[claya]

When plunging at rapid, the machine will alarm with an OC (Over current) on the Y axis. (Yes, Y-axis) It only happens at 100% rapid. And it is ALWAYS an over current on the Y-axis. Sometimes it very randomly happens when the machine is sitting idle. But is fairly repeatable when plunging. It nearly always happens at the bottom of the plunge, where the tool is just above the part. (a inertia thing?) Have talked to others and Mori Service.

Happens more frequently when motor is high RPM, it seems.

any ideas welcome. axis brake, motor dirty, drive calibration? Mori suggested a cable short.

[machinistDroid]

Had a similar sounding alarm on a mid 90's Bridgeport 3020 with a Fanuc 21m control. It also would happen, infrequently, when the machine was idle. Progressed to the point that the axis effected would alarm when using MPG. Turned out to be the axis brake locked up and put a load on the drive to cause the alarm.

[underthetire]

Since you didn't post the control type, I can only guess. Regen resistors for the drive units failing.

[claya]

Since you didn't post the control type, I can only guess. Regen resistors for the drive units failing.

Regen resistors was suggested before. It may have been you... Yasnac MX2 control. How do I check them? And which ones? The error is always on the x or y axis. Is that just where the oc occurs, even though it is the z-moving? A LOT of comments, from various sources, a while back suggested dirty or worn commutators. (DC servo) I have cleaned the x & y motors, but have not pulled the z-motor, since access is much harder. The error moves from y to x, when I swap cable pairs, so that means it is in the cable, or is that just a phantom? If it is the regens, moving the cable is just moving the OC to the other motor??

ca

[underthetire]

Regen resistors are fairly large, usually on the outside of the electrical enclosure with a metal cover over them with vent holes. When these start to fail, the braking current goes up and can spike the rest of the system. I have a hard time believing it would be a Y axis cable, you would see an alarm when Y moves. Since they are DC drives, I am thinking at this point you need to re-tune the drives, especially the balance. Unfortunately, Yasnac was somewhat uncommon out here, so I have very little to go with.

[claya]

Regen resistors are fairly large, usually on the outside of the electrical enclosure with a metal cover over them with vent holes. When these start to fail, the braking current goes up and can spike the rest of the system. I have a hard time believing it would be a Y axis cable, you would see an alarm when Y moves. Since they are DC drives, I am thinking at this point you need to re-tune the drives, especially the balance. Unfortunately, Yasnac was somewhat uncommon out here, so I have very little to go with.

How do I test the regens? I know where they are. Do they drop in resitiance over time/heat? The spike makes the most sense during motion. Every once in a while 1/200 it will oc during idle. Mori's first response was a shorted, y-axis cable, at a sheet metal edge.. Or cracked insulation/coolant short. Perhaps its a common failure for the specific machine? IDK..

Drives are tuned. I do that every year. Any idea how to find out what the over current value is set to? Measure the current?

I can nearly always force the error during a z-plunge at 6K rpm. Lower rpm is not so repeatable.