Three special requirements of casting method for casting structure　

   (1) Investment castings:

　　 1. Facilitate the manufacture of wax molds

2. The holes and grooves on the castings should not be too small or too deep, too small or too deep holes and grooves, which are not conducive to the smooth filling of the corresponding holes in the investment mold with the paint and sand particles during the shell making to form a suitable cavity; at the same time, Too deep holes and grooves also bring difficulties to the sand cleaning of castings. Generally, the aperture should be greater than 2mm (thin parts> 0.5mm). When the hole is through, the hole depth/aperture is less than 4-6, when the hole is not through, the hole depth/aperture is less than 2. The groove width should be greater than 2mm, and the groove depth should not exceed 2-6 times the groove width.

　　 3. Reduce hot spots and strive for uniform wall thickness. Investment casting generally does not have a separate riser, but uses a thicker sprue as the riser to directly feed the casting. To adapt to this process, a thin-walled structure should be used as much as possible, and the wall thickness distribution should conform to the principle of directional solidification.

　　4. Avoid large flat plate structure. Because the high temperature strength of the molten model shell is low, it is easy to deform, so when designing the casting structure, try to avoid large flat surfaces.

　　(2) Metal casting:

　　1. The shape and cavity of the casting should be simple, and the structural slope of the casting should be increased as much as possible, and the use of too small or deep holes should be avoided to facilitate the extraction of the core and ensure the smooth removal of the casting.

2. The wall thickness of the casting should be uniform to prevent shrinkage porosity and crack defects; at the same time, the wall thickness should not be too thin, and try to avoid large horizontal walls to prevent defects such as poor casting and cold isolation, such as aluminum-silicon alloy castings The minimum wall thickness of aluminum-magnesium alloy is 2mm~4mm, and the minimum wall thickness of aluminum-magnesium alloy is 3mm-5mm.

　　 (3) Die-casting parts:

　　 1. Die castings should try to eliminate undercuts and deep cavities.

　　 2. Try to use a thin-walled structure with uniform wall thickness. The suitable wall thickness of die castings is generally: zinc alloy 1mm-3mm, aluminum alloy 1.5mm-5mm, and copper alloy 2mm-5mm.

　　3. Inserts can be used in die-casting, and the advantages of the inserts should be fully utilized in order to produce complex parts, improve the local performance of die-casting parts and simplify the assembly process. In order to make the connection of the insert in the casting reliable, the insert should be inserted into the casting part to make grooves, bosses or knurling.