Injection molding defects are costly and time-consuming. Understanding their root causes and solutions is essential for maintaining quality production in Chinese mold shops.
| Defect | Appearance | Root Cause | Solution |
|---|---|---|---|
| Flash | Thin excess material at parting line | Clamp force too low, mold wear | Increase clamp force, repair mold |
| Sink Marks | Surface depression near ribs/bosses | Insufficient pack pressure, thick sections | Increase hold time, redesign wall thickness |
| Weld Lines | Visible line where flow fronts meet | Melt temperature too low, poor venting | Raise melt temp, improve venting |
| Short Shot | Incomplete fill | Insufficient injection pressure/volume | Increase injection pressure, check shot size |
| Warpage | Part distortion | Uneven cooling, molecular orientation | Balance cooling, reduce hold pressure |
| Jetting | Snake-like flow marks | Gate size too small, injection speed high | Widen gate, reduce injection speed |
| Burn Marks | Discolored areas | Trapped air, excessive melt temp | Improve venting, reduce injection speed |
| Silver Streaks | Shiny streaks on surface | Moisture in resin, material degradation | Dry material properly, lower barrel temp |
Define and document the operating window for each mold: melt temperature range, mold temperature, injection speed profile, packing pressure and time, cooling time. Products within the window are quality-controlled; outside requires process adjustment.
Contact MFGABC for engineering support, competitive quotes, and fast delivery on injection molding services.
Get a Quote →