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Do you inoculate your iron?
You probably do, since it is an essential part of most foundry operations. Aside from reducing chill, inoculation promotes the uniformity of properties throughout varying section sizes, as well as improves machineability and strength. Calcium bearing 75% Ferrosilicon is a common inoculant. In addition, there are several proprietary inoculants on the market.
Control of this inoculation practice is very important. The correct technique must be used to obtain satisfactory and consistent results.
Let's look at some basic procedures of an inoculation practice.
Do's and Don'ts of Inoculation Practice
DO:
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Keep the inoculant dry.
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Accurately meter the amount of inoculant addition by weight or volume.
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Properly weigh the amount of metal to be inoculated.
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Devise mechanical or automatic means of adding inoculants to the ladle.
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Check the efficiency of gray iron inoculation by chill tests taken at the pouring station.
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Code castings so that they can be related to test pieces.
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Remove all slag from the metal surface before making the inoculant addition.
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DON'T:
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Make unnecessary large additions of inoculant.
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Attempt to inoculate metal of low temperature.
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Hold inoculated iron for varied or prolonged periods.
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Collect metal test samples from the immediate surface of a ladle of metal.
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Rely on melt department personnel to make regular additions of inoculant while collecting metal from the furnace.
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Place inoculant in the bottom of an empty ladle that is to be
refilled.
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Submitted by Tom Davies and Mike Morrison; Carpenter brothers, Inc.
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