Arrow spindle motor sounds terrible

[ZigwareCNC]

Just received an Arrow 500 with A2100 that was abused during shipping. Tool changer cover broke off, doors knocked off the rails, hard disk crashed. At first, that is all I thought was wrong but now that I have a new HDD, there is something wrong with the spindle...

If I start the spindle above 650 RPM, it sounds like it skips or has crap loose inside the motor as it comes up to speed. The spindle itself sounds fine but the motor is making the noise. I also get the noise if I change the spindle speed rapidly with the pendant override. Once at speed, it's whisper quiet.

My question, what could have gone wrong in the spindle motor?

Does anyone have a parts breakdown of it? Label says it's a 1-604-0002

Does it require special tools to disassemble or should I just send it in for repair?

Could it be the electronics?

[mike_Kilroy]

- seems like if it was bearing problem it would happen all the time.

- absolutely it could be the electronics (vfs5-240) drive: did you hear it run and accel decel BEFORE you bought it? Or did you buy it w/o running it this way?? Ie., did you buy it broke or did it definitely happen from rough handling - VERY IMPORTANT to figure this out right away or you will waste lots of time trying to narrow it down.....

- if you didnot hear it run before shipment, then it sounds more like a drive issue: sounds like an open output IGBT transistor; one way to help tell this: when you align it (right after z,y,x) does it go around slowly JERKY? If so, likely open output IGBT. I just diagnosed one for a customer like this; you can see the dead spot on the MotionLink Plus scope. Unlike the axis servos with magnets in them, the spindle has slip so the transistors are always moving and it cannot get stuck in one spot.

- are u sure it is not a belt skipping issue?

- u describe something that only happens during heavy torque output;p if you tried to machine something it sounds like the noise would come back too.

- the bearings used are expensive high speed ones that cost like $ 3-400 each so you really don't want to take it apart unless you are fairly sure you need to buy new bearings; when we take them apart we always put new bearings back in.

- there is a separately 220v powered fan inside the back of the motor and a feedback resolver inside that then the motor. it is possible if the noise is due to the shipment that something happened in the fan on the back of the motor, but since it runs separate from the motor shaft it is unlikely your noise.

[Al_The_Man]

Also check any feedback device on the motor, pulse generator etc, if this has been knocked or damaged, it can cause similar symptoms.
Al.

[ZigwareCNC]

Thanks Al and Mike...

Motion during alignment is smooth.

Doesn't visually appear that the belt is skipping.

I don't see the fan or feedback externally on the motor. There is a fan on the top of the motor pushing air through. When I first powered up the machine, the fan was stuck and burned out right away. I have removed it temporarily while diagnosing the spindle sound so it's not that fan.

I have an Arrow 500 parts machine from 95, the troubled machine is a 98 or 99. Can I swap the VFS5 from 1 to the other or are they matched to the motor? I could also swap the motor itself but it's obviously more work to pull it out.

I am not familiar with the MotionLink scope. Is that software built into the control or something I access outside the A2100 control UI?

[ZigwareCNC]

Ohh, and I forgot to mention... I had not operated the machine before shipping but it had been in production and according to the owner "it had no problems". I just have to take their word on that one.

[Rick Kight]

Have you removed the belts and run the motor to be sure it is the motor and not the spindle or the belts? Also we have had some strange belt noise that at first we thought was a bearing issue. If the belts are to loose they don't skip a tooth but the flap and make a lot of noise mainly during speed changes, if they are to tight they whine. Trash in one of the pully grooves is another sourse of wierd noises. From my experience when a spindle motor bearing start to go they make noise all the time, same with the spindle. We have 6 machines here that on 5 of them we run close to 10K spindle speed all the time (machining composites) so we have lots of experience with spindle rebuilds etc. In all the years with these Cinci's (since 94 or 95) I think we have only lost the bearings in the spindle motor 3 times, but we rebuild spindles about once a year or so due to the nasty 60% glass filled composite we run.

[ZigwareCNC]

I was hesitant to try that having heard that removing the belts could loose synchronization with the tool changer for spindle orientation during tool changes and thus require changes inside the VFS5 config...Is this really a concern or is everything driven off the c-axis align?

[Rick Kight]

Yes you can loose orientation of the spindle for tool change but if you mark a belt and the pulleys then you can put it back together in the correct orientation. We have done it this way before. The Kollemorgan is a pain to reset up. requires software etc. I think you can download what is needed from the Kollemorgan web site, its a pain to figure out the first time. We doid this a few years back.

[mike_Kilroy]

rick is right on with his comments and thoughts!

email me if you need the software and I can also walk u thru using it if need be if u r on cell phone in front of machine connected or we sometimes also go in via internet to run the software on ur laptop hookede up while u watch if u need.

that said, it does not sound like u have a vfs5 issue; if it aligns/orients smoothly then drive is likely 100% ok. check ricks things good.

if u do change drive out, the P1 orient position will need to be changed in the drive - it is never the same from one drive to the next unless you load the replacement drive with it and you did not remove belts or motor. if u do replacement motor themark pulley and belts as rick says will work fine to put back again afterwards.

I wud be hard pressed to blame the vfs5 or the inards of the motor from ur descriptions so far. check ricks stuff next.

let us know how u do.

[ZigwareCNC]

I pulled the belt this weekend and the motor is much quieter but still there is some sound. I think it is quieter only because there is no mass to cause torque on RPM changes.

We used an automotive stethoscope on it after reinstalling the belt and the sound is coming from the back of the drive motor. Very mechanical sound.

Also noticed that at about 600 RPM, you can hear a constant noise in the same area of the motor. I am fairly sure there is something either loose at the back of the motor or the rear bearing is shot.

Is it possible to remove the rear of the motor with the motor still installed in the machine? Looks like I could release the wires and remove the 4 bolts holding it down but I'm concerned it might not be that straight forward.

[mike_Kilroy]

I cannot answer if you can replace back bearing with motor on the machine, but there is a fan in the back of the motor.... if you think it might be a loose something, why not pull the fan OUT and try it? make sure it is not related to its hardware. u can run the motor for 10-15 minutes w/o the fan no problem. only other thing there is a very small 1.1: dia resolver that is prob too small to make any noise.

how much noise is too much noise?

idea: take a laptop computer and turn on its audio recorder (built into all windows OS). u probably have built in mic in laptop. run to the speed that makes the most noise and hold the laptop against the motor body - you will record the sound. then post it here for us to listen to; or just email to me if that doesnt work. you can also accel from 0 to say 8000rpm while recording held against it and let us hear that. maybe your noise is ok and normal?

the other thing a recording at a given speed allows us to do is put it thru a spectrum analyzer program and if there is a specific frequency associated with the noise, we can back calculate to see if it is related to 1x, 2x, 3x, etc, per rev and this helps us identify what might be causing it. for instance, bad bearings typically have a 2x per rev noise, etc.

PS: thank you for allowing us to quote you replacement rear bearing today.