How to determine the position of the inner gate in an aluminum alloy die casting mold

The selection of the position of the inner gate is the first issue to be considered when designing the gating system. When determining the position of the inner gate, it is necessary to comprehensively consider factors such as the structural characteristics of the die casting, wall thickness, shrinkage deformation, alloy type, characteristics of the die casting machine, mold parting, and service performance of the die casting. It is necessary to analyze the flow state of liquid metal during filling, changes in filling speed, and predict possible dead corners, air entrapment, and cold shut off locations during the filling process, in order to arrange suitable overflow and exhaust systems.

When selecting the location of the inner gate, the following principles should generally be considered:

(1) It is conducive to the transmission of injection pressure, so the internal gate is generally arranged at the thick wall of the die casting. (2) It is beneficial for the exhaust of the mold cavity. After entering the mold cavity, the metal liquid should first fill the deep cavity where it is difficult to exhaust, and it is not advisable to immediately close the parting surface, overflow groove, and exhaust groove, otherwise it may cause poor exhaust.

(3) The metal liquid flowing into the mold cavity should minimize twists and turns to avoid excessive eddy currents and reduce entrapment gas; The process should be as short as possible to reduce the heat loss of the liquid metal.

(4) After liquid metal enters the mold cavity, it is not advisable to directly impact the core or wall. In particular, it is important to avoid impacting small and thin cores or threaded cores to reduce kinetic energy loss and prevent erosion and mold sticking.

(5) Minimize the diversion of liquid metal in the mold cavity. "When the metal liquid divides and then flows together, it will impact each other, producing defects such as eddy currents, air entrapment, and oxidation slag inclusions, and causing cold joint marks at the junction, affecting the strength and surface quality of the area.". If necessary, an overflow groove should be provided at the confluence to guide the low-temperature metal liquid at the front of the liquid flow into the overflow groove, to avoid cold shuts or cold joint marks at this location, and to improve the strength of this location. At the same time, it can also improve the mold temperature at the confluence location, making the mold temperature evenly distributed.

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How to determine the position of the inner gate in an aluminum alloy die casting mold - ENchuang Technology

Return to the list Source: Industry News Release Date: March 14th, 2023 Views: 12

The selection of the position of the inner gate is the first issue to be considered when designing the gating system. When determining the position of the inner gate, it is necessary to comprehensively consider factors such as the structural characteristics of the die casting, wall thickness, shrinkage deformation, alloy type, characteristics of the die casting machine, mold parting, and service performance of the die casting. It is necessary to analyze the flow state of liquid metal during filling, changes in filling speed, and predict possible dead corners, air entrapment, and cold shut off locations during the filling process, in order to arrange suitable overflow and exhaust systems.

When selecting the location of the inner gate, the following principles should generally be considered:

(1) It is conducive to the transmission of injection pressure, so the internal gate is generally arranged at the thick wall of the die casting. (2) It is beneficial for the exhaust of the mold cavity. After entering the mold cavity, the metal liquid should first fill the deep cavity where it is difficult to exhaust, and it is not advisable to immediately close the parting surface, overflow groove, and exhaust groove, otherwise it may cause poor exhaust.

(3) The metal liquid flowing into the mold cavity should minimize twists and turns to avoid excessive eddy currents and reduce entrapment gas; The process should be as short as possible to reduce the heat loss of the liquid metal.

(4) After liquid metal enters the mold cavity, it is not advisable to directly impact the core or wall. In particular, it is important to avoid impacting small and thin cores or threaded cores to reduce kinetic energy loss and prevent erosion and mold sticking.

(5) Minimize the diversion of liquid metal in the mold cavity. "When the metal liquid divides and then flows together, it will impact each other, producing defects such as eddy currents, air entrapment, and oxidation slag inclusions, and causing cold joint marks at the junction, affecting the strength and surface quality of the area.". If necessary, an overflow groove should be provided at the confluence to guide the low-temperature metal liquid at the front of the liquid flow into the overflow groove, to avoid cold shuts or cold joint marks at this location, and to improve the strength of this location. At the same time, it can also improve the mold temperature at the confluence location, making the mold temperature evenly distributed.

(6) Internal gates are not suitable for parts on die castings that require high accuracy and surface roughness and are not machined.

(7) The setting of the inner gate should consider the distribution of the mold temperature field in order to ensure good filling at the distal end.

(8) The inner gate aggregate should be easy to cut and clean, taking into account the impact of removing the inner gate on the die casting.

(9) Select the appropriate inner gate for die castings with different structural characteristics:

① For complex thin-walled die castings, it is advisable to use a thinner inner gate to ensure a higher filling speed; For die castings of general structure, it is advisable to use a thicker inner gate to ensure a smooth flow of liquid metal, which is conducive to pressure transmission and exhaust For complex die castings, the inner gate should be located as far as possible in the center of the mold cavity of the die casting, so that the situation of liquid metal filling is always better than the setting of the inner gate on the side.

③ For die castings with large rib surfaces, the internal gate should be set to allow the liquid metal to flow in the direction of the rib to avoid creating streamlines and incomplete ribs.

① For narrow and long die castings, the inner gate should be set at the end instead of introducing liquid metal from the middle to prevent vortices and entrapment of gas.

⑤ For tubular and simple die castings, it is best to set an annular inner gate at the end to form a good filling state and exhaust conditions.