The importance of the air exhaust system in the injection molding process
As an important part of current industrial production, injection molds have emerged many new technologies, and these technologies can provide the efficiency of plastic parts manufacturing, and largely solve the difficulties in the injection process.
The main sources of the air exist in the molding process
1. The air in the empty cavity before injection.
2. Some raw materials are not completely dried, and the water present in the raw materials turns into steam at the high-temperature condition.
3. Due to the high temperature during the injection process, some unstable materials will generate some air or gas into the cavity.
4. Some additives in the raw materials volatilize or react with other substances to generate the gas.
The hazards may happen in the poor exhaust system molds
1. During the injection process, the melted plastic will squeeze the air in the cavity, if the gas and air cannot be removed fully in time, it will cause difficulty in cavity filling, resulting in insufficient volume to fill the cavity.
2. If the gas cannot be removed in time, it will form a high pressure in the cavity and penetrate the plastic under a certain degree of compression, and causing quality defects such as pores in the products.
3. The high pressure caused by gas will lead to a high temperature of the cavity and makes the plastic parts soften, more seriously, resulting in localized carbonization of the plastic parts.
4. Poor air exhaust in the cavity will cause different filling speeds if the melted plastic in each cavity of the multi-cavity mold, and it is easy to form defects such as marks, which reduces the mechanical properties of plastic parts.
5. Due to the hindrance of the gas in the cavity, the filling speed of the cavity is affected, and resulting in a longer production cycle and reduced production efficiency.
