SlantTurn30ATC Alarm 2 & 218

Our ST30ATC T3 started to behave very strange in Z suddenly, it was a few mm off in diffrent direction from time to time and eventually gave Alarm 2 & 218

Alarm 2 - Servo lag excess Z axis
Alarm 218 - Axis move misoperation

My thoughts is:
1, resolver on ballscreew
2, "Thing" at the end of servomotor
3, Servo

Since I was not in place I asked the operator over the phone to loosen the resolver and carefully pull it to see if the flexible coupling was brooken and the conversation was like this:
Me - Now carefully pull the resolver out
Him - Its out...
Me - Then the flexible coupling is brooken?
Him - Yes...
Me - Was it brooken or did it break when you pull it?
Him - ...I dont know.

Anyway, I have ordered a flexible coupling and hoping that was the problem but is there anyone with experiance of a very suddenly problem like this and what was the problem?

If your servo motors are DC they have brushes. you indicated a T3 control, and all I have worked on were DC.
They can be worn out and the shunt is burning into the commutator, stuck in the brush holders and burning the comutator, the motor filled with oil or water, are common problems that seem to be the cause when the motor can't position properly. The 2 alarms you are getting indicate that the motor can't position the axis properly, the lag error means that it didn't get to the proper position.


The resolver on ball screw is probably an encoder not a resolver. The couplings break, they get water in them, and they do go bad.
The "thing" on the end of the servo motor is probably a brushless tach. I would look over the other areas before messing with it.
Yes servos give problems too.
But I would give the motor a good look over first.

Bill

on edit:
Even if the coupling "fixes" the problem, I would at least check brushes before putting it back in service.

The coupling did fix the problem
Are the brushes easy to access?

I did found some other small issues I also fixed:
-The timing belt (servomotor-ballscrew) was slack (or loose dont know what proper word to use )
-The nut holding the pulley on the ballscrew was loose
When these 2 issues was fixed I reduced my backlash from 0,17mm to 0,04mm. (Parameter BL Z reduced from 170 to 40)

benganboll said:

Are the brushes easy to access?

Click to expand...

Usually they are, they are under threaded plugs on the tach end of the motor.

Bill

benganboll said:

Are the brushes easy to access?

Click to expand...

FYI, there are 4 brushes to each servo motor.