In order to let the plastic mold be damaged or abnormal […]
In order to let the plastic mold be damaged or abnormal after injection molding, we need to perform certain specifications on the mold injection molding, and its main requirements meet the following six conditions:
1. Turn off the mold pressure: in principle, it should be greater than the total pressure of the plastic injection into the mold, with no flash as the reference.
2. Part of the same relationship between pressure and speed acts on the mold. The purpose is to make the raw materials enter the mold uniformly, thoroughly, and adequately fill all corners. Too low will short shot, shrink, too high with hair, too full, sticky Mold, scorch, vulnerable mold and high internal stress and other undesirable phenomena.
3. Speed: The speed of the material determines the condition of the raw material in the mold runner and in the finished product. It has burrs, overfilling, scorching, slow shot, shrinkage, and poor combination.
4. Temperature: Different raw materials, different temperatures, too low solution glue color unevenness, internal stress of the product increases. Because the temperature is too low and the pressure is too high, it may cause the screw to break, too high, the product has burrs, and it is produced due to cooling The temperature difference causes shrinkage. The raw materials will decompose, turn yellow, change color, and break easily. The cooling time becomes longer, the gas is not easy to discharge, and there will be gas.
5. Back pressure: The resistance of the screw to retreat when rotating and feeding is called back pressure. Its function makes the raw material more compact in the transportation and compression. It can make the air and water of the raw material be discharged from the screw. The sol does not affect the surface of the finished product. The gas composition is low. There will be bubbles on the surface and silver streaks on the surface. High temperature will cause overheating, agglomeration, overflowing, long cycle, and the screw will not retreat. At the same time, the application of loose retraction is very important: when the back pressure is low, some raw materials should be retreated, there is It is not necessary (adjust the back pressure according to various materials of different properties). When the back pressure is high, it is necessary to use the back and pay attention to the distance without interfering with the air and the glue.
6. The temperature of the mold and the length of the cooling time affect the viscosity of the finished product, shrinkage, dimensional tolerance, surface brightness, cycle, etc., and should be adjusted in time according to the actual situation. Another acrylic, PC, such as the thickness of the finished product should be The mold temperature will not cause bubbles and stress.