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What are the basic conditions for the processing of plastic injection parts

Update:24-01-2022
Summary:

The first is to close the molding, which is a very impo […]

The first is to close the molding, which is a very important indicator. In principle, it should be greater than the total pressure of the plastic injection into the mold, based on the absence of burrs. Off-molding is a real reference factor and one of the basic conditions for plastic injection molding. Good molding adjustment is also a good thing for injection molding.
Generally speaking, pressure and velocity have partially the same relationship acting in the mold. It also has a certain effect on the mold. The purpose is to make the raw materials enter the mold uniformly and fill every corner with an appropriate amount. If it is too low, it will cause short shots and shrinkage. If it is too high, there will be burrs, oversaturation, mold sticking, scorching, vulnerable molds, and high internal stress. Only the right pressure and speed can make the filling reach an ideal state.
I believe that everyone has a certain understanding of speed. The speed of speed determines the condition of the raw material in the mold runner and the finished product. Similarly, if it is fast, there will be burrs, oversaturation, and burning. If it is slow, there will be short shots, shrinkage, poor bonding, and easy to break. Therefore, we need to adjust the parameters, and then do further consideration to optimize the speed to a suitable state.
Different temperatures will bring different experiences. The raw materials are different and the temperature is different. If the temperature is too low, the color of the solution glue will be uneven, and the internal stress of the finished product will increase. If the temperature is too low and the pressure is too high, the screw may break. If the temperature is too high, the product will have burrs, and a temperature difference will be generated due to cooling, causing shrinkage. We know that raw materials will decompose, turn yellow, discolor, and break easily. If in this process, the cooling time becomes longer, the gas is not easy to be discharged, and there will be gas.
A common factor: is backpressure. The resistance of the screw to retreat when rotating and feeding is called backpressure. Its function makes the raw material more compact in conveying and compression. The air and water of the raw material can be discharged from the back of the screw. So that the sol does not contain gas components that affect the surface of the finished product. When the pressure is low, there will be bubbles and silver streaks on the surface. High pressure will cause overheating, agglomeration, overflow of glue, long cycle, and the screw will not retreat. Therefore, it is important to ensure that the back pressure is neither too high nor too low, and the application of loosening is very important: when the backpressure is low, some raw materials need to be loosened, while others are not. When the backpressure is high, be sure to use the loose back and pay attention to the distance between the air and the overflow of glue. This is backpressure.
The temperature of a mold and the length of the cooling time will affect the sticking, shrinkage, dimensional tolerance, surface brightness, cycle, etc. of the finished product. These conditions should be adjusted according to the actual situation. In addition, acrylic and PC, such as the finished product, must have a mold temperature when the meat is thick, so that bubbles and stress will not be generated. So how much temperature is needed to make the finished product unaffected? The conditions for the processing of plastic injection molded parts are as described above and are already very clear. In the injection molding plant, there are many factors that restrict the smooth molding of the product.