Because of condensation, a large nu

Because of condensation, a large number of low molecular substances such as water vapor will be produced during the injection molding of thermosetting plastics. At the same time, the original gas in the mold cavity also needs to be excluded from the mold. Therefore, the exhaust gas of the injection mold is much higher than that of the thermoplastic injection mold, and the exhaust gas volume is much larger. The size and position of vent hole or vent clearance shall be designed according to the size of plastic part, and also related to the position of core and insert. The exhaust problem of all kinds of plastic parts should be analyzed according to their forming process. In order to make the exhaust unobstructed, some very small gaps or holes are designed for this purpose. When the exhaust volume of the parts is very small, the parting surface or other mating surfaces of the die can be used for exhaust. If the exhaust is not good, there will be defects such as lack of material and burning at the last full place of the cavity, so it is better to set the exhaust slot there. When the size of the exhaust slot is large, a part of excess plastic can also overflow. This part of plastic is at the front of the material flow and has poor fluidity. It is beneficial to improve the quality of the parts to exclude it. If the overflow occurs at the fusion joint, it is beneficial to improve the fusion strength.