理論上說，尼龍塑料件加工當被點蝕或侵蝕過的模具表面已精確仿制，投射到制品表面的光線會發生漫反射。因此，表面會出現黯區。對具有較少精確仿制的表面，漫反射現象就會得到控制進而制品表面出現好的光澤效果

與加工參數有關的原因與改良措施見下表：

1、保壓太低 提高保壓壓力；

2、保壓時間太短 提高保壓時間；

3、模壁溫度太低 提高模壁溫度；

4、熔料溫度太低 提高熔體溫度；

與設計有關的原因與改良措施見下表：

1、模壁截面差異太大 提供更均一的模壁截面；

2、材料積留過多或棱邊尺寸過大 避免材料積留過重或棱邊尺寸過大；

In theory, when the surface of the mold that has been pitting or eroded during the processing of nylon plastic parts has been accurately replicated, the light projected onto the surface of the product will undergo diffuse reflection. Therefore, there will be dark areas on the surface. For surfaces with less precise replication, diffuse reflection phenomenon will be controlled, resulting in a good gloss effect on the surface of the product

The reasons and improvement measures related to processing parameters are shown in the following table:

1. Raise the holding pressure if it is too low;

2. If the holding time is too short, increase the holding time;

3. Raise the mold wall temperature if it is too low;

4. Raise the melt temperature if the melt temperature is too low; The reasons and improvement measures related to design are shown in the following table:

1. The significant difference in mold wall cross-section provides a more uniform mold wall cross-section;

2. Excessive material accumulation or large edge size should be avoided to prevent excessive material accumulation or large edge size;