1. Surface Film Formation: A white or gray spreading effect on the product's surface caused by additives in the resin flowing over it. The main cause is the additives within the resin, and excessive stress from injection molding conditions can also trigger this issue.
2. Excessive Flash: Thin, unwanted flanges forming along the edges of the plastic part. This is primarily caused by poor mold closure, large gaps, excessive plastic flowability, or too much material being injected.
3. Low Transparency: The phenomenon of reduced transparency in transparent products like PPS, SAN, etc. Causes include excessive use of release agents, contamination by other resins, mixing with incompatible resins, poor mold processing conditions, or improper mold temperatures.
4. Color Fading or Discoloration: When the color of the product differs from the intended standard color. This can be caused by color mixing mistakes, resin contamination, excessive use of recycled materials, contamination from the injection molding machine, or thermal degradation of the resin.
5.Surface ripples: This term lacks a precise definition, but generally refers to the undulation of the melt on the mold cavity surface in a semi-solid state, or stagnant melt flow.
6.Incomplete plastic part: This occurs when the mold cavity is not fully filled, resulting in an incomplete or deformed plastic part. Main causes include insufficient material supply, poor melt flowability, excessive gas injection, or poor venting.
7.Black spots and streaks: Black lines appear on the surface of the plastic part. This may be due to the use of volatile lubricants or mold release agents, resin thermal degradation, the use of black pigments, incomplete cleaning of the injection molding machine, or contamination during processing.
8.Dimensional instability: This refers to inconsistent and fluctuating dimensions of the plastic part. Causes may include insufficient mold strength or rigidity, poor precision, unstable injection molding machine operation, or frequent changes in molding conditions.
9.Sinks and bubbles: Although lacking a precise definition, these problems are often caused by poor pressure holding or insufficient shrinkage compensation, uneven cooling of the plastic part, inconsistent wall thickness, or excessive shrinkage.
10. Silver streaks: These are silvery-white needle-like or mica-like streaks or spots on the surface of plastic parts, usually distributed along the material flow direction (sometimes also called "watermarks"). Causes include excessively high material moisture content, the presence of low-volatility substances, air bubbles, poor venting, insufficient injection pressure, or excessively low mold temperature.
11. Weld lines: These are marks or lines formed at the junction of material flows. Causes are usually improper weld line location, insufficient fluidity, residual air or volatile substances in the mold, or problems with the mold release agent or colorant.
12. Cracks and fractures: These are small cracks or fractures on the surface of plastic parts, especially near the gate. Causes are usually excessive internal stress, poor ejection during demolding, uneven cooling, or foreign matter contamination.
The above is a summary of injection molded part defects and their core causes by XPMold. For in-depth discussions on solutions or to learn more about our precision mold accessories, please feel free to contact us!
