Aluminum casting problem

If you mixed your greensand correctly I would not fool with it. When you cut your sprue and gate and runners are you slicking them down and making it so there are no sharp projections into the mold cavity that can get washed off. At the bottom of the sprue you need to make a deeper impression so the turbulance of the molten aluminum does not cause the sand in this area to get erroded away. Simply make a deeper cavity below the bottom of sprue and also below the bottom of any gate or runner. I think the 10% of bentonite to sand is in the ball park.

70 mesh is pretty coarse so you may want to add just a touch but not all that much more bentonite.

Another last ditch effort is to make a vent riser equal in size to the fill sprue, and tilt your mold so this vent riser is at the higest portion so any loose floating sand is floated up and out this vent riser. Its not a cure but a possible work around. Make sure your ramming the mold sufficiently and slick down the edges of the pattern / mold at the parting line so it does not contribute to loose sand in your mold.

Pouring thinner sections hotter is the normal proceedure. Visit my website:

expressed are those of my wifes, I had no input whatsoever. Remove "nospam" from email addy.

check your gating system. Are you using a pressurized or non-pressurized gating system? What's your ratio for downsprue: runner : ingate?

Tricks to help can include:

• reduce pouring height

• put bigger well at bottom of downsprue

• go to non-pressurized system

• put traps at end of runners

• dog legs in runners/gates

• minimize turbulance and metal veloceties in gating system

Thanks for the link. I suspect the last parameter is the one giving me the problems. My ingate is quite small due to the thiness of the casting. Metal velocity at that point is probably high. I also was trying to keep the hydrostatic pressure high to help fill. My first attempt only filled partialy - but had no sand includions.

check your venting.

What is the smallest cross section of your casting? Can you move the ingate? Faster fill doesn't always make a better fill.

What's the height of your cope?

non-pressurized

The venting on this part has consisted of several small(3/32") vents at the top most portions. They have never fully filled. One can see that the ones closest to the ingates fill to a greater height (around

2 inch) than the colder ones.

Size and general shape of a bread pan - about 4mm thick the piremeter has a section only about 1.5mm thick which has been limiting my gate size. There is a way I can gate to a more substantial portion of the patern but it will take a bit more creativity - and my first attempt at making a core.

Yes. Tried one at one edge and then one on each end. The attempts with 2 had sand inclusions (if that is what they really are) on only one side, and seemed to be of less total volume.

That has been my limited experience. The slower and the colder I can pour and still have a fully filled mold seems to give the best results.

About 6 inches total - 3 inches above the top of the casting. I also tried swapping the cope and drag relative to the pattern with little differance.

Will probably try again this weekend with larger runners, bigger sump under sprue, a sand trap before the gate, and larger gates. I've had good luck with other patterns using a slanted sprue. Seems to allow the metal to flow in with less turbulance. But the flask I have been using is a bit small to try that with this pattern. I have made a slightly larger flask and will use it next time.

What about using a runner and multiple ingates around the edge?

This advice is worth what you paid for it... my foundry work, so far, comprises reading about it

Mark Rand RTFM