Robodrill High Amp Draw

Hi, first post. I have a Fanuc Robodrill 20k mill with a 16i-MB control. For the last 5 weeks, I've been getting amp readings of 15 to 39 amps on any of the 3 power legs. I was converting to 3 phase using a digital phase converter but Fanuc, after replacing the power supply decided that the electronics in the converter conflicted with the power supply, so, till that was replaced, they could not help further. So, I installed a rotary, identical to a unit being used by another local shop, with an identical machine. Still have high amps. Fanuc came back and again replaced the power supply and spindle drive, but, the high amps are present. Fanuc basicly has given up. Robodrill service has as well tried to troubleshoot to find the source of the amp draw with no luck.
This machine may register high amps as soon as the control is turned on and e-stop released. Amps may drop to normal (2.3) when the spindle is turned on, but return when reset, or M05 is commanded. I found this problem because wires were to hot to touch. The machine has yet to register a alarm. I'm wondering if anyone has ever encountered this problem. Everyone here is quite baffled.
Thanks, Ken

How is the machine grounded? Do you have a ground rod through the floor, or do you have a 4th wire ground back to the AC power source? Whichever method you use, try putting a current-clamp around that wire and see if all that current is going down the drain. Any significant current going to the chassis of the machine would indicate a short somewhere. That could be very dangerous to the operator if he were to touch the machine and another grounded device, like a drill press or anything else that plugs into the wall.

It does sound like the spindle drive has a problem somewhere. Are you saying that when you turn the spindle motor ON the current drops? I'm not sure what kind of spindle drive you have, but some of them use a lot of current when the spindle is shut off at a high speed. Dynamic braking is supposed to only draw current while the spindle is actually decellerating, and it should stop drawing current when the speed of the spindle approaches zero. Some spindle drives dump current into a set of big resistors when the contactors fall out with the spindle running. I would start looking for some malfunction in the spindle drive or in the spindle braking or orientation circuitry. Is the spindle motor holding orientation when the e-stop is released? If the spindle can be turned by hand when the current draw is high, then the orientation is not likely to be the problem. Are there any big resistors getting really hot?

Besides that spindle drive, there isn't much on the Robodrill that can draw that many amps without glowing red. Since Fanuc has already replaced the spindle drive, I would suspect that it's something mis-connected from the factory, or possibly a bad motor. Is the spindle motor getting hot when it's just sitting there?

Hope this helps.

Dan,
Thanks for replying. The machine is grounded be a 4th wire to the entrance panel. There is no current flow detected thru ground and the amp's exist at the same level with the machine isolated 100 % from any ground. This machine uses a regenative drive system. When the spindle stops, current generated is supposed to be sent back into the incoming lines. When amps are present and spindle is off, the spindle is very free to rotate. At one point we detached the 3 ac lines to the spindle (from the spindle drive module), and still measured high amps.

My first post was a generalization of the problem. I'll try to clarify.
*** Amps maybe present at machine startup
*** If amps are normal, command 10000 or less, 17 amps
*** command M05, approx 95% of the time, amps return to normal
*** Command 12000 Rpm up to 20000, spimdle pulls 2 amps
*** Command M05, amps increase back to 17

Another point is z axis motion without spindle on also results in increased amps. If I'm touching tools off to set lengths, about half way to the part, I can hear the spindle fan change pitch, check the amp meter and amps are back up. Issue a tool change, and amps are back down. I'm thinking Z axis brake but Robodrill folks don't think so.

These points are not consistant. Rpm's & amps change. There have been times where 4000 rpm will not create amps, but 3500 will. The amp level has changed as well. The hi-39 amps have not been seen since the rotary converter was put into service. Now hi amps run between 13 & 19.5. Thats good, but not correct. Have not checked spindle temp, but have searched for hot spots in back of mach with no luck. Wires are getting warm. Am mostly concerned that the hi 39 amps come back. I really think things may have gotten close to fire status when problem was first detected. Basicly, I'm not running this machine. Just not worth the risk.

Thanks again, Ken

A point to consider. If this is a new machine (or near-new), and fanuc can't find the problem, they should replace the machine. At the last place I worked we used Kira machines. We ran one of them for two years 24 hrs a day 5 to 7 days a week.
We ended up having a couple recurring problems (nothing major), Kira offered to replace the machine to keep us happy.
I would like to know if fanuc would do the same, just for future reference.

jderou,

It has been requested of fanuc to either replace or repair this machine. Fanuc has responded with a number of suggestions for repair. Because of the time of year, its going to be difficult to follow thru in a timely maner, but we are working on it.
If they will replace the machine or not remains to be seen. I'll keep you appraised as time goes by.
Thanks,
Ken

Hi Guys, I Hope Somebody Could Help Me, I Have A Robodrill T10-a
Whit A Fanuc 16ma Control.
Recently Becomes To Show The 911 4n+1 Alarm, At The Power On.
So, We Call A Mexican Fanuc Reseler, And He Comes To Check It, So After Some Testing, He Says We Must Buy The Main Cpu Board, So A Few Days Ago We Install The New Cpu Board, Whit The Old Modules (like Pcm, Ram, Control,etc) And The 911 4n+1 Alarm
Its Still Present.
So, We Have Another Robodrill In Good Shape Working, So We Took The Main Board From The Working Robodrill And Put It Into The Damage Robodrill And It Works!
Next Test Was To Change The Good Modules From The Working Main Board, Into The New Main Board And Put Into The Damage Robodrill, So....result= 911 4n+2 Alarm
In Both Tests We Reset The Memory Whit The 'delete' Key At The Power On Shutting, And Nothing Happens
Now, The Fanuc Represent Seller Can't Come Right Now, And I Have A Lot Of Job To Do, So Anybody Can Help Me?

Thanks

Quote:

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Originally Posted by Kenintrouble

jderou,

It has been requested of fanuc to either replace or repair this machine. Fanuc has responded with a number of suggestions for repair. Because of the time of year, its going to be difficult to follow thru in a timely maner, but we are working on it.
If they will replace the machine or not remains to be seen. I'll keep you appraised as time goes by.
Thanks,
Ken

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Hello we have a Chevalier 1620 with a oimf control and ours is doing the exact same thing. We have changed the drive and still no luck. Did you ever find the problem?

Hello we have a Chevalier 1620 with a oimf control and ours is doing the exact same thing. We have changed the drive and still no luck. Did you ever find the problem?

Does anyone on the forum know this guy that had the trouble? Im experiencing the same issue and fanuc cannot find the problem. I wish i could get a hold of ken...

I’m having the same problem with a Robodrill Mate. Is anyone familiar with this issue or have any news ideas on how to solve it? Thanks