Molds and molten metal...

[Oualawouzou]

Hello everybody,

I know the answer must be simple, but I've been thinking about this problem for days and haven't been able to find a good answer.

I understand that molten metal is poured into containers made of materials that have a melting point superior to that of the metal. To create that container, you will need molds or tools made of a material that have a higher melting point than it, so that you can properly shape it without destroying your tool/contaminating the original material. But these tools ought to be created using other tools with a melting point higher than... etc.

Obviously, something's not quite right in the way I picture the situation. Help! And thanks.

 

[LTC8K6]

Fire brick can be shaped with ordinary tools, yet can withstand temperatures that would vaporize those tools.

Ceramics, too.

 

[Ziggurat]

Concrete is another example: you don't shape it by melting it.

 

[Oualawouzou]

I knew there had to be a fundamental flaw in my reasonning. Thanks guys!

 

[Hawkeye]

Your mistake is to assume that metals need to be molten in order to be shaped.
Sintering^WP is a method for forming metal objects from powder, without the need to melt them. Typically sintering is done at about 75% of the melting point of the metal - which translates into a lot of money saved on heating bills.

Ceramics, by the way, are almost exclusively made by sintering. The few notable exceptions include glass and concrete.

 

[Crossbow]

Sand casting is a great way to form molten metal into all sorts of shapes for several reasons, one of which being that very simple tools can be used to shape the mold.

 

[ponderingturtle]

Hello everybody,

I know the answer must be simple, but I've been thinking about this problem for days and haven't been able to find a good answer.

I understand that molten metal is poured into containers made of materials that have a melting point superior to that of the metal. To create that container, you will need molds or tools made of a material that have a higher melting point than it, so that you can properly shape it without destroying your tool/contaminating the original material. But these tools ought to be created using other tools with a melting point higher than... etc.

Obviously, something's not quite right in the way I picture the situation. Help! And thanks.

Fundamentaly you do not need to melt a substance to shape it is the mistake you are makeing. You can have something that is undergoes chemical changes, like say plaster or concreate. You can also use mechanical methods to shape a mold, such as drilling and carving.

One standard way to make a mold is to make it first in a soft substance and cave the shape say wax, mold it in plaster, melt the wax and add the metal.

But anyway you can shape something can be a method of makeing a mold.