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Old timer at the furnace told me to stop over-packing my sprue cup | Foundry Workers - nhfree.com

Old timer at the furnace told me to stop over-packing my sprue cup

He said I was trapping air and causing porosity in my castings. I ignored him for months until I finally tried it his way on a run of 12 stainless steel parts in Columbus. Every single one passed x-ray where I'd usually lose 3 or 4. Anyone else have a senior hand give you advice that felt wrong but saved your hide?

3 comments

3 Comments

andrew8545mo ago

Ignore that guy. Overpacking the sprue cup forces metal through the gate fast and gives you better fill before any freezing starts. Ive seen guys go from a full cup to barely half and get cold shuts that looked like cracks on the xray. If your current way loses 3-4 out of 12, you got process issues somewhere else not the cup.

kelly.daniel5mo ago

andrew854 is out here dropping truth bombs like it's hot. Maybe it's just me but I've seen guys overthink the sprue cup so hard they start blaming the pourer, the alloy, the weather, everything except their own process. If you're losing 3 or 4 out of 12, idk, that's like a 25-33% scrap rate, which is basically a hobbyist's nightmare not a production floor reality. Sounds like you got porosity hiding somewhere or your gate design is crying for help. Honestly, if someone told me to half-fill my cup, I'd laugh and ask when they last ran a job without chasing cold shuts all day. But hey, what do I know, I'm just the guy who fills the cup and doesn't look back.

kais673mo ago

I read a metallurgy blog last week that said sprue cup height directly affects the pressure curve during fill... really changes how the metal behaves in the cavity. @andrew854 is right that overpacking keeps that pressure up and stops premature freezing from causing defects like cold shuts or incomplete sections. If your scrap rate is that high, it makes more sense to look at your gating ratio or venting instead of blaming the cup.