Preventing Cracks in Aluminum Alloy Die Castings
Features and inspection methods: The surface of the casting has linear or irregular narrow and uneven patterns, which have a development trend under external forces. Cold cracking - the metal at the cracking point has not been oxidized. Hot cracking - the metal at the crack is oxidized.
Cause of occurrence:
1. The iron content in the alloy is too high or the silicon content is too low.
2. The excessive content of harmful impurities in the alloy reduces its plasticity.
3. Aluminum silicon alloy: Aluminum silicon copper alloy contains zinc or has a high copper content; Aluminum magnesium alloy contains too much magnesium.
4. The mold temperature is too low.
5. There are significant changes in the wall thickness of castings, which hinder shrinkage.
6. Excessive mold retention time and high stress.
7. Uneven force distribution during ejection.
Preventive measures:
1. Properly controlling the alloy composition, in some cases pure aluminum ingots can be added to the alloy to reduce the magnesium content in the alloy; Alternatively, aluminum silicon intermediate alloy can be added to the alloy to increase the silicon content.
2. Change the casting structure, increase the rounded corners, increase the demolding angle, and reduce the wall thickness difference,
3. Change or increase the ejection position to ensure even force distribution.
4. Shorten the time for mold opening or core pulling.
5. Raise the mold temperature (mold working temperature 180 ° -280 °).
Product Categories : Aluminum Die Casting
