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I tried a different riser sleeve on a big steel casting and it totally failed
We had a 500 pound gear blank pour in Tacoma last week and I swapped our usual fiber sleeve for a cheaper ceramic one to save about forty bucks. The riser froze up way too fast and we ended up with a massive shrink cavity right in the hub. Has anyone else had this happen with ceramic sleeves on heavier sections?
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ellis.charles2mo ago
Man that's a brutal lesson on forty bucks. Seen similar things happen when the insulation just isn't right for the mass.
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claire_ramirez221d ago
Did you ever read that old foundry handbook article about how ceramic sleeves actually have lower thermal conductivity than fiber once you get past a certain wall thickness? @jesse84 is right that it's a mass and heat capacity problem, I remember someone from a shop up in Portland posting about the same issue with gear blanks. The math just doesn't work out for heavy sections unless you're pouring super hot.
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