Had a close call with a green sand mold that taught me a quick lesson

I was ramming up a big flask for a gear housing pour last Thursday, the kind we run maybe twice a year. I was rushing to beat the shift change, and I didn't notice I'd left a corner of the mold a bit soft. When we went to pour, the iron hit that weak spot and started to weep, just a slow creep out the side of the cope. My lead, Frank, saw it first and yelled 'stop the pour' before it could get worse. We let it cool, broke the mold, and sure enough, the casting had a massive fin we had to grind off. It cost us an extra hour and about 40 pounds of iron. I've been in this shop for eight years, and that was a dumb, avoidable mistake. What's your go-to check for mold hardness when you're working on a complex job like that?

3 comments

3 Comments

drew5517d ago

Frank's quick call saved a lot worse. I always do a quick drag test with a small nail in the corners before closing up.

tara79317d ago

Honestly, that nail test @drew55 mentioned can give a false sense of safety on a deep job. My go-to is just using the old thumb knuckle press in a few spots, since you can feel the difference between a firm surface and a truly packed corner. It's saved me from a few weepers over rushing.

river_allen16d ago

Tara's thumb knuckle method sounds like a great way to also check if you're still strong enough to open a pickle jar later.