Solutions for Molding Defects (Silver Streaks)

Silver streaks are a phenomenon in which shining line shaped patterns appear on the surface of the molded product. These can be considered external appearance quality defects in exterior parts of consumer electrical products, automobiles, motorcycles, etc.
The cause of silver streaks is the air or gases contained in the molding material appearing on the surface of the molded product.
The following methods can be thought of as the countermeasures for solving the problem of silver streaks.

(1) Countermeasures related to molds1. Enhancing the function of air vents.
2. Making gate size larger.
3. Making the cold slag well larger

(2) Countermeasures related to the injection molding conditions1. Checking the preliminary drying conditions (temperature, drying time) of the molding material, and carrying out appropriate drying.
This is the most important countermeasure.
2. Making the injection speed lower and filling the cavity slowly.
3. Making the cylinder temperature lower.
4. Making the screw rotation speed lower.
5. Preventing stagnation of the plastic inside the cylinder.

(3) Countermeasures related to the molded product design1. Making the wall thickness of the molded product as uniform as possible.