Rule
No. 6:
"Avoid Shrinkage"
Feeders can't feed uphill. (Well, actually, they can, but
not reliably.) (See also Rule 7). Feeding downhill, aided
by gravity, is safe. Thus feeders (risers) preferably have
their tops well above the top of the casting. (Click
here to view diagram of a feeder correctly designed to absorb
shrinkage.)
Ensure that feeder design is as reliable as possible. Therefore:
(1) Check that the design follows all the Feeding Rules
(see book "CASTINGS"
by J Campbell, Published by Butterworths 1991), and
(2) Use a reliable computer modelling package, and
(3) Check test castings by X-ray radiography (or somewhat
less reliably, by cut sections).
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