When processing molds, you must grasp the exhaust matters

2021-03-23 15:38:13 admin

When processing molds, you must grasp the exhaust matters




When processing molds, various equipment will be used and various preparations will be made. However, one of the more important ones is the need to exhaust during the processing. The following will tell you why it is necessary to exhaust.




1. The source of gas in injection molding




1. When pouring the mold, there is air in the interior due to too much heat and incomplete emission;




2. There is a lot of moisture inside some raw materials, which will become water vapor under high temperature blessing;




3. Gas generated by high temperature decomposition of certain unstable plastics during injection molding;




4. The fusion of various chemical substances produces chemical reactions and easily generates gas;




2. Harm of poor exhaust




Poor venting of the injection mold will bring a series of harms to the development of many problems such as the quality of plastic parts. The main work manifestations are as follows:




1. During the injection molding process, the melt will replace the gas in the cavity. If the gas is not discharged in time, it will cause melt filling, resulting in insufficient injection and failure to fill the cavity.




2. If there is too much gas and the mold is not cooled, the high pressure formed by the gas will easily deform the inside of the mold and cause the quality of the mold to decrease;




3. Because the gas is highly compressed, the temperature in the cavity rises sharply, causing the surrounding melt to decompose and burn, and the plastic parts are locally carbonized and burnt. It mainly appears at the confluence of two melts, the * corner and the gate flange.




4. The gas is not freely discharged, which makes the speed of the melt enter the cavity different, which is easy to form flow marks and melt marks, and reduce the mechanical properties of the plastic parts.




5. Due to the sudden change of the gas in the cavity, it will reduce the full speed, affect the molding cycle, and reduce the productivity.