FANUC AC spindle drive deceleration issue

[nlh]

Hello,

The spindle drive is on a mid 80's Nakamura Slant Jr. lathe. It has a Fanuc 10T control.

The spindle has a very slow deceleration rate. Basically it will just free wheel until it gets to around 50-100rpm and then it weakly sounds like it's trying to break the motor by putting it in reverse.

Is there any way to change this? The drive is a model A06B-6044-H106. It's called an AC SPINDLE SERVO UNIT.

There are no alarms and other than this, everything else appears to work as it should. I should note that this machine hasn't been in our shop for very long so past history is out of the question. We haven't even made a chip with it yet.

I have called Fanuc service but I can never get anyone besides a recording and no one ever calls me back if I leave a message.

Hoping someone here can be of help.

Thanks,
Nate

[jdeere4250]

Listen, dont be bothering Fanuc about a 25 yr old drive. They are way too busy doing real "important " things.
1. Check the PCIF fuses , ( not the power fuses, not the glass fuses )
2. check the pase fuse on the top pcb.( kinda square , clear plastic )
Then see if there is any difference.

[cncserveng]

Just a quick thought, is the spindle belt oily and slipping ?

This can cause the symptoms you describe the motor pulley can stop, the drive drops out and the spindle continues to coast to a stop. The second noise you hear is the motor brake coming on/ off at the minimum speed preset, so this is normal.

Try a new, dry belt, correctly tensioned.

[nlh]

Thanks for the suggestions guys.

I will check it out this week.

Concerning the belt, I did detect some belt noise. With the spindle running in one direction, it is smooth and quiet. In the other direction it takes on a rougher tone. I have heard this on another lathe I have, once I replaced the belt it cleared up.

Now, the PCIF fuses, where do I find these? Are they on the top board as well? If so what do they look like? Jdeere4250, you mention these aren't the power fuses or clear glass fuses so I'm not sure how to identify them.

Thanks again,
Nate

[cncserveng]

can you post the error you get and the led's status on the drive when in fault ?

[nlh]

cncserveng,

When the spindle freewheels it doesn't alarm out, at least not on the screen. I have not checked the LED's on the drive yet but would think if an error was being caused it would show up. Machine runs fine other than very slow decel.

Thanks

[cncserveng]

Another little trick you can try is to program S0 M5 instead of M5 on its own, this will make the drive ramp down in a more controlled way.

Post what happens and any alarms.

Go to the servo pages and check the spindle drive current; when doing an M5 stop, an S0 M5 and an NC reset. All three should make for a different result. It would be useful to know if there is any difference in stopping time for each case.