Baking Cores

Home enthusiasts discuss their Foundry & Casting work.

Moderator: Harold_V

Post Reply
jlakes85
Posts: 228
Joined: Thu Feb 23, 2012 6:07 am

Baking Cores

Post by jlakes85 »

Hi All,

I baked my first cores in the oven, but made the mistake of not using a dead flat pan/surface. I was thinking about using a pizza/baking stone to make sure everything sets right. Are there any better alternatives?

Regards,

John
RONALD
Posts: 754
Joined: Sun Oct 26, 2003 7:27 am

Re: Baking Cores

Post by RONALD »

I have never baked a core, I use the CO2 (Carbon Dioxide)- Sodium Silicate method for making cores.

It's a "Cold Box" method and requires no heat. There is no toxicity/fumes associated with this method.

I usually will mull 400 milliliters of Sodium Silicate with 25 pounds of sand. I use AFS 105, but any sand should work.

Can be stored for many weeks in a sealed container, but eventually it will harden by itself if not hardened by CO2.

Look up the method on the Internet, lots of info available.
DavidF
Posts: 282
Joined: Wed May 14, 2014 12:28 pm
Location: Delaware

Re: Baking Cores

Post by DavidF »

and if gassing the SS bound core just is not your thing, you can buy a catalyst to cure it here.
http://shop.clay-planet.com/metal-casting.aspx
jlakes85
Posts: 228
Joined: Thu Feb 23, 2012 6:07 am

Re: Baking Cores

Post by jlakes85 »

I have a 2 part resin system I'm using already. Baking is optional but I dis it to harden them up even more. I screwed up in using an old baking pan which wasn't dead flat. I was hoping there were oven safe surfaces/slabs that are good to use to maintain a true surface while baking
User avatar
Bill_Cook
Posts: 535
Joined: Sat Jan 04, 2003 10:28 pm
Location: Walnut Bottom, PA, USA

Re: Baking Cores

Post by Bill_Cook »

The cores that get baked in the foundry I work in are baked on what appears to be clay slabs. They are heavy and brittle. I wonder if ceramic tiles would work.
BC

If there was only one way to do each machining job, the smell of sulphurized cutting oil smoke would have fewer fond memories.
User avatar
liveaboard
Posts: 1971
Joined: Sun Dec 08, 2013 1:40 pm
Location: southern Portugal
Contact:

Re: Baking Cores

Post by liveaboard »

My wife is a ceramic artist; a kiln shelf is a flat slab of refractory ceramic that stays stable and stiff through high temperatures and is made to cycle many times.
They seem to be very flat; I don't know if you mean machinist flat, I haven't ever checked them.

They're inexpensive and available from refractory supply shops.
optigman
Posts: 124
Joined: Wed Jul 15, 2015 11:17 pm

Re: Baking Cores

Post by optigman »

I have not heard of anybody baking cores for years! Are you making traditional oil sand cores? If so you need to bake them on a flat surface if the core is flat. If it has an irregular shape you will have to make what is called a "bedding frame". The bedding frame gets rammed with green sand, compacted hard. A suitable talc parting is liberally sprinkled on the bedding sand. The oil sand core is then placed on top of the bedding frame sand with parting agent. The bedding frame supports the oil core while it is curing and holds its shape until properly baked. If I were you it might be best to use a more modern core sand that does not require baking. Call a foundry supply and seek their advice on what types of core sand best suit your needs. Good luck with your castings. Optigman
reubenT
Posts: 107
Joined: Wed Dec 24, 2008 11:04 pm
Location: Spencer TN USA

Re: Baking Cores

Post by reubenT »

The recipe I have for core sand is 90% sand and 10% white flour, dampened with water that contains 10-20% molasses. Baked till dry and used immediately so it won't soak up moisture from the environment. I would think ceramic floor tile would work fine for baking plate. Long as it really is kiln fired ceramic and not some imitation. No different than baking bread, smells like good bread too. Might be hard on the teeth.
Post Reply