[Jonathan-Naaman]

Hi there,

My name is Jonathan Naaman and I have an old CNC running on 3 phases 200V made by: Yaskawa Model: UAASKB-08CZ1. It is controlled by: VFD, made by Yaskawa. Model: CIMR-MT3-7.5K

About a week ago the VFD worn out and was sent for repair. I was advised to check the spindle motor for resistance between the body and the coils. Checking the coils, I found out that the resistance is too low.

I sent the motor for cleaning and re-coating the coils. After assembling all parts and running the machine, the spindle runs clock-wise and counter clock-wise alternately. The motor and the encoder were tested today and found to be working well.

Help,...
May anyone have any experience with such a problem? Or have any idea what may cause such a problem?

I have tried unsuccessfully to upload a short video which I may send by email.

I will appreciate any help very much
Thank you
Jonathan

[Al_The_Man]

Test the motor on 3 phase direct with the voltage stated on the plate.
Al.

[Jonathan-Naaman]

Test the motor on 3 phase direct with the voltage stated on the plate.
Al.

Hi Al,
I already tested the motor and all parameters seem to be fine.
I am convinced the problem should be in another place.
The question is where? Do you have any idea?
Many thanks anyway
Jonathan

[Al_The_Man]

If the encoder or rpm control sensor is the dual prox sensor off of a toothed wheel, it could be the differential alignment of the pulses, this occurs on older Mitsubishi spindle drives.
Al.

[SocalPE]

Jonathan Naaman,

I've had this problem before with a different machine. When I would try to run the spindle it almost seem like it didn't really know what to do... spin one way... then suddenly the other, then eventually alarm out. It ended up being that the parameters in the VFD somehow became corrupted. I did a factory reset to the VFD and adjusted the parameters as needed and have been good ever since.

[Jonathan-Naaman]

HI Al
The encoder is detected by a magnetic encoder containing a magnetic disk[

see photo

Attachment 328016

Attachment 328018

[Jonathan-Naaman]

Hi there,

Thanks for sharing your problem with me.

The way you describe the problem is exactly what happened to me

I will check your advice and let you know if it worked out for me.

I will try to insert a short video showing the problem.

Thank you again
https://youtu.be/ymy72y_a8BA