The design of the die-casting mold gating system is one of the core aspects of die-casting mold design. Its main content covers the entire process planning from the introduction of molten metal into the mold cavity to the completion of filling, involving the coordinated design of multiple key elements. This design must not only ensure that the molten metal can fill the mold cavity smoothly and efficiently, but also consider pressure transmission, exhaust, temperature control, and subsequent demolding and cleaning. It is a systematic project. Specifically, the gating system design mainly includes the selection of the gating system type, the determination of the structural parameters of each component, the compatibility design with the casting structure, the matching of process parameters, and simulation verification and optimization. Each content directly affects the quality and production efficiency of the die-casting.
First, the selection of the pouring system type is the primary design step and needs to be determined comprehensively based on factors such as the structural shape, size, material properties, and production batch of the casting. For example, for large and complex castings, a multi-runner pouring system may be required to achieve uniform filling; while for small and simple castings, a single-runner pouring system is more economical and efficient. At the same time, the location of the gate (top, bottom, or side) must also be selected in combination with the wall thickness distribution of the casting and the location of important processing surfaces to avoid direct impact of the molten metal on the core or important surfaces and reduce the occurrence of casting defects. In addition, the parameters of the die-casting machine, such as the pressure chamber capacity and clamping force, must also be considered to ensure that the selected pouring system type can match the performance of the die-casting machine and give full play to the efficiency of the equipment.
Secondly, determining the structural parameters of each component is the core of gating system design, including the size, shape, and layout of the sprue sleeve, main channel, branch runners, ingates, overflow troughs, and venting troughs. The inlet diameter and taper of the sprue sleeve must match the die-casting machine’s pressure chamber to ensure smooth and leak-free introduction of the molten metal. The length, taper, and surface roughness of the main channel must be strictly controlled to reduce flow resistance and pressure loss. The cross-sectional shape (circular, trapezoidal, etc.) and dimensions of the branch runner must be determined according to flow distribution requirements to ensure a balanced supply of molten metal to each cavity or ingate. The dimensions of the ingates (width, thickness, and length) directly affect filling speed and pressure transmission and must be precisely calculated based on the thickness of the casting and material fluidity. The location and size of the overflow trough and venting trough are also important. They must be located where the molten metal last arrives and in areas where gas is likely to accumulate to effectively remove gas and cold material.
Compatibility with the casting structure is also a key aspect of gating system design. The gating system’s layout should be closely aligned with the casting’s geometry. For example, for castings with deep cavities, the gating system should guide the molten metal upwards to avoid air entrainment. For thin-walled castings, larger ingates and higher filling speeds are required to prevent premature solidification of the molten metal. Furthermore, the gating system should minimize overlap with critical functional or machining surfaces of the casting to minimize subsequent cleaning and processing. Furthermore, the shrinkage characteristics of the casting must be considered, and appropriate compensation space should be reserved in the gating system design to prevent deformation or cracking due to uneven shrinkage. For example, for alloys with high shrinkage rates, the runners and ingates can be appropriately enlarged to ensure adequate pressure transfer and reduce defects such as shrinkage cavities and porosity.
Finally, matching process parameters and simulation verification and optimization are important means to ensure the rationality of gating system design. The structural parameters of the gating system must match the die-casting process parameters (such as injection speed, injection pressure ratio, mold temperature, etc.). For example, a higher injection speed requires a larger inner gate size to avoid excessive turbulence in the molten metal during flow. With the development of computer technology, numerical simulation has become an important tool for gating system design. By simulating the flow, filling, and solidification of molten metal within the mold cavity, design problems such as eddy currents, air entrainment, and insufficient filling can be identified in advance and targeted optimization can be implemented. Simulation verification can also help designers optimize the structural parameters of each component, shorten the mold trial cycle, reduce development costs, and ensure that the gating system design meets actual production requirements.
