Do injection molds require exhaust?

1, The necessity of exhaust in injection molds
During the injection molding process, molten plastic is injected into the mold cavity under high pressure. Due to the viscosity of plastic and the complexity of the mold cavity, plastic may produce phenomena such as bubbles, trapped air, or burning during the filling process. These phenomena not only affect the appearance quality of the product, but may also reduce its mechanical performance and durability. Therefore, injection molds must be designed with a reasonable exhaust system to ensure that plastic can smoothly fill the mold cavity and avoid the occurrence of the above problems.
2, The principle of exhaust in injection molds
The exhaust principle of injection molds mainly uses the exhaust groove or exhaust hole on the mold to discharge the gas and volatile substances in the plastic inside the mold cavity. When molten plastic is injected into the mold cavity, the gas and volatile substances inside will be pushed towards the exhaust port of the mold. Through the exhaust port, these gases and volatile substances can be quickly discharged, thereby avoiding the formation of bubbles or trapped gas in the mold cavity.
3, Design Points for Exhaust of Injection Mold
The position and quantity of exhaust slots: The exhaust slots should be set at the high and dead corners of the mold cavity to effectively discharge gases and volatile substances. Meanwhile, the number and size of exhaust slots should be designed reasonably based on the size and complexity of the mold cavity.
The shape and structure of the exhaust groove: The shape and structure of the exhaust groove should be conducive to the discharge of gases and volatile substances. Common exhaust groove shapes include straight, curved, and grid shapes. In addition, the depth and width of the exhaust groove also need to be adjusted according to specific circumstances.
Design of exhaust holes: In addition to exhaust slots, exhaust holes can also be installed on the mold. The exhaust hole is usually located on the parting surface of the mold or on the top needle plate of the mold. By adjusting the size and number of exhaust holes, the exhaust effect can be further optimized.
The selection of mold materials: The selection of mold materials also has a certain impact on exhaust performance. Some mold materials with good breathability, such as aluminum alloy, copper alloy, etc., can improve the exhaust performance of the mold.
4, Method for optimizing the exhaust system of injection molds
Increasing the number and area of exhaust slots: By increasing the number and area of exhaust slots, the exhaust capacity of the mold can be improved, reducing the generation of bubbles and trapped air.
Adjust the position and shape of the exhaust groove: Based on the actual situation of the mold cavity, adjust the position and shape of the exhaust groove to make it more in line with the discharge law of gases and volatile substances.
Using mold materials with good breathability: Choosing mold materials with good breathability, such as aluminum alloy, copper alloy, etc., can improve the exhaust performance of the mold.
Optimizing injection molding process parameters: By adjusting process parameters such as injection molding speed, pressure, and temperature, the fluidity of plastics can be improved, and the production of gases and volatiles can be reduced.