The design of automotive die-casting molds is a key link in the automotive manufacturing industry chain, directly affecting the quality, production efficiency, and manufacturing costs of die-castings. There are many types of automotive die-castings, including engine blocks, transmission housings, steering knuckles, door frames, and more. These parts are not only complex in shape, but also need to withstand complex working conditions such as high temperature, high pressure, and vibration, thus placing extremely high demands on mold design. At the beginning of the design process, a comprehensive analysis of the structural characteristics, performance requirements, and production batch size of the parts is required. In combination with the characteristics of the die-casting process, a reasonable mold design plan should be formulated. For example, die-castings such as engine blocks have uneven wall thickness and complex internal cavities. Mold design must focus on the filling path of the molten metal and the exhaust effect to avoid defects such as pores and shrinkage. Exterior parts such as door frames, on the other hand, have higher requirements for the mold’s surface accuracy and molding stability to ensure the dimensional accuracy and surface quality of the die-casting parts.
The structural design of automotive die-casting molds is crucial for ensuring die-casting quality. A mold typically consists of a fixed die, a movable die, a core, a cavity, a runner system, a venting system, and an ejector system. Each component must be designed in concert to meet the requirements of the die-casting process. The runner system is particularly critical, as it introduces molten metal into the cavity. Its shape, size, and position directly influence the filling speed and pressure distribution of the molten metal. For large, complex die-castings, multiple gates are often used to ensure that the molten metal simultaneously fills all areas of the cavity, minimizing molding defects. The venting system must ensure that gases within the cavity can be discharged smoothly, preventing problems such as pores and cold shuts caused by trapped gas. Venting grooves are typically placed at the last fill point and corners of the cavity. Their depth and width must be precisely calculated based on the alloy type and die-casting process parameters. The ejector system must ensure smooth and damage-free ejection of the die-casting. The ejector should be located in a rigid area of the die-casting to avoid deformation during ejection.
The selection of mold materials is a crucial factor in the design of automotive die-casting molds, directly impacting mold life and molding accuracy. Due to the large production volumes of automotive die-castings, molds must withstand frequent hot and cold cycles and the wear and tear of molten metal. Therefore, mold materials must possess high strength, hardness, wear resistance, and excellent thermal fatigue resistance. Commonly used mold materials include H13 hot work die steel and 3Cr2W8V. These materials, after proper heat treatment, can withstand the high-temperature and high-pressure environments required for die-casting molds requiring high precision and surface quality. Surface treatments such as nitriding and chrome plating are also required to enhance wear and corrosion resistance, extending mold life. Cost considerations must also be taken into account when selecting mold materials. While meeting application requirements, cost-effective materials should be selected to reduce mold manufacturing costs.
The precision design of automotive die-casting molds directly impacts the dimensional accuracy and assembly performance of the die-cast parts. The mold’s machining accuracy must exceed the precision requirements of the die-cast parts. Typically, the mold’s dimensional tolerance is controlled within 1/3 to 1/2 of the die-cast part’s tolerance. During the design process, the shrinkage of the molten metal must be fully considered. The mold’s dimensional magnification factor should be appropriately determined based on the alloy material and the casting structure to ensure that the die-cast part meets the required design dimensions after cooling. The mold’s guide mechanism is also crucial. It ensures precise alignment of the fixed and movable molds during the closing process, preventing misalignment that can affect the die-cast part’s accuracy and mold life. The guide mechanism typically utilizes a combination of guide pins and guide sleeves, with the clearance between the guide pins and sleeves strictly controlled to ensure accurate guidance. Furthermore, the mold’s parting surface must be smooth and flat to avoid defects such as flash and burrs in the die-cast part caused by uneven parting surfaces, which can affect the die-cast part’s appearance and assembly performance.
With the continuous development of the automotive industry, the demand for lightweight, integrated, and high-performance automotive die-casting parts is increasing, driving continuous innovation in automotive die-casting mold design technology. In recent years, technologies such as computer-aided design (CAD) and computer-aided engineering (CAE) have been widely used in mold design. Through 3D modeling and numerical simulation, the die-casting process can be simulated and analyzed before mold manufacturing. This allows prediction of the molten metal filling process, temperature field distribution, and stress distribution, allowing timely identification of mold design issues and optimization, thereby improving mold design reliability and efficiency. At the same time, modular design concepts are also gradually being applied to automotive die-casting mold design. By standardizing and modularizing common mold components, this not only shortens mold design and manufacturing cycles, but also improves mold interchangeability and versatility, reducing production costs. Furthermore, the application of 3D printing technology in mold manufacturing enables the processing of complex cavities and conformal cooling channels, further improving mold cooling efficiency and molding quality, and providing strong support for the high-quality production of automotive die-casting parts.
