wire EDM taper issues after a PM schedule

[spanish_john]

I've been running an MV-R1200 and MV-R2400 for the past year with no issues on my part but 2 months ago we had a PM schedule done on both machines and after they were done the machines started moving on the U and V axis even while doing straight cuts. One machine moves within .00012-.00029" while the other machine moves .00086-.00202" in the U and V axis using the same program. We have made multiple different programs with linear movements as well as arcs and it stays consistent between them. We compared the programs we ran before the PM schedule to the ones we are currently running and ruled out post-processor issues. The U and V movements only occur on the contour passes, if I program a part to pocket and then contour, the pocketing portion has no U and V movement. We run our parts using only 3 contour passes and watching it run we noticed that the first pass which runs clockwise has the largest value, then the second and third passes run the same lower value.

 

[ranchak]

I had a PM done on my MV-1200S two and a half weeks ago. Since then the machine will not consistently thread. I would call Mitsubishi and let them know about your issue. I'm waiting for a tech to be free to come out and fix whatever got put back together or aligned wrong

 

[spanish_john]

We called Mitsubishi and they led us down a rabbit hole of different numbers to call, then once we got someone out here he didn’t know what he was doing couldn’t even level the machine properly. There’s something that either they changed or didn’t turn off when the did the PM because we checked all possibilities when it comes to programming and everything we’ve done is correct. We’ve even tried pocketing and contouring holes of different sizes as well as a hexagon in different corners of the table and the movement on the U and V was consistent on everyone of them.

 

[JZ.]

I've been running an MV-R1200 and MV-R2400 for the past year with no issues on my part but 2 months ago we had a PM schedule done on both machines and after they were done the machines started moving on the U and V axis even while doing straight cuts. One machine moves within .00012-.00029" while the other machine moves .00086-.00202" in the U and V axis using the same program. We have made multiple different programs with linear movements as well as arcs and it stays consistent between them. We compared the programs we ran before the PM schedule to the ones we are currently running and ruled out post-processor issues. The U and V movements only occur on the contour passes, if I program a part to pocket and then contour, the pocketing portion has no U and V movement. We run our parts using only 3 contour passes and watching it run we noticed that the first pass which runs clockwise has the largest value, then the second and third passes run the same lower value.

How do the parts measure? Do they have taper that you don't want or are they straight?

Was there a software update? A lot of machines now will move the UV while cutting to comp with the burn to keep the cut straight.

Have you tried re-booting the machines? Some parameters/settings may not turn ON and OFF until it is powered down and fired back up.

I am not familiar with Mitsubishi Wires just some thoughts from my experience, hope you get it figured out.

 

[Waakzaamheid]

I was going to say what JZ said. On the newer Fanucs I've worked with, some of the newer technology will automatically tip the U and V to get a straighter cut. If you've been only talking to service guys, I would recommend giving applications a call and see if this is something the Mits does.

Edit: Second post in this thread mentions the straightness compensation- https://www.practicalmachinist.com/forum/threads/wall-straightness-question-on-mv1200s.368458/

I would bet that's what's happening.

 

[spanish_john]

When the PM was done they did not update the software. When we finally got a tech out to take a look at it, he updated one of the machines while doing the maintenance on it and we ran test one both machines to compare. The week prior when we tested that machine we were getting U and V movements between 0.00012-0.00009” but after the update the movements became 0.00203-0.00086”. The list of test that we ran programmed using only straight cuts are as follows; grinding the OD of a cylinder as well as both faces square and parallel then pocketing and contouring a .25” hole on center, grinding a block square and cutting out a die with .75” dia OD and a .25” dia ID, cutting multiple dies using the same program but rotating the program 90 degrees each time. Once we ran those test we check for squareness to the faces as well as put them between centers on a granite plate and we checked run out and Concentricity and we found a repeating pattern on both machines skewing the cut towards -X,-Y no matter the orientation of the program or location of the part on the table. We’ve measured over a 2” distance a .004-.007” taper. Prior to the PM schedule we had 2 months ago we had absolutely no issue like this.

 

[JZ.]

When the PM was done they did not update the software. When we finally got a tech out to take a look at it, he updated one of the machines while doing the maintenance on it and we ran test one both machines to compare. The week prior when we tested that machine we were getting U and V movements between 0.00012-0.00009” but after the update the movements became 0.00203-0.00086”. The list of test that we ran programmed using only straight cuts are as follows; grinding the OD of a cylinder as well as both faces square and parallel then pocketing and contouring a .25” hole on center, grinding a block square and cutting out a die with .75” dia OD and a .25” dia ID, cutting multiple dies using the same program but rotating the program 90 degrees each time. Once we ran those test we check for squareness to the faces as well as put them between centers on a granite plate and we checked run out and Concentricity and we found a repeating pattern on both machines skewing the cut towards -X,-Y no matter the orientation of the program or location of the part on the table. We’ve measured over a 2” distance a .004-.007” taper. Prior to the PM schedule we had 2 months ago we had absolutely no issue like this.

That is some excessive taper over 2in. At least you were able to prove out there is definitely an issue, hope they can get it running good again for you.

 

[spanish_john]

I really hope so. Do you have any suggestion of parameters we can look at that could possible turn off any type of compensation.

 

[plastikdreams]

Wow that's an interesting issue you have. I can't think of anything on a mits machine that would make the u/v move when not commanded.

Are you sure no strange button is illuminated on the screens? Like axis rotation or something.

 

[Jim7511]

Maintenance Tab > Switches button > Straightness CMP

Make sure that box is NOT checked.

Updating the machine reset a lot of little things that get turned off/on

 

[modelmakerblue]

I used a Fanuc wire edm not a Mitsubishi but if your U & V axis is actually moving something must be telling them to move & that something has got to be connected to the PM. As said parameter, settings or some such?

 

[tvalen1432]

Straight Comp is the only setting I am aware of that will do that in the settings. I was told though that it wont work unless you have a G41 or G42 in program. Do a test piece and try taking that out of program as well as using an off set of H1=.0000. See if you still have that taper. If it still the same at least you can rule that out for straight comp being reason.
Tvalen1432

 

[tvalen1432]

See if happens in the "Optimum" setting or if you turn PM off.