Stepper motor jamming - please help

[deepeshmishra]

Dear friends
I had made a stepper motor full step drive which was started jamming after 3 month of run.
after jamming when i apply mechanical force to shaft by plier it releases and starts working fine but after 3-4 run this problem repeats.

 

[barry]

Bad bearing.

 

[ahsan_i_h]

Spray WD40 or contact cleaner at the end of the shaft. Wait for some time then check again. See the picture.

This will clear the bearing. If it does not work then you may need to take out the bearings for through check.

 

[D.A.(Tony)Stewart]

worn bearings?

 

[ZASto]

Buy yourself a new stepper, do not try to disassemble the bad one, it's a bad idea

 

[deepeshmishra]

Thanks for reply.
Dear Friends but I dont think this case is for Bad bearings I have tried Spray WD40 But problem is there.
I searched on google, and found a line "Mid range resonance " what is this mean ?

 

[barry]

Resonance has nothing to do with a shaft that has to be loosened with a pliers. What you describe sounds like a mechanical binding problem. Does the problem still occur if you disconnect the shaft from the load?

BUT if the problem is a mis-matched load, you could see a situation where you lose steps and the motor stops moving because it can't develop the required torque at high speed.

 

[deepeshmishra]

Thanks to all of you. For now i have solved the problem by changing motor and now it is working.
If the problem comes again in new motor then i will come for discussion about this topic.

 

[barry]

Thanks to all of you. For now i have solved the problem by changing motor and now it is working.
If the problem comes again in new motor then i will come for discussion about this topic.

When in doubt, throw it out.

 

[deepeshmishra]

When in doubt, throw it out.

I had made the drive using two H bridge, using bipolar stepper motors, My job was to drive motor less than 1 rpm, I did it but the motor was taking too much current. So i started choping supply of motor at 458 hz and controlled current by varing duty cycle i got good torque with speed customer required.
After 3 month this problem comes I feel that it was something magnetic jam and I replaced motor.
What you think?

 

[chuckey]

loose magnet on the rotor?
Frank

 

[D.A.(Tony)Stewart]

YOu probably had a sleeve bearing. Any warp in the shaft from an excess radial load might cause this. Any warp might cause the rotor magnets to scrape the stator.

 

[barry]

I had made the drive using two H bridge, using bipolar stepper motors, My job was to drive motor less than 1 rpm, I did it but the motor was taking too much current. So i started choping supply of motor at 458 hz and controlled current by varing duty cycle i got good torque with speed customer required.
After 3 month this problem comes I feel that it was something magnetic jam and I replaced motor.
What you think?

If the motor was "taking too much current" you could have damaged it.

 

[deepeshmishra]

If the motor was "taking too much current" you could have damaged it.

I had not run it more than 10 minute in my complete test.
Motor specification was 3 ampere 18.9 kg/cm.
I run it 4 amp to 5 amp but for test purpose not more than 30 second at a time.
So for this reason can I think My motor was damaged while my testing time.

 

[barry]

It's possible that the excessive current could have partially demagnetized the permanent magnets, but it's hard to say. But I think the fact that it ran for 3 months indicates it's probably a mechanical issue.

 

[deepeshmishra]

I agree with you "partially demagnetized the permanent magnets" can be the reason for motor damage.
But for now i have replaced it, and till now it is working, If problem comes again then I have to come into deep water.

Thank you barry for sharing this much information.