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Mitsubishi MV4800 False Wire Break Issue

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Plastic
Joined
Apr 15, 2021
Today I'm having an issue with our wire EDM that I haven't seen before. I disassembled the wire collection unit, reinstalled everything, and cleaned the upper and lower heads as well before this issue came about.

So to start with, the wire will currently thread and if I select to feed the wire by turning the rear rollers on via the control, no issues.

I'm having issues when I try to do an alignment or edge find anything. It is saying that the wire is broken and before alarming it seems as if the upper rollers are "stuttering" or in a bind somehow.

I think that for some reason the machine can't tell that the wire is threaded through the lower head, which is odd because I cleaned and reinstalled the power feeders + cleaned the power cable contacts. If I make the control cut the wire, it never cuts and the upper will try to start spooling up the "cut" wire while it is still threaded at the bottom.
If anyone has any ideas let me know, I'm about to double check some things.

Machine : Mitsubishi MV4800 about 7 years old
 

Jim7511

Aluminum
Joined
Dec 2, 2015
You need to take the rear rollers apart again, look for a groove from the wire in the rollers. Index or replace as needed. A groove barely enough to catch a fingernail on cause me problems.
Double check air pressure (.35MPa) and smooth motion of the arm that the upper roller air cylinder presses against. Also check that the copper sheet metal is still contacting the steel rollers under the mv4800 hood.


Double check that you have the machine set to the proper Ø wire and wire type for the cutting issue.
 

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Plastic
Joined
Apr 15, 2021
I checked all of this out and the issue is something else I haven't figured out yet unfortunately. However, you did point me to some things to replace soon.

I'll keep digging and call Mits if i have to tomorrow. If you all think of anything else let me know.

I still think that it's a contact issue somehow. I noticed that the lever holding my lower power feeder in place feels awfully loose. I may rob the copper rod from my other machine and see if the contact surface on my current one is insufficient. I can actually move the power feeder with the lever secured.
 

pr0xify

Plastic
Joined
Apr 15, 2021
For future reference, I fixed the issue by swapping the power feeder copper contact and lever from another machine. The wire wasn't being detected as threaded because the lower power feeder wasn't touching the copper contact. I had actually lost the spring a while back that goes with this and the copper peice may have worn down over time from indexing the carbide.

All is well!
 








 
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