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View Full Version : would blue insulating foam work ????



smokieborde
12-25-2005, 05:12 PM
if ypu milled out the shape in foam
like house insulating foam
and then washed it out with acetone or zylene
do you thinjk that will work
useing wet sand mold after drying out the mold

Geof
12-25-2005, 06:42 PM
if ypu milled out the shape in foam like house insulating foam and then washed it out with acetone or zylene do you thinjk that will work useing wet sand mold after drying out the mold

Are you wanting to do lost foam casting? The typical procedure is to take a foam pattern, dip it in a clay slurry to get a coating that very accurately matches the surface of the pattern, dry the slurry and then pack it in a sand mold. The molten metal is poured in and vaporizes the foam.

It sounds like you are trying to mimic the burnout procedure that is used in lost waxing casting where the wax is removed in a baking procedure. You want to dissolve the blue foam out with acetone or xylene. I think you will finish up with a sand mold saturated with acetone or xylene. Both of these are flammable so life could get interesting when you filled the mold with molten metal. By interesting I mean you stand a chance, depending on how large your mold is, of levelling your workshop.

I think you should stick to regular polystyrene foam for lost foam casting; I think the blue insulation foam contains fire retardants so it is probably not suitable as the whole purpose of these is to stop the foam melting and burning and they would interfere with the foam vaporizing way ahead of the molten metal.

dufas
12-26-2005, 01:32 AM
There is also the chance that the blue foam is polyurethane. The white polystyrene foam is the only safe way to go. I use white spackling compound watered down to a milkshake consistancy to coat the foam with. It usualy takes over night to dry. If I were you, I would make some test peices first to get the hang of what to do before trying anything serious.

the best place that I have found form ameture lost foam casting of aluminum is

http://www.buildyouridea.com/foundry/lost_foam_howto/lost_foam_howto.html

His pages have a fair amount of info

RBrandes
12-26-2005, 06:19 AM
Smokie,
Lost foam is a great way to make castings. I have made several aluminum things and also bronze lathe tool holders this way.

White foam is the best, but you can use blue and pink. However they generate more gas than the white. Don't ever try that foam in the can stuff. Way too dense and very nasty fumes.

I fabricate my paterns using a hot-wire cutter and join the pieces with hotmelt glue or masking tape, both of which burn out. If your first try doesn't turn out, try again. There is some art to this.

The link posted by Dufas is a good one. Here is my page on the subject:
http://www.ray-vin.com/casting/lostfoam/lostfoam.shtml

See my general pages for more casting etc at:
http://www.ray-vin.com/frtech.htm

Regards, Ray

nffsflyer
12-26-2005, 10:35 AM
Ray's use of hot melt glue or masking tape to join pieces of white foam sound good. A friend who does lots of lost foam casting (I haven't yet) had asked me about joining foam pieces; I suggested he try a light mist coat of 3Ms "77" spray adhesive. He tried it, and said that the "77" is the very best method he's ever tried.

And thank you for the links provided!

Bob Beecroft
Fallbrook, CA
______________________________________________
I fabricate my paterns using a hot-wire cutter and join the pieces with hotmelt glue or masking tape, both of which burn out. If your first try doesn't turn out, try again. There is some art to this.

The link posted by Dufas is a good one. Here is my page on the subject:
http://www.ray-vin.com/casting/lostfoam/lostfoam.shtml

See my general pages for more casting etc at:
http://www.ray-vin.com/frtech.htm

Regards, Ray

smokieborde
12-26-2005, 11:13 AM
thanks guys

it was just a brain storm thought
never tried it
just thought it would leave less foam to burn out

it would probally take a long time to
everratorate fumes out of sand
dont wont no explosions

ed

zuk123
12-27-2005, 06:32 PM
I have used blue foam for lost foam casting of aluminum parts without trouble, by just packing the foam shape into the sand. It has the advantage of smaller grain, and is easier to get detailed shapes than white. Definitely want good ventilation though.

The art/ sculpture dept. at ASU used this technique extensively in the late 80's. They may have abandon it by now, but it worked great then.