Design of die casting mold for housing and base
The housing and base serve as the fundamental load-bearing components of various types of mechanical equipment. The quality of their die-castings directly impacts the overall performance and stability of the equipment. Therefore, the design of die-casting molds for these components must balance structural strength, molding accuracy, and production efficiency. These die-castings are typically large, complex, and have uneven wall thicknesses. They may contain internal details such as ribs, bosses, and hole systems, while the exterior must be precisely assembled with other components. During the initial design phase, a comprehensive analysis of the housing and base’s stress response, operating environment, and assembly requirements is required. For example, a machine tool base must withstand the vibrations and loads of the equipment during operation, so the mold design must ensure sufficient rigidity for the die-casting. For electrical housings, heat dissipation and sealing must be considered, so the mold must ensure cavity integrity and surface accuracy. Furthermore, the properties of the die-casting alloy, such as fluidity and shrinkage, must be considered to develop a reasonable mold design, laying the foundation for subsequent structural design.
The structural design of die-casting molds for housings and machine bases must prioritize the molding and demolding of complex cavities. Since these die-cast parts are often box-shaped or cylindrical, molds typically utilize horizontal or vertical parting. For parts with deep cavities or complex internal structures, a combined core and cavity may be necessary. The core design must ensure sufficient strength and rigidity to withstand the high pressures of the die-casting process. Slender or cantilevered cores, in particular, require additional support structures to prevent deformation or breakage. The runner system should ensure uniform filling of the entire cavity by the molten metal. Large housing and machine base die-castings often utilize multi-point or ring gates to allow simultaneous filling from multiple directions, minimizing filling time and pressure loss. The venting system should be designed to cover every corner of the cavity, especially at rib intersections and at the base of bosses, where gas is likely to accumulate. Sufficient venting slots should be provided, and their dimensions should be precisely calculated based on the alloy type to ensure smooth venting while preventing overflow and flash.
The mold material selection must meet the requirements of high-volume production and high-quality molding for the die-cast housing and base. Due to the large size of the die-cast housing and base, the mold template and cavity module must possess high strength and rigidity to prevent deformation during mold closing and die-casting. H13 hot-work die steel is commonly used. After quenching and tempering, this material can reach a hardness of 40-45 HRC. It has excellent thermal fatigue and wear resistance and can withstand repeated hot and cold cycles and molten metal erosion. For high-precision housing molds, the cavity surface can be nitrided to form a hardened layer with a hardness of up to 800-1000 HV, improving the mold’s wear and corrosion resistance and extending its service life. Furthermore, the mold’s guide components and ejection mechanism must be made of high-strength alloy steel, such as quenched and tempered 45 steel, to ensure stable precision over long-term use.
The die-casting components of the housing and base require high dimensional accuracy and form and position tolerances, necessitating strict control of mold precision design. The mold cavity and core dimensions must be precisely calculated based on the shrinkage of the die-casting. Different die-casting alloys have varying shrinkage rates; for example, aluminum alloys typically shrink between 0.8% and 1.2%. This factor must be taken into account during mold design to ensure that the die-casting meets design requirements after cooling. For key areas such as assembly holes and locating surfaces on the housing and base, high-precision machining, such as grinding and electro-spark machining, is required to maintain dimensional tolerances within IT7-IT8 standards. The mold’s guide mechanism utilizes precision guide pins and bushings, with clearances controlled to 0.01-0.02mm. This ensures accurate alignment during mold closing and prevents flash or dimensional deviations in the die-casting due to misalignment. The flatness of the parting surface must be controlled within 0.01mm/100mm, and the sealing grooves on the parting surface must be designed to ensure a good seal to prevent molten metal leakage during the die-casting process.
With the increasing demand for large, precision die-cast housings and machine bases in the manufacturing industry, mold design technology is constantly innovating. Computer-aided design and engineering (CAD/CAE) technology has become a crucial tool for mold design. Three-dimensional modeling allows for intuitive visualization of complex mold structures. Simulating the die-casting process using CAE software can predict the filling trajectory, temperature distribution, and stress changes of the molten metal, enabling timely identification and optimization of mold design flaws. For example, simulation can optimize gate location to avoid eddies and air entrainment during the filling process. By analyzing the efficiency of the cooling system, conformal cooling channels can be designed to achieve uniform temperature distribution in the mold cavity, reducing internal stress and deformation in the die-casting. Furthermore, modular design concepts are being applied to large molds, standardizing common mold components such as ejector mechanisms and guides. This not only shortens mold design and manufacturing cycles but also improves interchangeability and ease of maintenance. 3D printing technology offers a new approach to manufacturing complex cores and cavities, enabling the rapid creation of complex structures difficult to achieve with traditional machining. This improves mold design freedom and manufacturing precision, providing strong support for the high-quality production of die-cast housings and machine bases.
