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416 X Servo Alarm

Krispee

Plastic
Joined
Oct 31, 2015
Hi.
We run a Sykes Fanuc W1 Wire Eroder, quite an old machine now but still very much used. Last night I ran a job overnight but in the morning when I looked at it the machine was showing a 416 X Servo Alarm and the job (a multi repeated job which runs about 30 in a row) had run off at an angle in the X direction. This has never happened before, either the run off or the alarm. I had to shut it off, which cleared the alarm, but when I tried to move the machine out of the way it ran very oddly in X. It sounded odd, kind of clicks but with a slight groan. I took the skirts off and there didn't seem to be any issue with the guides the machine runs on, enough grease there. Whenever I try and move X axis I get the sound and then it alarms out with the 416. One of the guys thought it might be the servo itself, maybe some slack in the coupling between the ballscrew and the servo.

I also posted this in the Wire Eroding section but thought it might get seen more in this section. Plus I did a little reading up and there were some issues with X axis servo errors in other machines having a 416 alarm.

Any ideas?

Regards.
Kris.
 
It seems to be the servo motor, that's the source of the noise. We are now shopping around for a replacement motor so if anyone has a spare Fanuc Servo motor going then I'll post the details.
Thanks.
 
A bad connection between the board and the motor encoder can do the same thing. I would check those first. On my Fanuc OT lathe the connector on the Z-axis motor worked loose and coolant got in the connector, just enough to leave it moist. I had the same alarm with axis shuddering during movement. As for motors check E-bay. I sold a few there when I scrapped out a machine for about 20% of new price and they worked fine.
 
Thanks, Dualkit, I'll do that. I have searched Ebay and some suppliers of fanuc motors, so far no joy. There are motors out there just the exact one I'm looking for.
 
What generation of Fanuc? I don't know squat about wire eroders, how many axis do you have?
 
I meant controller generation, usually it is around the bezel of the controller keyboard or CRT screen.
 
Unfortunately that information is at work with the machine. I'm at home now, we start early and finish early at the company I work. I'll have to get back to you tomorrow.
Thank you for all your help though.
 
If it is like a table on a mill the axis motors could be identical as are the settings. If that is the case you can swap the X-Y motors, cables, and likely the drives to isolate the problem. That is pretty much the same thing a $115 an hour plus tech will do. Looks like you are 5 hours ahead of us on the East coast of the USA. Fanuc is pretty much the most popular controller so you have a good chance of getting good help here.
 
@ Dualkit - Yeah, it's just after 5 in the afternoon here. The guy at work already kind of sorted the problem but will double check some things tomorrow.

@ Other Brother - I think it's all in the servo.

It does sound as if the bearing has gone in the motor, since they are kind of sealed up and complex units the only thing we can do is buy a replacement servo or get it repaired.
 
Alarm 416 is the disconnection alarm. Basically means that despite sending a move command to the servo drive the control is not seeing appropriate encoder signals in return. Bad cable, bad encoder are the most likely causes. Could be a bad board in the control but far less likely.

Is the machine equipped with scale feedback on the axis? If so, a bad scale can cause this alarm too.
 
My colleague thinks that a bearing in the servo motor has gone causing a juddering inside (you can actually hear it when you move the axis) which is transferring that into the encoder. Thus the disconnect, thus the alarm.
That's the theory.
Anyway, as mentioned before, looking for a replacement servo now or someone to repair. Unless we can find a machine going for spares. Will also look into all the suggestions tomorrow when I get back to work.
 
That juddering can be caused by a communication issue as a few of us have mentioned. I am almost certain your problem isn't mechanical. That motor would have to be ready to fall to pieces to be as bad as you say. Also a mechanical problem would most likely slowly progress unless it was caused by a crash. It would not suddenly appear and alarm the machine out. If the machine alarms out on boot up before anything is moved it is a dead give away it is an issue with electronics, not something mechanical.
 
@ Dualkit - Right, my boss made a suggestion something like that this morning. We are going to send the motor away to be checked out anyway, just to make sure, so won't be able to look into the connections etc. until it returns, or at least won't be able to check that that has worked. I guess I could re-seat them on the board in the meantime.
I'm assuming by communications you mean the cables or connections on the board side? The connections on the motor itself all look good and secure and don't look kinked or damaged.
 
I'm assuming by communications you mean the cables or connections on the board side? The connections on the motor itself all look good and secure and don't look kinked or damaged.

Yes, and just for the hell of it clean the board connections and reseat them. Same with the cable connections, use a quick drying electronic contact cleaner. The connection to the encoder is the important one. I am assuming you have red cap motors with the encoder mounted on the end of them?
 
Yes, and just for the hell of it clean the board connections and reseat them. Same with the cable connections, use a quick drying electronic contact cleaner. The connection to the encoder is the important one. I am assuming you have red cap motors with the encoder mounted on the end of them?

Yes, the encoder is red while the servo is black. Both the encoder and servo connections look in good condition. I had a quick look at the cabling running back to the cabinet from the servo and it all looks good, no kinks or damage. It's all old, obviously, but in pretty decent condition for its age.
 
Well, thought I would let you know that the company we sent the drive to found that the encoder had died; they replaced it and sent it back. It is now installed and working perfectly. It cost my boss a bundle but at least it is working. We use this machine a lot here so had to be done.
 
Thanks for posting the outcome so it could help the next guy that has a similar problem. I have run many different generations of Fanucs over 35 years and never had an encoder go out.
 
Thanks for posting the outcome so it could help the next guy that has a similar problem. I have run many different generations of Fanucs over 35 years and never had an encoder go out.

Yeah, first for me too, although the m/c is 28 years old, so statistically I guess it was bound to happen eventually...I have learned some things over the past couple of weeks so not a total bust, plus I got to do a more in depth cleaning on some parts of the m/c that haven't been cleaned for so many years.
Anyway, thanks for all your help and suggestions.
 








 
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