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Subject: Camshaft porosity
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Date: 03/20/02 at 5:25 PM
Posted by: Mark Herbert
Dear Experts, I work in an Australian Foundry, we are currently experiencing high porosity scrap levels in our camshafts that are made in green sand moulds (george fischer air impact)and poured via an autopour furnace, the sg iron is treated in the ladle after it has been tapped out of the medium frequency furnace then transferred to auto pour furnace.
This is a problem that has been coming and going for years without warning, even when our analysis specifications are met.
Our technical people (metalurgist) have had little success determining the root cause.
Is there any suggestions as to what causes this porosity? (pin holes usually on or just beneath the surface)
Can you suggest any changes to the specifications or process that may overcome this?
Any suggestions would be greatly appreciated.
here is our metal specifications for camshafts
Cr =0.15 max
Al =0.009 max
Ti =0.040 max
pour temp = 1430-1450
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