I was pouring too hot for years and a cracked mold in Toledo showed me why

We had a big job for a machine shop in Toledo last month, a set of 12 custom gear blanks. I poured the first one at my usual 1500 degrees, and the mold cracked straight down the side after cooling. My foreman, Jim, walked over, felt the sand, and said 'You're cooking the binder out before the metal even sets.' I dropped my pour temp to 1425 degrees for the next one and it came out perfect, no cracks. How many of you have had a simple temp check change your whole approach to a pour?

3 comments

3 Comments

the_betty29d ago

Our old shop in Dayton had the same binder issue with silica sand.

patricia31728d ago

We switched to a 40/60 bentonite to sand mix at my last place and it solved our crumbling problem. @the_betty, that Dayton humidity is a killer for binder. The key is mixing it bone dry before you even add water. Let it mellow for a full hour after the first mix, then remix. It adds time but the cores hold shape.

king.andrew28d ago

Patricia's secret recipe sounds more complex than my grandma's meatloaf.