There are many forms of mold gate for daily necessities, but no matter what form of mold gate is used, its opening position has a great impact on the formability and molding quality of plastic parts. Therefore, it is an important design link to reasonably select the opening position of the mold gate to improve the quality of the plastic parts. When selecting the mold gate position, the factors such as the flow state, filling conditions and exhaust conditions of molten plastic in the mold should be analyzed according to the geometric characteristics and technical requirements of plastic manufacturing. The mold gate shall be set at the thickest section of the plastic part. When the wall thickness difference of plastic parts is large, if the mold gate is set at the thin wall, the plastic melt will not only have large flow resistance after entering the cavity, but also be easy to cool, affecting the flow distance of the melt, and it is difficult to ensure that the entire cavity is filled. The wall thickness of the plastic part is often the last place where the melt is solidified. If the gate is set at the thin wall, the surface depression or shrinkage cavity will be formed at the wall thickness because the plastic melt cannot be fed due to shrinkage.
The size and position of the mold gate shall be selected to avoid spray and creep. If the small mold gate is facing a cavity with large width and thickness, the melt fracture phenomenon such as injection and creep will be produced due to the high shear stress when the high-speed material flow passes through the gate. Sometimes the phenomenon of spraying will cause the plastic parts to form ripple flow marks.
The mold gate position shall be selected to minimize the plastic flow and the direction of material flow change.
The gate position of the mould shall be selected to facilitate the discharge of gas in the mould cavity.
The cavity, core and insert shall be prevented from being extruded and deformed by the material flow.
