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The statement "Note that internal chills will absorb both heat capacity and heat of fusion energy" seems to imply that external chills will not absorb the sensible heat and the latent heat of fusion. I think that is not presenting the external chill properly. I don't see how an internal chill would be an advantage in this way. The internal chill does have an advantage in that a specific, highly localized, heat extraction can take place. Obviously the internal chill is more effective in that it is sacrificial (often) and when sized properly, the internal chill itself may undergo melting and in this the heat of fusion associated with that happening to the chill is beneficial to the cooling of the casting it is used in. If that is what is being described I think some diagrams or a better way to describe the transfer process is needed. In addition, internal chills are often not used because they can introduce defects in the casting in the very area where soundness is being promoted, due to oxidation or moisture presence on the chills. This can happen with external chills as well but the internal chill is more prone to the problem. Also the internal chill has a disadvantage in that it is used only once. The external chill can be used many times. Mfields1 (talk) 00:09, 22 June 2009 (UTC)
Perhaps its not worded the best, but an external chill cannot absorb so much heat that would cause it to melt, AKA it does not absorb the heat of fusion. As for the internal chill, you are correct in the way that you described it above. Pictures are always a good thing, but short on supply. As for the reasons why certain ones are or are not used, please add them to the article. Wizard191 (talk) 01:51, 22 June 2009 (UTC)