There are many forms of daily necessities mould gate, but no matter what form of mould gate is used, its opening position has a great influence on the forming performance and forming quality of plastic parts. Therefore, reasonable selection of mould gate opening position is an important design link to improve the quality of plastic parts. When choosing the location of the mould gate, the geometrical characteristics and technical requirements of plastic manufacturing should be taken into account to analyse the flow state of the molten plastic in the mould, the filling conditions and the exhaust conditions and other factors. Mould gate should be opened in the thickest part of the section of the plastic part. When the wall thickness of the plastic part has a big difference, if the mould gate is opened in the thin wall, this is the plastic melt into the cavity, not only the flow resistance is big, but also easy to cool down, affecting the flow distance of the melt, and it is difficult to ensure that the filling of the whole cavity. The wall thickness of the plastic part is often the latest melt curing place, if the gate is opened in the thin wall, then the wall thickness of the plastic melt shrinkage can not be compensated for the shrinkage and the formation of surface depression or shrinkage holes.
The size and position of the mould gate should be chosen to avoid the production of jetting and creep. If a small mould gate faces a cavity with a large width and thickness, the high speed flow of material through the gate, due to the high shear stress, will produce melt fracture phenomena such as spraying and creep. Sometimes the spraying phenomenon will also make the plastic parts form corrugated flow marks.
Mould gate location should be selected so that the shortest flow of plastic, the least change in the direction of the material flow.
The choice of mould gate location should be conducive to the discharge of gas in the cavity.
The material flow should be prevented from extruding and deforming the cavity, core and insert.
