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A different wire problem on Mits

tvalenzuela1432

Aluminum
Joined
Oct 19, 2015
Location
Ontario, California
Hello, I searched my problem on the forum and didn't find anything so sorry if it had already been covered before and I missed it. I have a problem with my wire breaking and snapping back. I can thread it no problem. Then when I push wire feed, after about 10-20 seconds, it snaps. It seems to break in the back but not necessarily where the prob is. I found it strange that even after it breaks the rollers in back still keep spinning.

What I have checked:
I cleaned both of the upper head rollers and bearings, cleaned the lower head roller and replaced thee bearings, (the spacer piece is a little messed up but even after removal and try run it still did it), took off and replaced with some old pair of collection rollers with new bearings and cleaned, cleaned aspirator, cleaned and even tried a different wire cutter, I changed spools of wire, cleaned wire guides, checked tension on screen(was 12 and went to 8) no difference.

The upper rollers do have a bit of a groove in them but I don't think that would do this but I could be wrong. I have a spare for one of them so I will change it out and try again. But that is the last idea I can come up with.
* Note: There is no spark even going to the wire as I am just trying to feed the wire and it breaks.* Mits tech was just out a few weeks ago and went through everything and it was fine then. UuGGG

Any ideas welcome :willy_nilly:

Tvalen1432
 
Hi Toni:
Does your machine have a powder clutch to create the wire tension?
I had the same problem on my old Sodick A320 and I ended up having to replace the powder clutch because the guts had partially frozen together so the clutch was no longer responding properly to changes in input voltage and always put full tension onto the wire no matter what I set the tension to on the control.

On my machine you could run the wire feed, turn the tension right down, and just grab the powder clutch roller to see if you could make it slip.
I couldn't and that's how I knew it was hooped.
If you try this, be very careful not to snag a finger between the roller and the wire...you'll give yourself one helluva cut if you do.

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining
 
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Do you have a tension meter? If yes, the tension should be 1200grammes at WT8 and 1800 at 11, if it's an analogue meter check if there is any "bouncing" of the needle, this indicates slipping. Don't forget the tension is not applied directly you turn on the wire, it is applied after 3-5 seconds. What machine is it? FA, FX etc.
 
To update and answer the questions: 1) I honestly don't know if I have a powder clutch on my FX20K or not. 2) I don't have a tension meter unfortunately to test it.
What I have found so far on machine that is a little out of the norm I will say:
A) There is a little spacer I will call it between the two bearings in the lower roller that has been a bit dinged up thanks to prior workers assembly ways I guess. I thought could have contributed to it but I removed it and still had same thing.
B) Ever since I have worked here the wire cutter holder was always cracked and we have a penny between it and the adjacent plastic that guides the aspirator part. (laugh if you must) But we have never had an issue with it before. Until I remembered the penny fell out recently about the time this started. When I put it back it must have not been exactly the same place therefore causing the cutter to grab wire or backing up wire so rollers would tend to grab. IDK.
When there was a change over to new wire cutter with blade replacements they changed the case too. Trying to get that housing part number # now.
In the mean time, I plan to run the machine without the chopper. I will have to make a few rig it changes but my concern is that I will have to be mindful to make sure the coil wire doesn't touch any metal also That I don't touch it while power is on the wire of course . Is there any thing else I should know about or that I may encounter with this change?

I hope at least with all my posts that mostly seem to be due to either "cutting costs" or "un-experienced operators" that it helps some one not to have the same issues. Because it's been pretty embarrassing at times admitting it in the end of it all. LOL

Thanks,
Tvalen1432
 
Hi Toni,

Do the following, please take out the collection rollers and clean the shaft, then place a clock in the motor shaft in order to see if it is concentric. It should be no jump more than 0.01 mm.

If there's a big jump as 0.03 or more the shaft is not OK so it means that in some moment the rollers make more pressure and is not balanced, then the wire snaps having a decompensation between main tension roller and the collection rollers.

Best Regards.
 
Mits Tech,
I'm sorry but what do you mean to put a clock in the motor shaft. Can you explain more? or differently.
Also it's a FX10 Mits machine and I don't have a tension meter. There is no bounce in the wire. I got it to at least let me align the wire and then it broke again while setting center of part.:angry: Could one of the tension wheels cause this at all? possibly pinching it while turning? All it does is provide travel direction and tension and is free spinning. I ask because it makes a tapping sound when turning. I will check the bearings in it. (Long shot).

Thanks,
TValen
 
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Mits Tech,
I'm sorry but what do you mean to put a clock in the motor shaft. Can you explain more? or differently.
Also it's a FX10 Mits machine and I don't have a tension meter. There is no bounce in the wire. I got it to at least let me align the wire and then it broke again while setting center of part.:angry: Could one of the tension wheels cause this at all? possibly pinching it while turning? All it does is provide travel direction and tension and is free spinning. I ask because it makes a tapping sound when turning. I will check the bearings in it. (Long shot).

Thanks,
TValen

I think that he means "Put an indicator on it to check concentric rotation"
 
What kind of guides does it have?

I used a Makino with PICO guides and I'm not familiar with anything else.

You would not think about it, but there is a part you should replace if it is a PICO.


The water jet nozzle on the makino plugged up, it had so much contamination / build up it was screwing with everything.

The poweder clutch wears out.

Rollers do wear out.

Find and purchase a good mechanical tension meter..
 
Sounds like bad bearings in the draw off rollers in the back of the machine. Does the wire look crimped? When is the last time you replaced them? I have replaced all the bearings before I found the right "bad" one.
 
If those collection rollers are anything more than a slip fit onto the shaft, the shaft is likely worn out.
Mitsu_Tech_Spain advice is where I would look first.

A groove in the roller is no good either.
 








 
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