Why wre Black Lines, Black Streak, and Color-Changing happened?
Main causes : 1. Heat decomposition of resins. 2. Heat decomposition of additives. 3. Volatile gas compressed inside the heated steel barrel. Molding conditions, and injection machines (Solution 1) : 1. Lower the injecting temperature and the mold temperature. 2. Reduce the revolving speed of the screw. 3. Decrease the injecting pressure and the speed. 4. Decrease the backpressure. 5. Remove the residuals inside the screw. Designs in molding products and models (Solution 2) : 1. Set a ventilation opening at the end when resins flow. 2. Correct the gas venting at the welding part. 3. Expand the cold slug. 4. Expand the runner and the gate. Materials (Solution 3) : 1. Dry up fully. 2. Adjust the volume of the lubricant . 3. Increase the volume of the heat stabilizer. 4. Use resins of low volatility.
