In order to make any damage or abnormality after the injection moulding of the plastic mould, we need to carry out certain specifications for the injection moulding of the mould, and its main requirements meet the following six conditions:
1. mould closing pressure: In principle, it should be greater than the total pressure of the plastic injection into the mould, based on no burrs.
2. Pressure and speed have some of the same relationship to act in the mould. The purpose is to make the raw materials into the mould can be uniform, thorough, and appropriate to fill all corners. Too low will shoot short, shrink, too high hairy, full, sticky mould, burnt, vulnerable mould and high internal stress.
3. Speed: The speed determines the condition of the raw material in the mould runner and in the finished product. It has burrs, oversaturation, and scorching. When it is slow, short shots, shrinkage, and poor combination are easy to break.
4.Temperature: Different raw materials, different temperatures, too low solution gel color unevenness, increased internal stress of the finished product. Because the temperature is too low, the pressure is too high, it may cause the screw to break, too high, the product has burrs, and it is caused by cooling. The temperature difference causes shrinkage. The raw materials will decompose, turn yellow, change color, and easily break. The cooling time becomes longer, the gas is not easy to be discharged, and there will be gas.
5.Back pressure: The resistance of the screw to retreat when it is rotated is called back pressure. Its role makes the raw material more compact in the conveying and compression. It can make the air and water of the raw material be discharged from the back of the screw. So that 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 will overheat, agglomerate, glue overflow, long cycle, and the screw will not retreat. At the same time, the application of loosening is very important: when the back pressure is low, some raw materials will loosen. It is not necessary to adjust (more than the back pressure according to various raw materials of different properties). When the back pressure is high, it is necessary to use loosening and pay attention to the distance from the air and the glue.
6.The temperature of the mould and the length of the cooling time affect the finished product’s sticky mould, shrinkage, dimensional tolerance, surface brightness, cycle, etc., and should be adjusted in a timely manner according to the actual situation. In addition, acrylic, PC, such as the thickness of the finished product must have mould temperature will not produce bubbles and stress.