There are many forms of commodity mold gates, but no ma […]
There are many forms of commodity mold gates, but no matter what form of mold gate is used, its opening position has a great influence on the forming performance and molding quality of plastic parts. Therefore, a reasonable selection of the opening position of the mold gate is an important design link to improve the quality of plastic parts. When selecting the gate position of the mold, it is necessary to analyze the flow state of the molten plastic in the mold, the filling conditions and the exhaust conditions according to the geometric characteristics and technical requirements of the plastic manufacturing. The mold gate should be opened at the thickest part of the plastic part. When the wall thickness of the plastic parts differs greatly, if the mold gate is opened in the thin wall, this is the plastic melt enters the cavity, not only the flow resistance is large, but also easy to cool, affecting 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 the latest 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 mold gate should be selected to avoid jetting and creeping. If the small mold gate is facing a cavity with a large width and thickness, when the high-speed material flows through the gate, it will be subjected to high shear stress, which will produce melt fracture phenomena such as jetting and creeping. Sometimes the spray phenomenon will cause the plastic parts to form corrugated flow marks.
The position of the mold gate should be selected to make the plastic flow the shortest and the material flow change direction the least.
The selection of the gate position of the mold should facilitate the discharge of gas in the cavity.
The material flow should prevent the cavity, core and insert from squeezing and deforming.