Update: Tried a different sand mix for a core and it came out way too hard

We had a rush job for some small gear housings last week and ran low on our usual binder. I mixed in about 20% of this new sodium silicate stuff the supplier gave us as a sample. The cores set up rock solid, almost like concrete, and were a nightmare to shake out after the pour. Cleanup took twice as long and we had to be really careful not to damage the casting. Anyone else had a bad time with silicate binders, or know a good fix for this?

4 comments

4 Comments

river9523mo ago

Oh man, that sounds rough. I used to think harder cores were always better, until we had a batch that just would not break down. We ended up with a few scrap castings because the shakeout cracked them. Now I'm super careful with any new binder mix, always test a tiny core first. That silicate stuff seems like overkill for most jobs.

oliver_nguyen153mo ago

Ever try to drill out a core that just won't quit? We had a big valve body where the core was basically glass, took us forever to chip it out with air hammers. That silicate binder is no joke, it makes stuff way too permanent. Sometimes the old school oil sand mix is just better because it knows when to give up.

leehall3mo ago

Silicate cores are the worst, they turn into concrete. Seen guys wreck good castings trying to get that stuff out.

gray_morgan1mo ago

Honestly, nothing like spending half your shift playing archaeologist chiseling out a core that decided to become a permanent fixture. That sodium silicate sample sounds like it was designed by someone who hates cleanup. Ngl, I'd rather deal with a soft core that crumbles than risk cracking a good casting trying to excavate that rock-hard mess.