Heatsink die-casting

[JayV]

What do you think? Will this work for aluminium casting?

This is an simplified model just för explanation:

The blue and red is 10mm sheet steel, and the green 3mm.
The grey parts is screws.

[JayV]

Now the front and back plate is attatched to the die.. You pour aluminium in the tube.

[JayV]

The result when you remove the back and front plate to get the heatsink out is this... Remember this is just for example

[JayV]

With a litte better spacing and the fins should look something like this... Every fin is 3mm wide and 50mm deep.. the heatsink is 300*150*60mm, and the front area is about 40dm2... What c/w could i expect from this? Will it be enoug if i use 2 of these heatsinks for one aleph2?

[Ilianh]

I just wonder, would'nt you have to preheat the "mold" to a certain temp or having the aluminium at extreme temperatures?

I'm sorry to be a little off topic here, but how would you melt aluminium?
And if I remember well, when aluminium melts there was a problem with hyrdrogen having to be removed (and oxydes too) using some gas (was it chloride?)


I'm just curious because I had a similar idea not long ago.

[JayV]

its not to hard to melt aluminium (660 degrees celsius or something like that). search for "charcoal foundry" on altavista or some other engine! seems to work fine!!

[Sch3mat1c]

Much easier to use a sand mold in place of the metal mold. You have to do all sorts of stuff to make sure the metal even fills the mold, much less solders/brazes itself to it, and clears it (draft and finish). Only problem with a sand mold here would be sand breaking inbetween the fins; a hardened mold (bake/no-bake) would fix that.

Tim

[JayV]

i don't like the surface from sand molds... :/ and i don't think it will be any problems with the fin "pockets" as they are 150*3 mm the air should be able to vent! perhaps i could make them 4 or 5 mm instead just to be safe.. and some small vent holes on the top plate...

[faustian bargin]

i know next to nothing about aluminum casting. but it seems to me you might want to consider slightly tapering the fins; first it helps prevent trapped air, and second it makes the mold easier to remove once it's cast.

good luck - i want to see how it turns out.

sch3matic did you ever have any luck with your sand cast heatsinks? if so i'd like to see pictures.

/andrew

[JayV]

perhaps i just make a prototype with 2 fins just to see if the aluminium will fill out nice and how the surface turns out... it should be easy to remove the heatsink from the mold as you just can dissasemble it all

anyone here who is experienced with casting in steel dyes?