I was just wondering if a person could do thier own extrusions at a home or small shop. What kind of machines/equipment is involved?

I believe extrusions are poured, using a mold and extremely large foundry equipment. This partly where the word wrought is derrived from.

But then I could be wrong.

Aluminum extrusions are made in an industrial sized Play Dough type machine. The raw aluminum comes in a billet, which is a big cylindrical chunk of aluminum. This billet is melted and squeezed through a die plate. (This is a flat plate which has the shape of the extrusion cut into it.) The extrusions are run out to about 100 feet long and cut off.

They come out kind of twisted and bowed. Each end of the extrusion is put into a vise and stretched and manipulated until straight. The long lengths are then cut down to 12' sections and put into a heat treat oven overnight for hardening.

The next day any secondary operations, drilling, cut to length. etc can be done.

Excess aluminum is remelted into billets for reuse.

There are tremendous pressures involved and the equipment is huge and expensive. Could a hobby size extruder be built? I am sure that it could be, but if you have enough extrusions to warrant the costs of building a machine, then you'd have enough volume to purchase them, even if you had to buy custom tooling.

I recently visited an aluminum extruder. It was very interesting to see. buscht's explanation is almost exactly the way it works, with a few exceptions. The only difference I saw was that the extrusions came out very straight. From talking with Mike (the owner), die design is very important. He has 35 years of experience in die making and it still takes them 2-3 times to 'tweak' a die to give good, straight extrusions without the twisting and bowing that can easily happen.

Hobby size extrusion setups cold be made, but plastics/clays would be much easier to extrude than metals. In order to plastically deform metals, huge forces/pressures are necessary. Just guesstimating, I'd say you could set up a small scale aluminum extruder, let's say 3" max diameter, for less than $50,000.

Well...let me just find my checkbook and...

Great, just what I need, one more project to think about!

This was a good question, and I think it could be done on a homebrew scale. I'm not exactly sure how... maybe a big hydraulic cylinder, plus a variation of a homebrew foundry (which I have)... The trick is in the squeezer (that's a techincal term). You would need very tight tolerances and/or seals of some sort and good control on the temp of the Aluminum so it doesn't squirt out the wrong place!

Depending on the length of extrusion a person was after, it may or may not be worthwhile to build one. If you don't need very long pieces with smooth surfaces, you could get some shapes with lost foam casting, just not as nice!