risers chills and sand casting, question.


Bramblebush ForumsFAQ

Posted by Rob Frink on April 04, 1999 at 15:04:34:

I'm struggling with a pattern design that has a thick(massive) section between two smaller sections. The overall piece is "long" in comparison to the width. Its the oposite of an hourglass. Anyway, I can't seem to get enough riser mass to the center section to keep feeding it while the ends freeze. The runners from the riser freeze and aggrevate the problem of a sunken center. I really can't make the runners any larger than what I've tried. I tried casting the piece horzontal with a large riser head next to the center, but no good. Then I tried casting it vertical without a riser but and exceptionally tall sprue for pressure gated at the bottom. The fill was very nice and quiet this way, but still had a sunken center after cooling.

I think I should try a chill but I'm not really sure how. The pattern is full of gracefully irregular curves. It will be very difficult to make a chill that conforms to the pattern. Is it effective to "bury" a heat sink in the sand next to the area to chill? I'm thinking about a block of brass. There will be a thin wall of sand between the mould and the sink to maintain the pattern shape. Will the thin wall of sand allow heat to transfer from the mould to the sink?

Does anyone have any ideas? This has got to be a very fundamental problem that has a simple solution.

Thanks in advance.


oh!......the metal is Si Bronze.

Follow Ups:

Bramblebush ForumsFAQ