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Core Summary: How to design die cast parts? First, the design of die casting involves four aspects: a, that is, the requirements of pressure casting on the shape and structure of parts; B. Process performance of die casting parts; C. Dimensional accuracy and surface requirements of die casting parts; d. Determination of parting surface of die casting parts; The design of die casting parts is an important part of die casting production technology, the design must consider the following problems: the choice of mold parting surface, the opening of the gate, the selection of the top rod position, the shrinkage of the casting, the dimensional accuracy of the casting, the prevention of the internal defects of the casting, the related requirements of the casting hole, the related requirements of shrinkage deformation and the size of the processing allowance.
How are die cast parts designed?
 
 
1. The design of die casting involves four aspects:
 
 
A. The requirement of pressure casting on the shape structure of parts; B. Process performance of die casting parts; C. Dimensional accuracy and surface requirements of die casting parts; d. Determination of parting surface of die casting parts; The design of die casting parts is an important part of die casting production technology, the design must consider the following problems: the choice of mold parting surface, the opening of the gate, the selection of the top rod position, the shrinkage of the casting, the dimensional accuracy of the casting, the prevention of the internal defects of the casting, the related requirements of the casting hole, the related requirements of shrinkage deformation and the size of the processing allowance.
 
 
Two, the design principle of die casting is:
 
 
a, the correct selection of die casting materials;
 
 
b. Reasonably determine the dimensional accuracy of die casting parts;
 
 
c, try to make the wall thickness distribution uniform;
 
 
d. Add craft park corners at each corner to avoid sharp corners.
 
 
Three, the classification of die casting:
 
 
According to the use requirements can be divided into two categories, a large load bearing parts or have a higher relative speed of the parts, check the item size, surface quality, chemical composition, mechanical properties (tensile strength, elongation, hardness);
 
 
The other type is for other parts, check items such as size, surface quality and chemical composition.
 
 
In the design of die casting, it should also pay attention to the parts should meet the technical requirements of die casting. The technology of die casting is considered from the position of parting surface, the position of pushing rod on top surface, the related requirements of casting hole, the related requirements of shrinkage deformation and the size of processing allowance. The rational determination of parting surface of die casting surface can not only simplify the structure of die casting, but also ensure the quality of casting.
 
 
Four, die casting design requirements:
 
 
(I) The shape and structure requirements of die casting: a. Eliminate the internal side concave; b. Avoid or reduce the core pulling part; c. Avoid core crossing; Reasonable die casting structure can not only simplify the structure of die casting, reduce the manufacturing cost, but also improve the casting quality.
 
 
(II) Wall thickness requirements for casting design: The wall thickness of die casting (usually called wall thickness) is a factor of special significance in die casting process. The wall thickness is closely related to the whole process specification, such as the calculation of filling time, the selection of the inner gate speed, the calculation of solidification time, the analysis of mold temperature gradient, the effect of pressure (the final specific pressure), the length of mold retention time, the level of casting ejection temperature and the operation efficiency. a. The thickness of the wall of the parts will significantly decrease the mechanical properties of the die castings, and the density of the thin-wall castings is good, which relatively improves the strength and pressure resistance of the castings; b. Casting wall thickness should not be too thin. Too thin will cause poor filling of liquid aluminum, molding difficulties, poor melting of aluminum alloy, easy to produce cold insulation defects on the casting surface, and bring difficulties to the die casting process; As the wall thickness of die casting increases, the internal defects such as pores and shrinkage holes increase. Therefore, on the premise of ensuring sufficient strength and stiffness of the casting, the wall thickness of the casting should be reduced as far as possible and the thickness of the section should be uniform. In order to avoid the defects such as shrinkage and loosening, the thickness (material reduction) of the thick wall of the casting should be reduced and the reinforcement should be increased. For large-area slab thick-wall castings, reinforcement is provided to reduce the wall thickness of the castings. According to the surface area of the die casting, the appropriate wall thickness of aluminum alloy die casting is as follows: Surface area /mm2 wall thickness S/mm ≤25 1.0 ~ 3.0 > 25~100 1.5 ~ 4.5 > 100~400 2.5 ~ 5.0 > 400 3.5 ~ 6.0.
 
 
(3) Requirements for casting design bars:
 
 
The role of reinforcement is to improve the strength and rigidity of parts after the wall thickness is thinned, to prevent the shrinkage and deformation of castings, and to avoid the deformation of the workpiece when it is driven out of the mold. When filling, the thickness of the die casting reinforcement should be less than the thickness of the wall, which is generally taken as 2/3~3/4 of the thickness.
 
 
(IV) Requirements for rounded corners of casting design:
 
 
Die casting wall to wall connection, no matter the right Angle, acute Angle or obtuse Angle, blind hole and groove root, should be designed into rounded corners, only when it is expected to determine the part of the parting surface, do not use rounded corners, the rest of the general must be rounded corners, rounded corners should not be too large or small, too small die casting is easy to crack, too large easy to produce loose shrinkage holes, die casting rounded corners are generally taken: 1/2 wall thickness ≤R≤ wall thickness; The purpose of rounded corners is to aid the flow of metal and reduce eddies or turbulence; Avoid cracking caused by stress concentration due to the existence of rounded corners on the parts; When parts are to be electroplated or coated, rounded corners can obtain uniform coating to prevent the deposit of sharp corners; It can prolong the service life of die casting die and avoid the collapse or cracking caused by the existence of sharp Angle of die cavity.
 
 
(v) Casting inclination requirements for die casting design:
 
 
The Angle effect is to reduce the friction between the casting and the mold cavity, easy to remove the casting; Ensure that the casting surface is not strained; To extend the service life of die casting die casting, the general minimum casting inclination of aluminum alloy die casting is as follows: The minimum casting inclination of aluminum alloy die casting outer surface inner surface core hole (unilateral)1° 1°30 '2°.