Casting Aluminium (not aluminum, you yanks just cant spell gooder!!!!)

[fabr]

A plastic material that is used in place of many of the metallic internal engine parts now. Very tough and very wear resistant. Do a PEEK search and read about it.

[artie on edge]

A plastic material that is used in place of many of the metallic internal engine parts now. Very tough and very wear resistant. Do a PEEK search and read about it.

Thanks mate, done!

[Boostinjdm]

question for ya artie.  Is it possible to make a reusable mold out of steel or something that is easy to come by?  Or do you need the insulating properties of the sand?

[artie on edge]

question for ya artie.  Is it possible to make a reusable mold out of steel or something that is easy to come by?  Or do you need the insulating properties of the sand?

Yes its possible but not for something with an internal pocket. The shrinkage in ali is much more drastic than with steel so if you need a hole, the ali would shrink ONTO the mold and be fixed permanently.

The ingot molds for example are channels of large angle iron welded to two plates at the ends. The ali heats the mold to a dull red and then simply falls out because it shrinks more than the mold when nearing cool.

The ali semi crushes the internal sand shape as it cools so whatever you use has to have good thermal properties and be flexible when required but stable enough to be able to make complex shapes.

If only it was easy.... :-\

[artie on edge]

Just thought on that some more.

You could make the external shape (say of my final drive) out of steel and the internal shape of sand.

The ONLY real problem with that is it would need to be preheated as the steel would absorb large amounts of heat from the ali and could disrupt the smooth flow of molten metal.

I think it is possible though.

But in reality, making it from wood and making a mold from sand is easier..imo

[Camel]

[artie on edge]

Fantastic! Thanks mate Ill drop in at lunch and see what ive got.

[artie on edge]

These are the ingot molds I use. As I said simply angle iron welded to two ends plates. Hold just under a litre each So one crucible pour per mold fill. Gee I wish they were gold.... :-[

I got 10 ingots from 2 extinguishers, 6 more left with more coming...

[artie on edge]

Thanks to Camel I now know that almost all the extiguishers I have are T6061, one is T7060 and bugger me if it isnt corroded around the neck (white powder coating). Its to be set aside.

The material that comes out of the crucible is initially heavy with dross. This comes from surface impurities that go into the crucible, such as paint on the item being melted or any other contaminants. (dross is like an oxidised crumbly ali mix that floats on the surface, its simply skimmed off and discarded)

Therefore I always 'ingot' the material first and do a good dross skim before I pour them This then leaves really pure ingots so when I go to cast anything the dross is minimal.

The extinguishers have to be 'sectioned' as they wont fit into the crucible in one go and anyway would overflow it. I used an old bandsaw with a coarse blade to chop em up into sections. Took only a few minutes per unit.

[Boostinjdm]

Is there any other reasons for doing ingots other than the skimming for purity that you mentioned and storage?

[artie on edge]

Is there any other reasons for doing ingots other than the skimming for purity that you mentioned and storage?
[/quote

Thats about it..... 

[Boostinjdm]

so let's say you have smaller pieces of brand new material....would it be worth it to poor ingots or just melt it down when you are ready to do your casting?

[artie on edge]

It depends upon how the material was formed. For some reason any extruded material seems to have a hard skin on it which equates to quite heavy dross. So those I would do before hand.

Any cast or billet stuff you could do on the day I guess.

When you are set up to cast there is a hell of a lot to do in a short time window. Therefore taking care of 'maintainenance' stuff before hand makes sense.

Note the height of the mold. Too close to the concrete can/will lead to 'spalling' (concrete surface exploding... fun.. not..).

Or do it on heat bricks (I use ceramic pavers)...

Besides, its fun 

[Doug Heim]

where does the heat supply come from? and what is the operation and involvment. With all that swarf I have Im starting to brainstorm. 

[Camel]

where does the heat supply come from? and what is the operation and involvment. With all that swarf I have Im starting to brainstorm. 

   Ha!  Thought you might!  Here come those rear uprights!  You'd better be quick though......

Artie, are you using a waste oil furnace?

Where do you source your crucibles?

And isn't bentonite (kitty litter) a better option than oiled sand?

Camel