Re: Wire EDM

David Howland wrote:

> From: David Howland <dhowland@...>
>
> Can someone explain how wire is fed in a wire EDM, and what method is used to reduce the possibility of the feeding wire welding itself to the feeding mechnism? As the wire leaves the spool, what does the wire see as it travels to the work (from the spool through the mechinisms and to the work itself)? How does the machine know of problems with the wire, or when the wire runs out? Does the wire rotate to maintain shape in the work?

I'm no expert in wire EDM, but I think I know what these machines are doing.
The current on the wire is not very large, so welding of the wire to the rollers is
not likely. As long as the wire is tightly held to the rollers, but is not quite touching
the workpiece, then all the energy will go into the discharge between the wire and the
work.

Between the spool and the work, the wire travels over some rollers, first in air, then
finally in the EDM fluid. If the wire runs out or breaks, a simple tension roller could
be set up to hit a microswitch.

No, I don't think they rotate the wire. After one pass, the wire is discarded, usually.
They use a LOT of wire, so it doesn't stay in one place very long before it is past
the area where cutting is going on.

As for autothreading, some machines have this, it sounds pretty tricky.

Jon