Design requirements for die castings

Update:13 Nov 2020

(1) Requirements for the shape and structure of die-casting parts: a. Eliminate internal undercuts; b. Avoid or reduce core-pulling parts; c. Avoid crossover of cores; a reasonable structure of die-casting parts can not only simplify the structure of die-casting molds, and reduce manufacturing costs, It also improves the quality of castings,

(2) Wall thickness requirements for casting design: The wall thickness of die castings (usually called wall thickness) is a factor of special significance in the die casting process, and the wall thickness is closely related to the entire process specification, such as the calculation of filling time, internal gate Selection of speed, calculation of solidification time, analysis of mold temperature gradient, the effect of pressure (final specific pressure), the length of mold retention time, the level of casting ejection temperature and operating efficiency; a. Thicker parts will cause die casting The mechanical properties of the parts are significantly reduced, and the compactness of thin-walled castings is good, and the strength and pressure resistance of the castings are relatively improved; b. The wall thickness of the castings should not be too thin. Too thin will cause poor filling of the aluminum liquid and difficulty in forming, making the aluminum alloy cannot be welded. Good, the surface of the casting is prone to defects such as cold barriers, and brings difficulties to the die casting process; as the wall thickness increases, the internal pores, shrinkage and other defects 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 thickness of the section should be kept uniform. In order to avoid defects such as shrinkage, the thickness of the thick wall of the casting should be reduced (material reduction), and ribs should be increased; for large-area flat thick-walled castings, set Ribs to reduce the wall thickness of the casting; according to the surface area of the die casting, the reasonable wall thickness of the aluminum alloy die casting is as follows: die casting surface area/mm2 wall thickness S/mm≤251.0~3.0>25~1001.5~4.5>100~4002.5~5.0> 4003.5~6.0

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(3) Requirements for casting design ribs:

The function of the rib is to increase the strength and rigidity of the parts after the wall thickness is thinned, to prevent the shrinkage and deformation of the casting, and to avoid the deformation of the workpiece when it is ejected from the mold. It is used to act as an auxiliary circuit (metal flow path) during filling. , The thickness of the die-casting ribs should be less than the thickness of the wall where it is located, generally 2/3~3/4 of the thickness at that location;

(4) Fillet requirements for casting design:

All wall-to-wall connections on die-casting parts, regardless of right angles, acute angles or obtuse angles, blind holes and groove roots, should be designed with rounded corners. Only when the parting surface is expected to be determined, the rounded connection should not be used. , The remaining parts must generally be rounded corners. The rounded corners should not be too large or too small. Die castings that are too small are prone to cracks, and too large are prone to loose shrinkage holes. The fillets of die castings generally take: 1/2 wall thickness ≤ R ≤ wall Thick; the role of rounded corners is to help the flow of metal, reduce eddy or turbulence; to avoid the presence of rounded corners and cause stress concentration and cracking; when the parts are to be electroplated or coated, rounded corners can be obtained Uniform coating to prevent deposition at sharp corners; can prolong the service life of the die-casting mold and prevent corner chipping or cracking due to the sharp corners of the mold cavity;

(5) Casting slope requirements for die casting design:

The role of the slope is to reduce the friction between the casting and the mold cavity, and it is easy to take out the casting; to ensure that the surface of the casting is not strained; to extend the service life of the die-casting mold, the general minimum casting slope of aluminum alloy die casting is as follows: the smallest casting slope of aluminum alloy die casting Core hole on outer surface and inner surface (single side) 1°1°30′2°

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