We produce alloyed aluminum ingots for foundries to re-melt and make functional castings.  To make the ingot shape the molten metal comes out of the furnace tap hole into the mechanism that distributes it to each ingot mold as they come by on a continuous conveyor.  The mold conveyor takes the filled ingot molds to a water spray area to quickly cool down the molten metal and to solidify the ingots.

Some times the ingots get a stain or discoloration instead of the usual bright shiny silver color.  The color is usually a dull yellow to brown.  Sometimes an iridescent pink/blue, like oil on water.  This colorizing has been described as an oxide layer just a few atoms thick that reflects the light like a diffraction grating, thus the colors.  This is harmless and usually goes away upon re-melting at our customer's foundry.  However, some customers don't like this.  They question the quality of the ingots.

Is there some way we can prevent this from happening, or stop it once we see it starting to discolor our ingots?

Ron Zakrzewski, Laboratory Manager
Custom Alloy Sales

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Ron Zakrzewski
Laboratory Manager
Custom Alloy Sales
CITY OF INDUSTRY CA
16263693641
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