Spent 2 years pouring molds with the wrong sand mix

I was over at Jones Metal in Tulsa last week watching some old timer set up his floor work and noticed he was using way less water in his green sand than I ever did. He asked what my moisture level was and when I told him around 4% he just shook his head and showed me his 2.5% mix that held together way better. Has anyone else had that moment where you realized you had been doing a basic step wrong for years?

3 comments

3 Comments

logan_ellis27d ago

Huh, I gotta say that 2.5% sounds really dry to me but I've been wrong before. I've been running my green sand at around 3.5-4% for the last 8 years and never had compaction issues on the flasks we pour at our shop. A guy I trust at a job shop in Ohio runs his at 3.8% and gets perfect pulls every time on their No. 2 cope. Maybe its a regional thing with the sand base or the clay you're using because I tried dropping down to 3% once and got nothing but crumbly edges on my deep pockets. Your mileage will definitely vary depending on what you're casting and how hot you're running.

mila_campbell2527d ago

You're spot on with that @logan_ellis, 2.5% would have me sweating bullets too. I ran my system at 3.6% for years and anything below 3.2% gave me nothing but trouble on my deeper pockets, especially on thicker sections. Had a job last fall where I tried bumping it down to 2.8% thinking it would cut down on gas defects, and ended up with pulls that looked like they'd been through a cheese grater. The clay type really does make a difference too, I switched from western to southern bentonite and had to tweak my moisture up almost half a point to get back to that sweet spot. What kind of clay are you running with at 3.5-4%?

the_tessa27d ago

I once saw a guy try 2.2% and his mold collapsed mid-pour.