Aluminum castings can be manufactured as aluminum die-casting automotive parts, aluminum die-casting automotive engine fittings, aluminum die-casting engine cylinders, aluminum die-casting gasoline engine cylinder heads, aluminum die-casting valve rocker arms, aluminum die-casting valve supports, aluminum die-casting power accessories, aluminum die-casting motor end caps, aluminum die-casting housings, aluminum die-casting pump housings, aluminum die-casting building accessories, aluminum die-casting decorative accessories, aluminum die-casting guardrail accessories, aluminum die-casting aluminum wheels, and other parts. Characteristics of shrinkage defects: Shrinkage in aluminum castings generally occurs in thick areas near the sprue, at the transition between thick and thin walls, and at thin-walled areas with large flat surfaces.
When in the as cast state, the fracture surface is gray, and the light yellow color after heat treatment is grayish white, light yellow or gray black. It appears as a cloud like structure on X-ray film. Severe filamentous shrinkage can be found through X-ray, fluorescence low magnification fracture inspection methods. The causes are: 1. Poor feeding effect of the riser. 2. Too much gas content in the furnace material. 3. Overheating near the inner runner. 4. Too much moisture in the sand mold, the sand core is not dried. 5. Coarse alloy grains. 6. Improper position of the casting in the mold. 7. Too high pouring temperature and too fast pouring speed
Methods to prevent aluminum castings: 1. Pour molten metal from the riser and improve the riser design. 2. The furnace material should be clean and corrosion-resistant. 3. Set up a riser at the shrinkage area of the casting, and place a cold iron or a combination of cold iron and riser. 4. Control the moisture content of the molding sand and dry the sand core. 5. Take measures to refine the grain size. 6. Improve the position of the casting in the mold and reduce the pouring temperature and speed.