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Help w/Fanuc Built-in Spindle Motor Failure Modes

13engines

Stainless
Joined
Jun 30, 2015
Location
Saint Paul, MN
Greetings All,

Trying to aid my decision process about pulling my spindle out for inspection/repair.

Particulars:

1997 Mori Seiki SV-50/40 Fanuc 18MC
Fanuc Built in Spindle Model: Alpha B132L-18.5
Type: A06B-1241-B610#N941
20HP Cont./ 25HP 30 min - 124A Max

Useful information:

Spindle has thru the flange HP coolant.
Also has air/oil bearing lube and a positive air pressure system to aid in keeping bad things out. (This may be my problem)

See attached drawings for section view. NOT - couldn't get them small enough that PM would allow upload.

My spindle is making noise. Especially at initial startup, and off and on during job running. The thing is, it doesn't seem so much like bearing noise (high pitched vibration/rattle/ball skating/vibration changing with speed/squeal) but more tonal like a note played, especially one created by air, or something spinning in a space with free (possibly coolant contaminated) area around it. If any of you have ever run a Mori Built In Spindle without a tool shank mounted, you'll know the air-motor-ish sound they make while spinning. This sound I'm worried about is like that but slightly different in a way I'm somewhat at a loss to explain.

I have a startup program that runs the spindle and moves the XY axis in a figure 8. The Z axis moves up and down in a cycle that matches the speed of a complete once around of the figure 8. With the spindle starting at 2500 RPM, the sounds starts immediately while the Z axis satisfies the first block of the program with about a Z-6.0 move. Many times at that brief pause before the next block the sound will vanish or got much less. It may come back again though at some point. I can climb away from the sound at higher RPM, but I'm not sure if this is just reaching out of my less-then-best hearing range or what. I can feel vibration on the upper spindle housing sheet metal, but really nothing with my hand on the spindle housing proper down by the spindle/tool interface. The sound is much worse if the machine has sat for a week or two. It also seems worse if I run the startup program with a heavy tool in lieu of a light one.

So my question(s)

Does anyone have experience with the failure modes of these built in thru coolant spindles? There are a lot of O-rings involved in them that's for sure. I've heard that coolant can get down into them. Are there places that aren't specifically bearing places that can collect coolant and possibly make noise when things start spinning? Can a bearing partially filled with coolant get tonal instead of metallic sounding at first start up? There is a bit of coolant sitting on top of the motor right now.

I haven't really seen any finish problems in the work coming off the machine. The machine was recently rebuilt from the ground up with everything important replaced new. The only thing that wasn't touched was the spindle. Though when I bought it, the spindle had been replaced not so many years ago. Awhile back I lifted a steel part out of a vise with a 3" face mill. It trashed 4 of 6 pockets. The machine killed the spindle immediately. I believe this sound existed to some degree before this happened. It does seem to be getting slowly worse as time and thru spindle coolant use add up.

Anyway... again. Failure modes anybody? Ideas?

Finally - if it comes to this. Looking at the drawing, it seems I can drop the entire spindle from top to bottom wires and all (after backing off 4 set type screws coming in from the sides that are super hard to see in the drawings) just by unbolting the bottom flange from the Z axis casting. Anyone have experience removing one of these built ins? Mori or otherwise? Any tips on how I can lie to the computer so I can move the Z axis and others with the spindle disconnected?

Sorry about the bomber length post. Thanks for listening.

Dave
 
Dave I'd let this soak a bit and see if anything comes of it. If not copy and paste this into a new thread on the NC board. I think you'll have some luck over there.

Brent
 








 
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