Chills in cast iron

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4catmom

Chills in cast iron

Post by 4catmom »

Does anyone have experience making iron castings with chills? This would be to produce a white iron surface on certain areas of a grey iron casting. Is the part of the mold creating the chill typically made of steel, cast iron, or what? What type of coating is used to keep the casting from sticking to the mold?
jpfalt
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Joined: Sun Jan 05, 2003 12:55 pm

Re: Chills in cast iron

Post by jpfalt »

For cast iron, either iron or steel would work. The chill has to be relatively massive compared to the casting to drop the temperature quickly on the casting surface and keep it low enough to avoid having the white iron tempered or normalized out as the casting continues to cool. As the casting cools, it heats up the chill. if the chill goes over about 350 degrees, it will begin to temper the surface and you will not get full hardness.

As a release, use a graphite wash made by mixing graphite and isopropyl or denatured alcohol and spraying the chill and mold surface. Use alcohol with as little water mixed in as possible. Then light the mold surface with a torch and burn off the excess alcohol to leave a dry graphite coated surface. If wet with either water or alcohol, the liquid will flash to steam when the metal hits it and ruin the casting.
4catmom

Re: Chills in cast iron

Post by 4catmom »

Thanks for the info. I'd like to try this sometime.
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Adirondack
Posts: 410
Joined: Tue Aug 23, 2011 6:59 pm
Location: southern CT

Re: Chills in cast iron

Post by Adirondack »

jpfalt wrote: Wed Jul 20, 2005 5:19 pm For cast iron, either iron or steel would work. The chill has to be relatively massive compared to the casting to drop the temperature quickly on the casting surface and keep it low enough to avoid having the white iron tempered or normalized out as the casting continues to cool. As the casting cools, it heats up the chill. if the chill goes over about 350 degrees, it will begin to temper the surface and you will not get full hardness.

As a release, use a graphite wash made by mixing graphite and isopropyl or denatured alcohol and spraying the chill and mold surface. Use alcohol with as little water mixed in as possible. Then light the mold surface with a torch and burn off the excess alcohol to leave a dry graphite coated surface. If wet with either water or alcohol, the liquid will flash to steam when the metal hits it and ruin the casting.
For anyone following this topic, I just ordered some of this https://www.superior-industries.com/pro ... -5500.html to use as a mold release for my chilled wheels.

Chris
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Glenn Brooks
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Re: Chills in cast iron

Post by Glenn Brooks »

One thing to keep in mind- chilled cAst iron is nearly impervious to HSS and Carbide. Apparently you have to grind the wheel profile if you need to clean it. Hence the casting needs to come out of the mold near perfect to have a useable wheel. Some people post heat the chilled intron to make it soft enuf to machine. Must have been a real art in the old days.

I offered to turn some chilled wheels for a friend last summer, and couldn’t even scratch them…


Glenn
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Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....
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