Why Surface Hazing Occurs During Injection Molding
Surface hazing during injection molding primarily results from issues related to mold design, process parameters, or material quality. These factors prevent the product surface from achieving a smooth and transparent appearance.
1. Material Issues
Causes:
Excess moisture or volatile impurities in the raw material decompose at high temperatures, forming gases or fine particles that deposit on the product surface.
Insufficient material purity or poor melt flow characteristics.
Solutions:
Use drying equipment to thoroughly dry the raw material, especially for moisture-sensitive materials such as PC and PA.
Select high-quality, high-purity raw materials, and add appropriate additives.
2. Mold Design Issues
Causes:
Inadequate polishing of the mold surface or surface defects prevents the formation of a smooth finish on the product.
Uneven or insufficient cooling in the mold leads to residual stress or gasification on the product surface.
Solutions:
Enhance the polishing grade of the mold surface to ensure it meets design requirements for smoothness.
Optimize the mold cooling system to ensure uniform temperature distribution and avoid localized overheating or insufficient cooling.
3. Injection Molding Process Parameters
Causes:
Improper injection temperature or pressure settings cause incomplete melting of the raw material or thermal degradation.
Excessive injection speed prevents adequate gas evacuation, adversely affecting surface quality.
Insufficient holding time results in incomplete filling, compromising the surface structure.
Solutions:
Adjust injection temperature, pressure, and speed to ensure the raw material melts adequately and fills the mold cavity smoothly.
Increase the holding time to ensure the product's surface and internal structure are fully formed.
Inspect the venting system and add venting grooves or air vents as necessary.
