Hi,
I agree with Kipper in that if rammed properly and having adequate gates and risers the aluminum castings should not have the mentioned defects. What kind of sand are you using? I have been using Petrobond for my aluminum castings with very good results for some time. Also keep in mind that patterns should have uniform thickness on the walls to help avoid shrink cavities, and special gating and risers may be needed where there are thick sections to be cast.
Regards,
Wes |