（34） Gloss Variations on textured surfaces Injection Molding Process Defect Handling Manual Injection Molding Process Defect Handling Manual

1. Apparent Although the mold has a uniform surface material, the surface of the product still exhibits gray and uneven gloss.
Physical causes
The surface of the product produced by injection molding is somewhat a replica of the mold surface. Surface roughness depends on the thermoplastic material itself, its viscosity, speed settings, and molding parameters such as injection speed, packing, and mold temperature. As a result, due to the surface roughness of the imitation, the surface of the product may appear gray, darker, or smooth.
Theoretically, when the surface of a mold that has been pitted or eroded has been accurately modeled, the light projected onto the surface of the product will diffuse. Therefore, dark areas appear on the surface. For surfaces with less precise imitation, the diffuse reflection phenomenon will be controlled, resulting in a good gloss effect on the surface of the product
The causes and improvement measures related to processing parameters are shown in the following table:
1. Pressure maintaining too low to increase pressure maintaining pressure
2. The pressure holding time is too short, increasing the pressure holding time
3. The mold wall temperature is too low to increase the mold wall temperature
4. The melt temperature is too low to increase the melt temperature
The reasons and improvement measures related to the design are shown in the table below:
1. The difference in mold wall section is too large to provide a more uniform mold wall section
2. Excessive material accumulation or edge size to avoid excessive material accumulation or edge size
3. Poor exhaust at the material flow line improves mold exhaust at the material flow line