in time and add filters to keep the environment clean.

• Unreasonable runner system design

• Cause: Excessive runner length, small diameter, rough surface, or uneven temperature control in the hot runner system can increase melt flow resistance.

• Solution: Shorten the runner length, optimize the diameter, polish the runner, and regularly check and optimize the hot runner system.

• Poor exhaust

• Cause: Inadequate air discharge in the cavity due to unreasonable exhaust design or improper injection process parameters can lead to lack of material.

• Solution: Design exhaust channels reasonably, use breathable materials if possible, and optimize injection process parameters. For complex molds, consider vacuum exhaust.

3. Plastic Raw Materials

• Poor plastic flow

• Cause: High - viscosity plastics, plastic humidity, and uneven particle size and shape can affect plastic flow.

• Solution: Choose plastics with good flow, dry water - absorbent plastics fully, and screen or replace raw materials with uneven particles.

4. Equipment

• Screw wear

• Cause: Long - term use can wear the screw, affecting plastic plasticization and transportation, and thus product molding quality.

• Solution: Regularly check screw wear, replace the screw when necessary, select wear - resistant screw materials, and avoid abnormal operating conditions.

• Cylinder wear or uneven temperature

• Cause: Cylinder inner wall wear can change melt flow, and heating system failures can lead to uneven temperature and incomplete plasticization.

• Solution: Check and repair or replace the worn cylinder, calibrate temperature sensors, and maintain the heating system.