Cross-section design knowledge of injection mold runners

The cross-section design of the injection mold runner is a key step in mold manufacturing, which directly affects the flow of plastic melt, product release and the difficulty of mold manufacturing. Here are some basic things to know about the design of the runner section of the injection mold:

Section shape: The commonly used shapes of shunt sections include trapezoidal, U-shaped, semicircular, circular and rectangular. Various shapes have their own characteristics, such as trapezoidal and U-shaped small workers are easier, while circular cross-section runners have the least resistance, but they need to be combined by slotting on both sides of the moving mold and the fixed mold at the same time. When designing, it is necessary to comprehensively consider the molding performance of the plastic and the processing technology of the mold, as well as the wall thickness of the product, the size of the projection surface and other factors.

Cross-sectional size: The cross-sectional size of the runner should be determined according to the size, wall thickness, plastic variety, injection speed and length of the runner and other factors. For example, for plastics with good flowability, the cross-section of the runner can be smaller; For plastics with poor flowability, the runner cross-section needs to be larger. At the same time, in order to reduce the pressure loss in the flow channel, the cross-sectional area of the flow channel should be increased as much as possible.

Surface Treatment: In order to reduce flow resistance and provide fast mold filling speed, the runner surface must be polished. In addition, the surface roughness of the inner surface of the manifold is Ra1.6.

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