I. Molding quality defects

1. ‌Flying Edge (Shawl)

   ‌Cause: Insufficient clamping force or mold parting surface wear, resulting in melt overflow.

   ‌Countermeasures: Optimize clamping pressure parameters, periodically grind the parting surface or replace the guide pillar guide bush.

2. Shrinkage (dents)

   ‌Reason: Insufficient holding time or irrational design of the cooling system, resulting in uneven shrinkage in thick-walled areas.

   ‌Countermeasures: Extend the holding pressure time, optimize the layout of the cooling water circuit, and install additional follower water circuits if necessary.

3. ‌Fusion marks and bubbles

   Cause: Melt temperature is too low or poor exhaust, especially notable in the molding of complex wire harness connectors.

   ‌Countermeasures: Raise the barrel temperature to the recommended value for engineering plastics (e.g. PC materials need to be pre-dried at 120-150℃), and install additional exhaust tanks or vacuum-assisted exhaust.

II. Structural damage to the mold

1. Difficulty with sprue release

   ‌Reason: Insufficient finish of the conical hole of the sprue sleeve (Ra>0.4μm) or failure of the pulling rod

   ‌Countermeasure: Adopt standard sprue parts, regularly grind the cone hole and configure double ejector mechanism.

2. ‌Dynamic/Stationary Mold Offset‌

   Reason: The self-weight of the large mold leads to uneven force on the guide pillar, and the perpendicularity of the guide pillar hole is super poor (>0.02mm/m).

   ‌Countermeasure: Adopt one-time boring process after the dynamic and fixed molds are combined, and add a cylindrical positioning key (diameter ≥20mm) during processing.

3. ‌Top bar breaks and leaks‌

   Reason: Uneven force on ejector system or insufficient strength of ejector rod material (recommended SKD61 heat treatment HRC50-55).

   Countermeasures: Optimize the density of top bar layout (spacing ≤ 50mm) and adopt stepped top bar structure.

III. Process Stability Issues

1. ‌Loss of dimensional accuracy‌

   ‌Reason: Mold temperature fluctuation (±2℃ or more) or material shrinkage calculation deviation (e.g. PA66 shrinkage 1.5-2.5%).

   Countermeasure: Adopt mold temperature controller to control temperature accurately (±0.5℃), and correct the shrinkage compensation value through Moldflow simulation.

2. ‌Hot runner system abnormality‌

   Cause: Localized failure of the heating coil or blockage of the hot nozzle, resulting in uneven melt temperature.

   ‌Countermeasures: Configure multi-point temperature monitoring system and dismantle and clean the heat nozzle regularly (cycle ≤ 50,000 mold times).

IV. Maintenance management difficulties

1. ‌Accelerated life decay‌

   ‌Reason: Abrasive wear of engineering plastics (e.g. PPS with 40% fiberglass) on the cavity (wear rate > 0.01mm/ 10,000 die times).

   Countermeasures: Use TD treatment or DLC coating (thickness of 3-5μm), and establish a mold use file to track maintenance cycles.

2. Sudden card mode‌

   Cause: Lubrication failure of the slider mechanism or intrusion of foreign matter (probability of occurrence about 0.3-0.5%).

   ‌Countermeasures: Configure automatic lubrication system (oil injection interval ≤ 500 mold times), install mold protection sensor.

V. Design optimization directions

• ‌Modular design: Standardization of electrodes, sliders and other components (module reuse rate increased by more than 30%), shortening the development cycle.

• ‌Intelligent monitoring: integrated pressure/temperature sensor (sampling frequency ≥100Hz), realizing abnormal real-time warning.