As others have said, the fusion of the two billets is a mechanical one. For it to be fused, the wire coming out of the die would have to be molten. That is the only way that something that is two pieces can become one. If it were molten, your wire would not be round anymore, which negates the point of using wire. As others have suggested, if you want a 20 pound spool of continuous wire, you need to start with a 20# billet of lead. There is some math and calculations involved in this process. It's not just a matter of using a bigger billet. Fortunately, Corbin takes the guess work out of the process for you with their handy lead extrusion calculator.
Check out the attached image. If you made a lead ingot 2.5" in diameter and 10" long, you would have a 20.1# ingot, so in theory you could make your 20# spool of wire. But look at the kind of cylinder you would need to drive that. 6" in diameter with a 15" stroke. That's bigger than the cylinder on a log splitter. Plus you would need the pump to drive it and the motor to drive the pump. Not saying that's impossible, but it's not a "desktop" set up. That is a serious unit. Corbin's standard hydro press has a 3.25" cylinder with a 6" stroke for comparison.
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