Porosity in high wall-thickness Castings

There are two types of porosity. Shrinkage porosity is caused during solidification. Liquid aluminium has 6.6% more volume than solid aluminium. If that volume cannot be compensated for with fresh melt, you will find shrinkage porosity. The other type of porosity is entrapped air. These are air bubbles mixed within the solid aluminium. They form when the air cannot be vented or the filling is too turbulent and the air is mixed in the melt.

Porosity becomes a major issue, especially when castings have high wall thicknesses of 5 mm or more. This is particularly the case for most battery castings. They can massively profit from Rheocasting with its lamellar flow and lower shrinkage factor. In normal HPDC, casted battery housings often have leakage problems. So, these castings get scraped or impregnated to prevent leakage. Both alternatives are costly procedures.

If you want to learn more about how to avoid porosities, schedule a free consultation down below.