I finally fixed a persistent chill in our gray iron castings

We kept getting small, hard spots in the corners of our gear blanks, making them brittle. After two weeks of messing with the furnace temp, I tried something my grandpa mentioned from his old shop. I started pre-heating the sand molds to about 250 degrees Fahrenheit in a small oven before pouring. The next batch came out smooth, with no chill zones at all. Has anyone else tried this method for different metals?

3 comments

3 Comments

the_mia20d ago

Remember my uncle swearing by pre-heating molds for his old aluminum car parts.

holly70920d ago

My buddy Jake tried casting a new intake manifold without pre-heating his steel mold last winter. The aluminum cooled way too fast and cracked right along a weld line. He lost the whole piece and had to start over from scratch.

mark_green20d ago

Is a little chill in the corners really that big of a deal for a gear blank? Seems like a lot of extra work to heat up all that sand. I guess if you're making airplane parts or something, but for most stuff, a small hard spot might not even matter in the long run.