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Fanuc spindle drive contactor failure and replacement.

kineticmx

Aluminum
Joined
Mar 10, 2014
Location
United States, CT
Hi folks,
My Nakamura with a Fanuc 11T has had some spindle drive issues in the past.
Spindle Drive: A06B-6044-H108 Series 8
I replaced the MCC contactor about a year ago, and it just failed again today.
It happens right on startup, after the machine had sat for a week and a half.
Its a 200-220v coil that has burnt out on both of them and they are stuck in the open position when I replace them.
The Contactor is a 15kw FUJI FMC-4

I bought some used ones on ebay and a "refurb" from radwell but its discontinued. So ill be sitting on a bunch of the coils incase it happens again.

Being physically stuck in the open position the coil must energize and cook itself until it shorts, blows the fuse and the whole drive goes dead.
What would cause the contactor to stick in the open position besides the filth covering everything in the cabinet of a dirty 40 year old machine. I guess if I let it sit in the future ill go manually actuate it a few times before startup. Lubrication?
 

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So far when I found the same issue its because the coil can't pull the contacts in fully and the amp draw skyrockets , hence coil burns out.
Contactor must snap right-now.......
Could be that series of contactor is just that way....
Literally bugs getting in there, doesn't allow contacts to close...
Doubt you are covering the contactor with that much dirt/oil/grime .....maybe???
 
This lathe had a hard life and there is coolant residue everywhere in the cabinet from missing air filters. The spindle drive is GOOEY.

When I pulled both contactors they took something like 10+ lbs of pressing on the contactor button to pop them loose from the open position. As Im explaining it Im now understanding what has happened. The coolant residue is gluing the switch open and if I let it sit for a week + it sets up and theres my issue. Especially as the shop gets colder here in new england.

Soak contactor in denatured alcohol to purge the sticky stuff?
IMG_1685.jpeg
 
This lathe had a hard life and there is coolant residue everywhere in the cabinet from missing air filters. The spindle drive is GOOEY.

When I pulled both contactors they took something like 10+ lbs of pressing on the contactor button to pop them loose from the open position. As Im explaining it Im now understanding what has happened. The coolant residue is gluing the switch open and if I let it sit for a week + it sets up and theres my issue. Especially as the shop gets colder here in new england.

Soak contactor in denatured alcohol to purge the sticky stuff?
View attachment 416249
I don't think an alcohol soak would be bad, but I'm no electrical wizard.

Some inspection with a meter to insure there's no errant current paths would make me feel much better.
 
I don't think an alcohol soak would be bad, but I'm no electrical wizard.

Some inspection with a meter to insure there's no errant current paths would make me feel much better.
Fanuc advises alcohol (anhydrous) for board cleaning. I have found some coolant goo is alcohol resistant, but warm water will dissolve it. In those cases I have used water sparingly with a thorough blow off and drying before re-installing.
 
yep, been there, old nasty coolant gums up everything and causes problems from fans on the drives to anything that moves.
contactor must be seeing coolant spraying in that cabinet and without a filter to prevent that.
replace with any contactor that meets the amp and voltage requirements. pretty common parts.
cleaning is usually isopropyl alcohol, or other electrical spray cleaners, mostly from MG chemicals. I found with coolant, that straight water works well, but you need to make sure its 1000% dry afterwards.
 
Update:
Pulled the contactor apart, cleaned with hot water and some dawn dish soap.
A good friend/mentor of mine had a roll of 30AWG magnet wire and we rewound the coil last night.
2300 turns counted with a Starrett mechanical turn counter. That was fun.
Reassembled the drive this morning and running today, setting up a hot job right now.
You can actually see where the contactor had gotten glued together on the flat faces.

Hopefully that's the last time I have to service this spindle drive before I get a newer machine. Or maybe ill keep it forever and the contactors I ordered will come in handy one day.

By any means necessary

Ted
 

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Nice work!

I've come to really appreciate the reparability of the older machines. Late 80's Fanuc is kind of the ultimate. You can buy anything they need and the info is out there freely to fix whatever ails it.
 
Nice work!

I've come to really appreciate the reparability of the older machines. Late 80's Fanuc is kind of the ultimate. You can buy anything they need and the info is out there freely to fix whatever ails it.
Do you have any good reference material for these older generation fanuc machines? Most people say steer clear of the yellow cap machines but these girls just chug along. I struggle to find info and guidance on addressing alarms and faults, so its great until it isn't. Guess that's any quality machine though. I'm 25 and feel like I missed a lot of years in industry where these machines had good support, its all legacy knowledge now that I struggle to scrounge up, especially working on my own.

i also have a Nak Slant Jr., the little sister to this machine. It consistently has a spindle issue unless I run it at 25% rapids. Why? no F'in clue, I've no idea where to begin troubleshooting. Spindle always runs in FWD but if you try to run it at 100% rapid and make switches to reverse in a program it always breaks. I say breaks because it just stops motion, no alarm, no spindle fault, it just comes to a halt, apparently waiting on a spindle motion command. That seems like a MTB ladder fault but where do I learn enough to diagnose that issue? if the spindle drive was getting a signal it would either work of alarm out.
 
Do you have any good reference material for these older generation fanuc machines? Most people say steer clear of the yellow cap machines but these girls just chug along. I struggle to find info and guidance on addressing alarms and faults, so its great until it isn't. Guess that's any quality machine though. I'm 25 and feel like I missed a lot of years in industry where these machines had good support, its all legacy knowledge now that I struggle to scrounge up, especially working on my own.

i also have a Nak Slant Jr., the little sister to this machine. It consistently has a spindle issue unless I run it at 25% rapids. Why? no F'in clue, I've no idea where to begin troubleshooting. Spindle always runs in FWD but if you try to run it at 100% rapid and make switches to reverse in a program it always breaks. I say breaks because it just stops motion, no alarm, no spindle fault, it just comes to a halt, apparently waiting on a spindle motion command. That seems like a MTB ladder fault but where do I learn enough to diagnose that issue? if the spindle drive was getting a signal it would either work of alarm out.

Did you try to M5 / G4 X1. the spindle before M4?

You are 25 and have had a PM account for nigh-on 10 years now?



-----------------

Think Snow Eh!
Ox
 
Did you try to M5 / G4 X1. the spindle before M4?

You are 25 and have had a PM account for nigh-on 10 years now?



-----------------

Think Snow Eh!
Ox
Yep- I started slinging parts out of my high school machine shop, business registered with the state in 2017, full time on my own since I graduated college in 2020. Job market wasn't too hot in may of 2020, so no better opportunity to go for it full time.

Funny, only semester I ever made deans list was spring 2020 when we were doing all our class work from home; aka I was running parts in the shop.
Also funny, besides some 40-50 hour weeks of employment at a shop back in high school, I've never worked a full time job for an entire year.
Been meaning to start a shop thread to show how everything has progressed.

I'll try the M5 / G4 next time it acts up. I do believe I have tried to put M5 in between most direction changes.
 
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