Why must injection mold set exhaust system?

The role of the exhaust system in the injection mold is to remove the gas generated during the injection molding process and prevent excessive pressure. When plastic raw materials are injected into the mold, they may be wrapped in air or produce gas due to high temperature, and if these gases can not be discharged in time, it will lead to an increase in the pressure inside the mold, which will affect the quality and performance of the product. In addition, if the pressure inside the mold is too high, it may also lead to mold damage, increasing the cost of maintenance and replacement.

Poor exhaust of injection mold will bring a series of hazards to the quality of plastic parts and many other aspects. The main manifestations are as follows:

1. In the injection molding process, the melt will replace the gas in the mold cavity. If the gas is not discharged in time, it will cause the melt filling difficulty, resulting in insufficient injection amount and not being able to fill the mold cavity.

2. The gas that is not smooth will form high pressure in the cavity and penetrate into the plastic at a certain degree of compression, resulting in quality defects such as pores, void, loose tissue and silver lines.

3. Because the gas is highly compressed, the temperature in the cavity rises sharply, which causes the surrounding melt to decompose and burn, making the plastic parts appear local carbonization and burning. It mainly appears at the confluence of the two melts, the main Angle and the flange of the gate.

4. The exclusion of gas is not smooth, which makes the melt speed into each cavity different, so it is easy to form flow marks and fusion marks, and reduce the mechanical properties of plastic parts.

5. Due to the obstruction of gas in the cavity, the filling speed will be reduced, the molding cycle will be affected, and the production efficiency will be reduced.

In order to ensure the normal operation of the injection mold and the quality of the product, it is necessary to set the exhaust system. The design of the exhaust system should be based on the specific situation of the mold, such as the structure of the mold, the characteristics of the plastic raw materials, and the parameters of the injection machine. In general, the design of the exhaust system should have the following requirements:

1. Good air flow rate to ensure smooth gas discharge;

2. The position and number of exhaust holes are reasonable, which can cover all parts of the mold;

3. The size of the exhaust hole is moderate, which can ensure the discharge of gas without causing the leakage of raw materials;

4. The exhaust system is simple in structure and easy to maintain and replace.

In practical applications, the design of the exhaust system also needs to consider the requirements of environmental protection. For example, recycling pipes can be set up to collect the discharged gas and recycle it to reduce the impact on the environment.