Re: Casting long cooling fins in petrobond


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Posted by John Odom on January 04, 19100 at 08:39:36:

In Reply to: Casting long cooling fins in petrobond posted by Lyle Landstrom on January 03, 19100 at 14:59:21:

One way to do it, the way most industrial foundrymen would recommend, is to form the fins with cores. Make cores for the spaces between the fins. One core box can make all of the cores for the spaces. The cores are rings shaped like the spaces between the fins, with a shallow "V" on the outside diameter. The main pattern just has matching wide shallow "V" groove core prints at the center of the space between each pair of fins, and a ring-shaped core is put in each "V"


I made a casting for a large 2-cycle model airplane engine cylinder many years ago and finaly had to do it that way.

Sometimes changing the gating so the metal won't abrade the sand so much can be enough, and let you avoid the loose core pieces. Before making new patterns, try gating so the liquid aluminum feeds from the bottom of the cavity, slowly rising with the bouyancy provided by the metal supporting the (weak) projecting sand fins.

Air-set or silicate/CO2 bonded sand might help too.

Hope this helps.

John Odom, in Ooltewah, TN

Poor ASCII art:

*= Gated Path of Metal


* ___ | | ___

* ___| | | |___ Casting with fins

* ___| | | |___

* *|__|

*********** Core for cylinder bore

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