Old hand told me to always check the sand first

I was working a big pour at a shop in Pittsburgh about 2 years ago. The guy running the line, been there since the 80s, walked over and pointed at the moisture meter on the bench. He said "You never check that before you mix, you're gonna get cold shuts every time." I didn't think much of it until that batch came out with three bad castings. Cost us $400 in scrap and an hour of rework. Has anyone else had an old timer save them from a simple mistake like that?

3 comments

3 Comments

the_john4d ago

Man I've read that moisture is the number one killer in sand casting. There was this old article from a foundry magazine back in 2015 that said even 2% extra moisture can mess up your permeability and cause gas defects. Your sand guy knew what he was talking about. Those cold shuts are a nightmare to grind out after the fact. Bet you never skip that meter again.

aliceharris4d ago

Had a batch last summer where the moisture meter was reading 3.8% and I figured it was close enough. Spent the next two days chasing porosity in every pour and cracking open castings that looked fine on the outside but were spongy inside. Now I check the sand before every shift and keep a log of the readings. You think 2% is bad, try running at 4% and watch your scrap rate double. Do you use a microwave tester or the calcium carbide method for checking?

beng514d ago

@the_john that 2015 article probably saved a lot of guys from headaches, but the bigger issue nobody mentions is how the binder system reacts when moisture spikes. I ran silica sand with a phenolic urethane binder and at 3% moisture the catalyst basically quit working. Ended up with half cured cores that crumbled during pouring. Real nasty mess that is impossible to predict from a meter alone.