company news about The Reasons and Solutions for Uneven Color of Injection Molded Products

  Color inconsistency in injection molded parts is a common quality issue, primarily stemming from inadequate dispersion or unstable processing conditions. The main causes and corresponding solutions are: (1) Poor Colorant/Pigment Dispersion: This often causes streaks or a "mica-like" pattern, especially near the gate. The solution is to use higher-quality masterbatches, ensure proper pre-mixing, or adjust screw design and back pressure for better distributive and dispersive mixing. (2) Thermal Degradation of Polymer or Colorant: Overheating can cause color shifts. Stabilizing the process by strictly controlling and maintaining consistent barrel temperatures, screw speed, and cycle time is crucial. Using thermally stable pigments and polymers is also recommended. (3) Non-Uniform Cooling in Crystalline Plastics: Parts with varying wall thicknesses cool at different rates, leading to differential crystallization and visual color differences. Ensuring uniform cooling through optimized cooling channel design and consistent mold temperature is key. For parts with unavoidable thick sections, using a pigment that masks this effect (like a mica or metallic) can help. (4) Part and Gate Design Influencing Flow: Improper gate location or part geometry can create flow fronts that weld at different pressures or temperatures, causing local color variations (e.g., blush or splay near gates). Modifying the gate design, location, or part geometry to promote more uniform fill and packing can resolve this.