Wire dig in at internal corners

[dalt.deuel]

Hi all,

i am getting wire dig in at the internal corners on my burn programs. When i run my 3d simulation everything looks fine. When it is wire burned on our mitsubishi mv1200s (md pro-3)it has dig in. It is occuring on ruled surface burns as well as straight through burns.

I am programming using opticam

4 passes
.008" wire
2 degrees

i have tried to put .005" radii in the corners as well as running them with sharp corners programmed and getting the same result.

Is this a programming issue? Is there a setting on the machine i need to adjust?

Any and all information helps.

 

[Ishira]

When programming your wire path are you accounting for kerf? For width of the wire? My immediate thought is the wire path is too close to the part, so when it reaches the radii it dwells a little too long and burns a little too much material. If you are accounting for both things, then I'm not too sure.

 

[Brian Pfluger]

dalt,

Is the "dig" related to your Rough Cut Offset when it is applied in the machine? Can you zoom in on the control in the trouble area to verify that the offset is not causing an issue? Opticam also has a Corner Avoidance function that automatically changes the geometry to prevent an overcut condition due to a geometry/offset interference, but you will need to be inputting and posting your Offset values from the CAM system. You can also select and output Offset Geometry from Opticam, meaning that the CAM system changes the NC program values for each pass by the Offset amount.

- Brian

 

[dalt.deuel]

I am unsure at what pass the issue is arising. I will see about checking the tool after each pass to disect which pass is causing the issue.

Currently we use the offset
1st pass- .0077
2nd pass- .0057
3rd pass- .0047
4th pass- .0042

(THESE ARE ACTUALLY IN CODE AS H001, H002, ETC. I WAS JUST LETTING YOU KNOW WHAT OFFSET EACH PASS IS RUNNING)

if i select offset geometry then we no longer have control over wire compensation? Am i understanding that correctly? It is not a problem if we lose that control because the form is correct and brought in as a .dwg file from solidworks.

In the past, we have had what appear to be fishtails on the rough pass and the 2nd pass and weve found that if these are present in the corners than the burn gets deformed. Currently, we are not seeing this issue in the corners.

I will look into the corner avoidance you have referred to above.

 

[pr0xify]

I definitely wouldn't put .005 radius corners with .008 wire. Wire offset will most likely make the CAM output a crazy path at the corner. At least thats what happens on ESPRIT if the radius is too small for the wire + offset. Now with sharp corners, it should not be doing this. Unless perhaps you are cutting a die into a sharp corner of a small angle that the CAM thinks the wire will overburn.

Go to your Machining Setting area and check what is input for CM-R. This stands for Corner Master - Roughing and it has adjustments for speed vs accuracy. You could try it on the accurate side which is what I use with no issues. Do you have the correct wire weight/length input from when you installed the spool of wire? Also do you have the WT (wire tension) set correctly? I assume your using one of the Mits Epacks which shouldn't need changing.

If you share more about the part geometry I may be able to help.

 

[dalt.deuel]

this is the wire burn path. THE RED LINES INDICATE WHERE WE ARE GETTING "DIG IN" OR "OVERBURN"

There is 2 degree side clearance. This is a carbide triangle insert. I am not the one running the wire but the one programming.

.125" thick, using mitsu e-packs

mitsu applications engineer told us to use cm-r so that is being used on the machine. As far as wire tension i am not sure i can ask the operator when he gets back from lunch. Do you have a good starting point for wire tension?

 

[pr0xify]

Forget the wire tension comment if you're using Mitsu Epacks. Some people make custom ME-packs. I was just checking. I'm not sure how opticam defines match lines for upper and lower profiles but make sure you have these defined at every transition. Also make sure that the operator has his Z axis settings in the machine matching the program. Otherwise, I'd potentially try the program with only 1 pass and see if it still digs with only a rough. It will give the rough pass a smaller offset which may = better. Thats about all I can think of without knowing anything of Opticam.

 

[Waakzaamheid]

Is the rest of the geometry correct? I'm only asking because if your Z values are way off when doing taper cutting you can get strange results like that. That's the first thing I'd be looking it. If the insert is mounted in it's holder, make sure your program plane value is actually to the top of the insert while it's in the holder.