Chill Bar

Linked documents or member created reference materials, good reading for when its raining.
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mite5255
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Chill Bar

Post by mite5255 »

On Dave's thread Cincinnati Shaper Jerry mentions a chill bar, my question is, when, where, why and how do we use a chill...Seeing that I'm hoping this will end up being more of a instructional thread I decided to place it here in the library

Mike
When life gets tough, remember: You were the strongest sperm :)
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Jammer
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Re: Chill Bar

Post by Jammer »

https://en.wikipedia.org/wiki/Chill_(casting)

Here's a little article about them. I'll have to look through some of my books for some pictures and more info.
quando omni flunkus moritati 8-)
mite5255
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Re: Chill Bar

Post by mite5255 »

Thanks Jerry
When life gets tough, remember: You were the strongest sperm :)
dallen
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Re: Chill Bar

Post by dallen »

they are used to help with controlling solidification of the molten metal to help with shrink cracks and such, like Jerry said you would have to read up on the subject to get a good grasp of the subject.

one example would be were you have a casting that has some thick sections which when poured will cause shrinkage defects by cooling off too late and can't be fed with a riser of shrink bob, but can be made to cool down faster then normal so that the thick section doesn't cause problems.

Hope I got that out so that it's understandable, I'm 100% sure that Jerry will do a hell of a better job at explaining it then I can.
David and Charlie aka the shop monster

If life seems normal your not going fast enough" Mario Andrette
F.C.
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Re: Chill Bar

Post by F.C. »

When I use a chill in my castings the size of the chill is directly proportionate to how quick I need a specific area of the cast to freeze first. Often the gating is mandated by the shape of the piece to get metal where it's needed the quickest and cover all cavities in one pour but often that routing can leave a thicker area farther away from the pour cup abandoned by the bulk of the heat of the melt the gating and pour cup retains. Yes, additional reservoirs can be added to accommodate the necessary thicker fills and keep that area fed as it cools but there are times where one area of the cast may have sufficient thickness that may compete with other areas of the cast as both cool down which would, or could, tear apart a section in the form of a crack. We need to recognize those variances in the pattern first (or study hard a failed cast) before we attend to creating the gating initially or on a second attempt. In situations like that the gating can be thickened (nearest to that section) to fill that overly thick area and still allow for "some" melt in the gate to continue to feed that section as it's cooling and shrinking but if it's too thick you stand the risk of the two thicker areas of the cast to compete for fill as they both cool and shrink. To stop that you do both... thicken the gating nearest the second largest largest section of the cast (to act as a minor reservoir) but also add a chunk of "cold" steel (a piece that's been in the freezer a while) packed loose (not connected to the cast) roughly 1/4 to 3/8 inch from that section in the sand mold. This will cool that section of the sand and keep it cooler as the metal's introduced which will control that area of the cast to cool "FIRST" (but not overly quick) and allow the middle thinner sections of the cast to chill at their normal rate, then your thickest piece can either draw from the pour cup's reservoir or from a secondary reservoir you might care to add to that section (in addition to the gating) or as part of the gating itself near to that thicker piece or even connected with a thicker gate tab.

All a chill entails is a piece of "COLD" metal packed in the sand next to an area of pattern (the cast) you wish to cool first in the sand. If it's extremely hot metal like iron go with a thick piece of hard steel. Same with bronze. If it's aluminum I use a 1/2" chunk of hardened aluminum plate roughly 1"x2"x1/2". Maybe a couple pieces if I feel two would work better. Like I said, it's all about cooling that particular area of the sand mold more than the rest of the sand. Aluminum sucks heat quick, steel and iron much slower.

Hope that give you some insight, Mike.
mite5255
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Re: Chill Bar

Post by mite5255 »

Thanks Dave and Frank, that explains it well, I''ll do a test sample, one with and one without a chill when I get back into the casting caper, at the moment I'm still off work, but I do, do some scratching around in the shed doing light work, such as new flasks and getting a few small jobs ready for casting, just trying to keep my brain working. Hope to fire up next week. Dr has told me to really watch what I do and try and take it easy with any lifting
When life gets tough, remember: You were the strongest sperm :)
dallen
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Re: Chill Bar

Post by dallen »

Franks explanation is much better then mine. But to make a short story out of a really long subject, it takes a lot of trial and error for home shop guy to figure out most of it.

I doubt that the casting that I do will ever require a chill
David and Charlie aka the shop monster

If life seems normal your not going fast enough" Mario Andrette
mite5255
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Re: Chill Bar

Post by mite5255 »

Yes Dave, I have no doubt that there's a heap of learning on how to use the chills in the correct manner for the home foundry
When life gets tough, remember: You were the strongest sperm :)
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