How to design die casting parts?

[China Aluminum Network] how to design die-casting parts?
First, the design of die castings involves four aspects:
a, that is, the requirements of the shape and structure of the parts for pressure casting; b. The technological performance of the die castings; c. The dimensional accuracy and surface requirements of the die castings; d. The determination of the parting surface of the die castings; the part design of the die castings is a die casting production technique. In the important part of the design, the following issues must be considered when designing: the choice of mold parting surface, the opening of the gate, the selection of the position of the ejector pin, the shrinkage of the casting, the dimensional accuracy of the casting, the prevention of the internal defects of the casting, and the related holes Requirements, shrinkage deformation requirements, and the size of the machining allowance;
Second, the design principles of die castings are:
a. Correctly select the material of the die casting, b. Determine the dimensional accuracy of the die casting reasonably; c. Try to make the wall thickness evenly distributed; d. Increase the craft corner at each corner to avoid sharp corners.
Third, the classification of die castings:
According to the use requirements can be divided into two categories, one type of parts subject to higher loads or parts with a higher relative speed of movement, the inspection items are size, surface quality, chemical composition, mechanical properties (tensile strength, elongation , Hardness); the other is other parts, the inspection items are size, surface quality and chemical composition. In the design of die castings, it should also be noted that the parts should meet the process requirements of die casting. The technical properties of die casting take into consideration the position of the parting surface, the position of the top surface push rod, the relevant requirements for the casting hole, the relevant requirements for shrinkage deformation, and the size of the machining allowance. Reasonable determination of the die casting surface of the parting surface not only simplifies the die-casting structure but also ensures the quality of the casting. Die casting parts design requirements.
Fourth, the design requirements of die castings:
(1) Shape and structure requirements of die castings: a. Elimination of internal undercuts; b. Avoidance or reduction of core-pulling parts; c. Avoidance of core-crossings; Reasonable die-cast structure not only simplifies die-casting structure, but also reduces manufacturing costs. At the same time improve the quality of castings,
(B) the wall thickness of the casting design requirements: die casting wall thickness (usually known as the wall thickness) is a special significance factor in the die casting process, the wall thickness and the entire process specification is closely related, such as the filling time calculation, in the gate Selection of speed, calculation of solidification time, analysis of mold temperature gradient, effect of pressure (compared with end-to-end pressure), length of mold-remaining time, level of ejected temperature of casting and operating efficiency; a. Thickness of wall thickness of part The mechanical properties of die castings are obviously reduced, and the thin-walled castings have good compactness and relatively increase the strength and pressure resistance of the castings. b. The wall thickness of the castings can not be too thin, and the thinness of the castings can cause poor filling of the aluminum liquid, causing difficulties in molding and welding the aluminum alloy. Bad, easy to produce cold septum and other defects on the casting surface, and to the die casting process; die castings with the increase in wall thickness, its internal porosity, shrinkage and other defects increase, so to ensure that the casting has sufficient strength and stiffness under the premise of The thickness of the casting should be minimized and the thickness of the section should be kept uniform. To avoid defects such as shrinkage and shrinkage, the thickness of the casting should be reduced (reduced) and the ribs should be increased; for large areas Plate thick-walled castings, set ribs to reduce the wall thickness of the castings; according to the surface area of the die-castings, the reasonable wall thickness of the aluminum alloy die-castings is as follows: Die-casting surface area/mm2 Wall thickness S/mm ≤ 251.0 to 3.0> 25~1001.5 to 4.5 >100~4002.5~5.0>4003.5~6.0
(3) Requirements for casting design ribs:
The function of the ribs is to increase the strength and rigidity of the parts after thinning the wall thickness, to prevent shrinkage deformation of the castings, to avoid deformation when the workpiece is ejected from the mold, and to act as auxiliary loops (paths for metal flow) during filling. The thickness of the die casting ribs should be less than the thickness of the wall, generally 2/3~3/4 of the thickness of the part;
(four) casting design fillet requirements:
The connection between the wall and the wall of the die casting shall be rounded except for right angles, acute or obtuse angles, blind holes and the roots of the grooves. Only when the part to be determined as the parting surface is specified, the fillet connection is not used. The rest of the parts must be rounded, rounded corners should not be too large or too small, too small die castings are easy to produce cracks, too large and easy to produce loose shrinkage hole, die casting fillet is generally taken: 1/2 wall thickness ≤ R ≤ wall Thick; the role of the rounded corners is to help the flow of metal, reduce eddy currents or turbulence; to avoid cracking due to stress concentration on the part due to the presence of the fillet; when the part is to be plated or coated, the fillet can be obtained Uniform plating to prevent deposits at sharp corners. Can extend the service life of die-casting molds without causing chipping or cracking due to the sharp corners of the mold cavity;
(5) Casting slope design requirements for die castings:
The role of slope is to reduce the friction between the casting and the mold cavity, easy to remove the casting; to ensure that the casting surface does not pull; to extend the life of the die casting mold, aluminum alloy die castings generally smaller casting slope is as follows: aluminum alloy die casting smaller casting The outer surface of the slope surface core hole (unilateral) 1 ° 1 ° 30'2 °.