The selection of the die-casting mold parting surface is a crucial step in die-casting mold design, directly impacting casting quality, production efficiency, and mold life. As the interface between the movable and fixed molds, the proper selection of the parting surface requires comprehensive consideration of multiple factors, including the casting’s structural shape, dimensional accuracy, and molding process requirements. Improper parting surface selection can result in flash, excessive burrs, and even defects such as insufficient die-casting and deformation, increasing the difficulty and cost of subsequent processing.
When considering the casting structure, the parting surface should be located at the largest cross-section of the casting. This ensures smooth demolding during mold opening and avoids mold jamming caused by excessive cross-sectional variations. For example, for castings with complex internal cavities or bosses, the parting surface needs to be located where it can smoothly separate the mold cavity while ensuring that the critical dimensions and accuracy of the casting are not affected by the parting surface’s location. Furthermore, the parting surface should be selected so that it does not overlap with key machined surfaces of the casting to minimize the impact of flash on the accuracy of these surfaces and reduce the workload of subsequent polishing and finishing.
From a molding process perspective, the position of the parting surface affects the flow and filling of the molten metal within the mold cavity. A properly designed parting surface guides the molten metal to smoothly and evenly fill the entire cavity, minimizing problems such as eddy currents and air entanglement. Improper parting surface placement can hinder the flow of the molten metal, leading to pressure loss and compromising the density and mechanical properties of the casting. Furthermore, the selection of the parting surface should also consider venting to ensure that gases within the cavity can be smoothly discharged, thus avoiding defects such as porosity and shrinkage in the casting.
The mold’s processing and maintenance costs are also key considerations when selecting parting surfaces. The shape of the parting surface should be as simple and regular as possible, avoiding overly complex curves or slopes to reduce the difficulty and cost of mold processing. For example, a flat parting surface is easier to process than a curved one, reducing the time and cost of milling, grinding, and other processing steps. Furthermore, the location of the parting surface should facilitate mold assembly and maintenance, allowing for quick disassembly and replacement of parts in the event of wear or failure during use, thereby improving mold maintenance efficiency.
Finally, the selection of the parting surface must also be compatible with the die-casting machine’s parameters, such as clamping force and mold opening stroke. Ensure that the position and shape of the parting surface do not affect the machine’s normal operation while fully utilizing the machine’s performance to improve production efficiency. For example, the projected area of the parting surface should be compatible with the machine’s clamping force to avoid flashing during the die-casting process due to insufficient clamping force. In summary, selecting the die-casting mold’s parting surface is a complex process that requires comprehensive consideration of multiple factors. Only by making the right choice can the quality of the casting and smooth production be guaranteed.
