Mold processing will use a variety of equipment, will do a variety of preparations, but there is a more important, is the need for exhaust in the process of processing, the following will tell you why to exhaust.
1、 Gas sources in injection molding
1. When pouring the mold, there is a lot of hot air which can not be exhausted, resulting in air inside;
2. Some raw materials have more water in them, and become steam under high temperature;
3. The gas produced by the high temperature decomposition of some unstable plastics in the process of injection molding;
4. All kinds of chemical substances fuse to produce chemical reaction, which is also easy to produce gas;
2、 Harm of poor exhaust
Poor exhaust of injection mold will bring a series of harm to the development of many problems such as the quality of plastic parts. The main work forms are as follows:
1. During the injection process, the melt will change the gas in the cavity. If the gas is not discharged in time, it will lead to molten filling, resulting in insufficient injection, unable to fill the cavity.
2. If there is too much gas and the die is not cooled, the high pressure formed by the gas is easy to deform the inner part of the die, resulting in the quality reduction of the die;
3. Because the gas is highly compressed, the temperature in the cavity rises sharply, resulting in the decomposition and burning of the surrounding melt, and the local carbonization and burning of the plastic parts. It mainly occurs at the confluence of two melts, * angle and gate flange.
4. The gas emission is not free, so that the melt into the cavity at different speeds, easy to form flow marks and melt marks, reduce the mechanical properties of plastic parts.
5. Due to the sudden change of gas in the cavity, it will reduce the full speed, affect the molding cycle and reduce the productivity.