(1) Shape and structure requirements for die castings: A. Eliminate inner depressions; B. Avoid or reduce core pulling parts; C. Avoid core drilling; Reasonable die casting structure can not only simplify the die casting structure and reduce manufacturing costs, but also improve the quality of castings.
(2) Wall thickness requirements for casting design: The wall thickness of die castings is a factor of special significance in the die casting process. It is closely related to the entire process specifications such as the calculation of filling time, the selection of ingate speed, the calculation of solidification time, the analysis of mold temperature gradient, pressure (final specific pressure), mold residence time, casting ejection temperature and work efficiency.
a. If the wall thickness of the part is too thick, the mechanical properties of the die casting will be significantly reduced. The compactness of thin-walled castings is good, which relatively improves the strength and pressure resistance of the castings.
b. The wall thickness of the casting should not be too thin, otherwise there will be defects such as poor aluminum liquid filling, difficulty in forming, poor aluminum alloy welding, and cold insulation of the casting surface. Too thin will also bring difficulties to the die casting process. As the wall thickness increases, the internal defects such as pores and shrinkage holes of the die casting increase. Therefore, under the premise of ensuring that the casting has sufficient strength and rigidity, the wall thickness of the casting should be reduced as much as possible, and the cross-sectional thickness should be uniform. In order to avoid defects such as shrinkage, the thick wall of the casting should be thinned (cutting) and strengthened. For large-area flat thick-walled castings, in order to reduce the wall thickness of the casting, reinforcing ribs can be set; the reasonable wall thickness of aluminum alloy die castings should be calculated based on the surface area of the die casting.
(3) Requirements for reinforcement design of castings: Reinforcing ribs are used to increase the wall thickness and reduce the strength and rigidity of the parts, prevent the shrinkage and deformation of the castings, and avoid deformation when the workpiece is pushed out of the mold. It is used as an auxiliary circuit (metal flow channel) during filling. The wall thickness of die castings is generally 2/3~3/4, and the wall thickness is greater than the thickness of the reinforcing ribs.
(4) Requirements for fillet design of castings: All wall connectors on die castings, whether they are right angles, acute angles or obtuse angles, as well as the roots of blind holes and grooves, should be designed as fillets. Only when the parts expected to be separation surfaces do not use fillets, other parts should generally be filleted, and the fillets should not be too large or too small. If the size is too small, die castings are prone to cracks and loose shrinkage cavities. The fillet of die castings is generally: 1/2 wall thickness ≤ R ≤ wall thickness; helping metal flow, reducing eddy currents or turbulence, and avoiding stress concentration and cracks caused by fillets on parts are the functions of fillets; when parts need to be electroplated or coated, a uniform coating can be obtained at the fillets to prevent deposition at sharp corners; it can extend the service life of the die casting mold and will not cause angle collapse or cracking due to the sharp angles of the mold cavity.
(5) Casting inclination requirements for die casting design: The function of the incline is to reduce the friction between the casting and the cavity to facilitate the disassembly of the casting; ensure that there is no deformation on the casting surface; in order to extend the service life of the die casting mold, the minimum casting inclination angle of aluminum alloy die castings is: the minimum casting inclination angle of aluminum alloy die castings; the core hole (one side) on the outer surface and inner surface is 1130'2.