Why does the mold exhaust, so where does the gas come from
Plastic injection molding process often encountered the problem of the top white, black spot, contraction, bubble, silver, flying edge, etc. If after adjust injection molding process parameters, plastic products is still insufficient filling, high internal stress, there are air bubbles, etc. Phenomenon, this is likely to be plastic mold of the exhaust problem.
Just add a little bit of the purpose of the exhaust: burn. The other ten is perfect.Plastic mold venting is not good, the gases in the cavity is compressed, produce a lot of pressure, this is the back pressure to prevent the molten plastic for normal rapid molding, make it difficult to injection molding. Once injection molding difficulty in this case, the researchers often adopt the method of improve the injection pressure of injection, this led to the pressure maintaining prolonged, molding cycle delay, the production efficiency is lower, injection molding machine energy consumption increases and so on. Even corrosive gases are sometimes fouled in the cavity, contaminating plastic molds, reducing the life of the molds and increasing the cost of plastic moulds.
There are several main sources of the gas in injection molding mold: the air in the cavity and the pouring system; The water vapor produced by the evaporation of water from the plastic material. Gases produced by plastic decomposition at high temperature; Gases produced by certain additives in plastics or chemical reactions, such as thermosetting plastics, are often produced by chemical reactions.
