Cause & Countermeasure: At startup, the melt in the injection molding machine barrel has been heated for a long time, with low viscosity and good flowability, making it prone to flash; after running for a while, the melt continuously carries heat away, resulting in insufficient melt temperature, high viscosity, and poor flowability, leading to underfill. Solution: Gradually increase the barrel temperature after production has been running for a while.

Cause & Countermeasure: After running for a while, the melt continuously carries heat away, causing the melt temperature to drop, viscosity to rise, and flowability to become extremely poor. At this point, pressure and speed alone cannot fill the cavity. Solution: Increase the barrel temperature.

Cause & Countermeasure: Uneven gating causes uneven pressure around the product, leading to oval deformation. Solution: Use three-point gating to ensure uniform injection and pressure distribution.

Cause & Countermeasure: During injection, the high-temperature melt encounters the cold metal insert and cools rapidly, generating extreme concentrated internal stress that leads to cracking. Solution: Preheat the metal inserts before production.

Cause & Countermeasure: Excessively high proportion of sprue regrind, or raw material remaining in the barrel and being heated for too long, leading to thermal degradation and aging. Solution: Increase the proportion of virgin material; regrind should generally be recycled no more than 3 times, and avoid prolonged residence of melt in the barrel.

Cause & Countermeasure: Melt temperature or mold temperature is too low, and injection pressure is insufficient, causing the glass fibers to not be fully encapsulated by the plastic and become exposed. Solution: Increase the melt temperature and mold temperature, and raise the injection pressure.

Cause & Countermeasure: Cold slugs entering the cavity, or dust and impurities mixed into the raw material. Solution: Appropriately increase the nozzle temperature, add a cold slug well, and strengthen dust protection for the raw material.

Cause & Countermeasure: The core pin overheats, causing uneven cooling shrinkage of the product. Solution: Make the core pin from phosphor bronze, which dissipates heat quickly, and add venting in the middle of the mold.

Cause & Countermeasure: Residual internal stress on the product surface, which cracks when attacked by screen printing solvents. Solution: Increase mold temperature to reduce stress, or eliminate internal stress through annealing treatment.

Cause & Countermeasure: Excessively high injection and holding pressure, leaving extreme residual stress at the gate. Solution: Reduce injection and holding pressure, and increase mold temperature.

Cause & Countermeasure: Weld lines (knit lines) exist at the screw bosses, causing insufficient strength. Solution: Increase venting at the mold boss locations, raise mold temperature, and accelerate injection speed to improve weld line strength.

Cause & Countermeasure: Insufficient raw material drying (moisture content), uneven wall thickness (vacuum bubbles), poor mold venting, or raw material decomposition. Solution: Fully dry the raw material, increase mold venting, and optimize the wall thickness structure.