Wire EDM - - "Bouncing Arm" ???

Hi guys, I got a problem here I can't seem to figure out. I have a Charmilles 310 machine and the "arm" is bouncing like crazy , I have changed the brake belt, changed the rollers in the lower head, put a new carbide contact in, and here is the kicker, it ONLY HAPPENS when the power is being put through the wire ! ??? When the wire is feeding by itself with no power on the arm does not bounce at all !!! Please help !


Marty

Marty,
Trying to figure out exactly what you mean... Does this happen only with high pressure flushing on? Could the flushing nozzle possibly be set too close to the bottom of the work piece? That can cause some pretty extreme vibration. If that's not it, can you give us a little more specific description of your situation?

Check the bottom contact rollers, make sure they are running true and have the proper tension. Do this with the brake on. When were your bearings changed last? Check the top contact to make sure there is no grove. If it is only when you are cutting it has to be the top contact. Have the wire running freely then turn on the brake, if nothing happens turn on the contact, this will pull in the top contact against the wire. It sounds like top contact to me. Also try a different roll of wire. If you are using a big roll on the back, put a small roll on the front.

Remove your lower head, take it apart and check The UNIGEAR. If you need the instructions, get Charmilles to fax or email them to you, it is FYI-72A. I WOuld be willing to bet the UNIGEAR is worn down to a nub. I believe the part number is 130003232 and is about $115.00. I had the exact same symptoms you did on my 310 And 510. GOOD LUCK....BTW, While you are at it you should probrably just order the rebuild kit with all new seals and bearings if it has not been done in awhile. It is not cheap, but it beats takeing the head apart again three months later because one of the bearings went bad...

BTW, The Unigear does NOT come with the rebuild kit...It is a separate charge...
Hope this helps...

Yes check the gears, I forgot about that. I have had troubles there before. Has anyone tried to wire cut stainless steel gears for there? To replace all 5 gears is very expensive.

Are you sure it is happening when the power is on and not just when the brake is turned on?

Thanks guys for the input, I was incorrect in my statement that "it only comes on when I put the power to it".

Jay Cee you were right, the problem happens when the brake is turned on and the arm starts to bounce.

Any thoughts guys ?

Thanks in advance, Marty

Yes, remove the Lower head and take ALL the gears and bearings out and inspect them for wear...which involves removeing the visible gears AND removing the guts to get to the other gears and bearings buried inside the head underneath the visible parts.

I only reiterate this because you have not stated that you have actually, physically removed the lower head and inspected every part...including the shaft connecting the wire evacuation motor and the lower head gears...

One more thought while I was typing...Have you checked the wire drive belt at the back of the machine? A worn belt without the proper tension will cause bounce in the wire too.

I still go back to the first solution...Rebuild the lower head and all your problem will most likely be solved...

Yes a rebuild kit runs around $2000 but how much are you losing screwing around with the machine and not to mention down time?!?! Time is money...

If you need the instructions for tearing the head apart...Charmilles can email them to you. You get free tech service with a Charmilles so use it.
1-800-282-1336

Thanks everyone for your input, I am tearing apart the lower head and have ordered the re-build kit. Should be up again by early next week.

Cheers !!

Marty

Chino,
I'm sorry I didn't get back on to you on this. I was in Chicago for training all week. Man do I hate that town...
The entire rebuild kit may be unnecessary but you'll need all the stuff eventually anyhow. Does your machine chop the wire and evacuate it out of the back of the machine or does it just crimp the wire and drop it out the bottom of the head?
If it's a true pinch roller (verses a crimping roller), it may be worn or in need of adjustment (flipped or re-tensioned). I won't elaborate further on that until I am sure you have a pinch roller and not a crimping roller.
Another area that would give you this problem is the belt that drives this roller. This could be a simple tensioning adjustment on the belt if the belts teeth have not been worn off. I would recommend adjusting your old belt rather than immediately installing the new as you will have to adjust the new in a month or so once it stretches a bit anyhow.

How did you make out? Getting the problem solved?? What was causing the problem??

It was the lower head causing the problem. The rebuild kit and lots of $$$ and we are good again.
Thank you everyone for your knowledge and help, hopefully I can repay the favor!

Marty