The rationality of die casting design is related to the entire die casting molding process, in the design of die casting, should fully consider the structural characteristics of die casting, die casting process requirements, minimize the design of die casting in the die casting process defects, with the best design scheme to maximize the quality of die casting.

1. Reasonably design the wall thickness of die castings

Aluminum alloy die casting structure design should fully consider the wall thickness problem, wall thickness is a special factor in the die casting process, wall thickness and the entire process specification has a close relationship, such as the calculation of filling time, the selection of inner gate speed, the calculation of solidification time, the analysis of mold temperature gradient, the role of pressure (final specific pressure), the length of mold retention time, the level of casting ejection temperature and operation efficiency; If the design wall thickness is too thick, external surface defects such as shrinkage holes, trachoma, pores, and coarse internal grains will occur, which will reduce mechanical properties and increase the quality of parts, resulting in rising costs; The design wall thickness is too thin, which will cause poor filling of molten aluminum, difficult forming, poor dissolution of aluminum alloy, easy to have defects such as difficult surface filling and lack of materials on the surface of castings, and bring difficulties to the die-casting process; With the increase of pores, the internal pores, shrinkage holes and other defects of the die casting increase, so 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 uniform.

2. Reasonable design of die casting stiffeners

For large plane or thin wall die castings, its strength, rigidity, easy to deform, then the use of stiffeners can effectively prevent die casting shrinkage, fracture, eliminate deformation, enhance the strength and rigidity of die castings, for too high columns, tables and other structures, you can use stiffeners to improve stress distribution, prevent root fracture, while stiffeners can assist the flow of molten metal, improve the filling performance of castings. The root thickness of the stiffener is not greater than the thickness of the wall, and the general thickness is designed to be 0.8~2.0mm; the release slope of the stiffener is generally designed to be 1°~3°, and the higher the height, the smaller the design demolding slope; Rounded corners should be added to the root of the stiffener to avoid sharp changes in the section of the part, and at the same time assist the flow of molten metal, reduce the stress concentration of the part, and improve the strength of the part, and the fillet is generally close to the wall thickness here; The height of the stiffener is generally not more than 5 times its thickness, the thickness of the stiffener is generally required to be uniform, if the design is too thin, the stiffener itself is easy to break, if it is too thick, it is easy to produce dents, pores and other defects.

3. Reasonably design the mold slope of die castings

The function of the die casting mold slope is to reduce the friction between the casting and the mold cavity, and it is easy to take out the casting; Ensure that the die-casting surface is not strained, and at the same time can extend the mold life. The mold output slope is related to the height of the die casting, and the larger the height, the smaller the mold output slope. Under normal circumstances, the mold exit slope of the outer surface of the die casting is about 1/2 of the mold exit slope of the inner cavity, but in the actual design, the mold exit slope of the inner and outer surfaces of the die casting can be designed to be consistent to maintain uniform wall thickness and simplify the structural design.

4. Reasonable design of processing allowance

Machining should be avoided as much as possible when designing die-casting parts, which will damage the dense layer on the surface of the part and affect the mechanical properties of the part; It will expose the pores inside the die casting, affect the surface quality, and also increase the cost of parts. When the die casting cannot avoid machining, the design with a large amount of cutting should be avoided as much as possible, and the structural design should be as convenient as possible for machining or reduce the machining area to reduce the cost of machining.

The dimensional accuracy requirements of the upper part of the die casting parts are high, or some plane surface roughness requirements are high, the die casting process is difficult to meet the requirements, then subsequent processing is required, for this part of the structure, the design should try to reserve the processing allowance. The strength and hardness of the surface of the die casting are higher than the inside, and attention should be paid to retaining the density of the surface when machining, so the margin of machining can not be excessive, and too much machining is likely to produce pores, outer surface defects.

5. Aluminum alloy die casting spraying design

The surface spraying design of die-casting parts generally adopts the powder spraying process, and its principle is electrostatic powder spraying: the paint is mainly polarized through the electrode, and then the object to be sprayed has an opposite charge, and the powder is uniformly attached to the surface of the object under the action of electric field force. Characteristics of powder spraying process: powder electrostatic spraying will not cause air pollution, powder can be recycled to reduce the cost of material consumption, coating performance acid resistance, alkali resistance, corrosion resistance is good.