Re: Software for wire EDM control?

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Graham Stabler" <eexgs@n...>
wrote:

> OK stupid question:
>
> If the CAM program outputs x,y,u,v and u,v is the co-ordinate

system

> for the other end of the electrode and you use a controller program
> that can handle 4 linear axis then what is the problem? Surely the

g-

> code sorts out the syncronization??
>
> Perhaps I am being thick?
>
> TurboCNC allows upto 9 linear/rotary axis BTW.

You have understood the mechanism, now in practice other factors come
into play.

1) Maintaining cutting conditions
2) Avoiding wire twist.
3) Recovering from a broken wire

The CAM program takes care of the wire positions so the wire does not
twist and get caught in it's shorts. This includes approach and
depart strategy, glue stop, multiple passes, cutting condition
settings(this is often set at the console by an operator, depending
on machine builder).

If you are familiar with surface modeling, the shape cut by a 4 axis
wire EDM is very similar to a ruled surface. Many shapes that cannot
be milled or broached are very easy with this process. There are
limits to the size of the taper angle that can be maintained (based
on material type and thickness, wire size, condition of machine and
guides, etc, etc, etc). There are also some undesirable things that
happen when a sharp corner is at the top and a large radius is at the
bottom. The controller can be directed to cut it correctly, but it
will still burn the "h" out of the top sharp corner while swinging
around the large radius at the bottom.

Wire EDM almost always uses "cutter" comp ( wire radius comp
actually), because the same cutting path is programmed over and over
with changes in power level and offset radius to fine tune the size.
(multiple passes) Most of these machines in the commercial world
program with 5 decimals in inches. Think about cutter comp with .005
wire if you only use 3 or 4 decimals. Lots of chance for strange
things to happen, that don't happen if the rounding is at the 5th
decimal instead of the 4th.

Fred Smith - IMService