"Training" materials for learning to do wire EDM programming in Creo

Like I said in my original post I’m doing simple 2-D stuff fine. The problem I want to address is to get the appropriate geometry created for 4-axis (X,Y,U,V) programming. The difficulty with this situation is it’s not simple geometric entities, i.e. line → arc → line → arc → arc ...etc. motions being created to follow the path. A true 4-axis path consists of points for each curve, completely synced up for two curves, one at, typically, Z = 0.0000, the second at the Z height of the upper head. The machine only works, as far as I can discern, with point-to-point motions. The curves comprising the path the upper and lower head need to traverse must result in the exact same number of points, each lower point synced with its corresponding upper point.

For the machine I’m using, and probably most machines, the X,Y coordinates in the resulting G-code file are the positions the lower head moves to, and the U,V coordinates are the offset of the upper head from the lower head.

The way I’ve been approaching this is to define sketches at the upper and lower head planes, with curves that correspond to each other in both planes. I do some calculations to determine the number of points needed for each curve, based upon curvature and the maximum allowed deviation. Build sets of points along each curve on both planes, using the calculated number of points for each curve (i.e. line → 5 points, arc/spline → 10, 22, 40, whatever meets deviation requirements). Same exact number of points in upper and lower plane. Then I output the points to a file, read them into an Excel file, which outputs them as the correct geometry G-code.

I was hoping there were some sort of demos of the wire EDM capabilities in Creo, but apparently this particular “functionality” is as updated and modern as a 1999 Chevy Caprice. Seems like for the most part people are doing 2D cuts with these machines. Understandable, they’re awesome at doing that kind of thing. But for me I’m in a situation where I need to do tapered cuts that are not a simple “apply a taper to the motion and let the machine take care of it” operations. I’m cutting parts out of a rough block and need the wire to cut normal to the surface contour, or other spline-driven geometry. I can create the geometry and process the points to get good programs, but it’s kind of tedious and not something easy to pass off to someone to program in MasterCAM.

I suppose I’ll have to take a harder look at the 4-Axis capabilities of Creo and evaluate whether it will be able to maybe make my job easier. Post-processing will be hellacious.

The other troublesome part of this is for the machine I’m working with, GF (Agie/Charmilles) type, operation is not with a simple G-code file. The machine uses what are called “job files” (.mjb extension) which consist of a top-level control  section, pre-cut setup section, and geometry files. The G-code is used as “geometry”. All the parameter setting, initial positioning, wire thread/cut etc. are done prior to using the G-code. You can put such things in the g-code, to some degree, but most preparations need to be done in the setup section. The .mjb file is a big messy XML format file so a post-processor that was zero-touch would have to put out the correct contents, which are pretty opaque to me. Settings relating to the size and type of wire that are specific to the each machine, technology table specifications with hundreds of parameter settings, etc.. Punching that stuff out correctly is going to be a nightmare. But that’s a problem for the future.