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We cut our scrap rate by almost half after switching to a different riser sleeve design
For about six months, our pour floor was seeing a 12% scrap rate on a specific gray iron gear housing... mostly from shrinkage defects near the top. Our lead pattern maker suggested trying a bigger exothermic riser sleeve instead of the standard insulating ones we'd always used. We switched over on three patterns as a test run. After 200 castings tracked over three weeks, the scrap on those parts dropped to just under 7%. The extra heat from the exothermic sleeve kept the metal liquid longer up top, so it fed the shrinkage better. Has anyone else had good results with a specific brand or size of exothermic sleeve for heavier sections?
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holly_gonzalez611mo ago
My buddy at the old shop had a similar fight with some steel valve bodies. They were stuck at a high scrap rate for months, blaming everything but the risers. Finally, their foundry manager ordered a pallet of some off-brand exothermic sleeves as a last-ditch effort. The change was stupidly fast. They went from sorting out bad castings every shift to maybe finding one or two a week. It was the same idea, the extra heat kept everything feeding right. He never shut up about it.
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river_hart181mo ago
That story from your buddy is spot on, @holly_gonzalez61. Read a case study a while back about a place making heavy steel parts. They had the same exact problem, shrinkage all over the place. Their engineers were looking at everything except the feeder system. Switched to exothermic sleeves and their yield shot up almost overnight. It's crazy how often the fix is just keeping that heat in the right spot longer. Makes you wonder how much scrap is out there from simple feeding problems.
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