There are many forms of die gate positions, but no matter what form of die gate is used, its opening position has a great influence on the forming performance and quality of plastic parts. Therefore, a reasonable selection of the opening position of the die gate is an important design link to improve the quality of plastic parts. When selecting the gate position of the die, it is necessary to analyze the flow state of the molten plastic in the die, the filling conditions and the exhaust conditions according to the geometric characteristics and technical requirements of the plastic manufacturing.

The die gate should be opened at the thick section of the plastic part. When the wall thickness of the plastic part differs greatly, if the die gate is opened in the thin wall, it is difficult for the plastic melt to flow into the cavity, not only the flow resistance is large, but also easy to cool, which affects the flow distance of the melt. It is easy to ensure that the entire cavity is filled. The wall thickness of the plastic part is often the place where the melt is late to solidify. If the gate is opened in the thin wall, the wall thickness will form a surface depression or shrinkage due to the shrinkage of the plastic melt.

The size and position of the die gate should be selected to avoid jetting and creeping. If the small die gate is facing a cavity with a large width and thickness, when the high-speed material flows through the gate, due to high shear stress, it will produce melt fracture phenomena such as jetting and creeping. Sometimes the spray phenomenon will cause the plastic parts to form ripple flow marks.

The location of the die gate should be selected so that the plastic flow is short and the material flow changes less direction.

The selection of the gate position of the die should facilitate the discharge of gas in the cavity. Should prevent the material flow from squeezing and deforming the cavity, core and insert.

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