Unpopular opinion: Cold risers aren't always needed for small aluminum parts

I work with A356 aluminum and kept getting voids in thin wall castings. I stopped using cold risers on small parts and focused on pour control. By keeping the ladle steady and pouring slow, the quality improved. Anyone have tips for gating designs to help with this?

3 comments

3 Comments

caseys521mo ago

Pour slow is the whole game. Your gating needs to be dead simple to match. A single wide gate at the bottom works best. It keeps the metal from splashing around. That splash is what traps air and makes voids. A taller sprue helps push the metal in without needing extra risers. Just let the metal fill the mold nice and quiet.

the_beth1mo ago

Hey, your focus on pour control is key, I saw the same thing with small A356 parts. Ditching cold risers and just pouring slow from a steady ladle fixed most of my void issues. For gating, try using a single, wider gate instead of multiple small ones to keep the flow calm. Positioning the gate at the bottom of the mold helped me avoid turbulence in thin walls. A taller sprue also gave that extra pressure to push metal into all the corners before it cooled.

anna_roberts81mo ago

Honestly, @the_beth is onto something with that taller sprue idea. I heard from an old timer that extra pressure makes a huge difference. Tbh, keeping the flow calm seems to be the real trick here.