Switched from silica sand to olivine sand for my green sand molds, way better finish

Been running a small job shop for about 6 years now. Used silica sand forever because that's what my old man used. Last month I had a job for some thin wall castings in ductile iron and kept getting burn on problems. Switched to olivine sand on a whim and the surface finish is night and day. Less thermal expansion so less scabbing too. Only downside is it costs more per ton but I'm using less binder now so it might even out. Anyone else try different sand types for specific alloys?

2 comments

2 Comments

mason72814h ago

Olivine might give a better finish but silica's thermal shock resistance is still hard to beat for larger iron pours.

xena_kim13h agoMost Upvoted

Thermal shock resistance is still hard to beat" - yeah, but here's something people skip over. Silica dust is the real killer. Inhaling that stuff from mixing or cleanup is no joke, and a lot of guys act like it doesn't matter for a few pours. Olivine might cost more and need more care, but it's way less harmful if you're doing this regularly. I'd rather deal with a slightly rougher finish than risk lung problems down the line. Plus, for big iron pours, you can always preheat your mold to compensate for silica's lack of thermal shock. It's an extra step, but it works.