1st of all I see you video , spindle running in low speed setting 30 RMP? actual 28. 29. 27? not so clean? what about you idea ? what do you think the tolerance such as 1% or 5% you will call it stable?

2nd 810D (SINUMERIK 810D) is a CNC controller , you want to make spindle rotation (RPM) stable you need investigate into spindle drive system 

Normally spindle drive is a speed controller, 810D CCU box integrated 2 or 3 of 611D type of drives.

check your machine configuration to find what kind of spindle motor machine used and what / which is spindle drive. then making speed control loop tuning to improve stable  

There are some other factors to affect spindle stable , such as cutting speed / load , spindle speed ( high speed may easy to stable )

Hello Khairie, 

1. I guess this machine is in running condition & the problem arose. As such any parameter setting will not solve the problem & you need to troubleshoot it as suggested by expert nulizhang.

2. Which type of motor? article number?

3. Have you checked motor cable, in case encoder, encoder cable? Have you checked motor winding resistance? Is it balance? also motor I.R.? Motor cable for short circuit/ground?

4. How much current is drawn? Do you hear any abnormal sound from gear box?

5. Have you noticed DC bus link voltage? Is it stable or fluctuating?

Please check.

 Yes you did the right thing. MD1xxx calling Drive machine Data, in 810D/840D they are servered for 611D drives. in detail , as your spindle is in speed control loop

MD1407 is  Speed control Gain Kp

MD1409 is  Speed control Integer time Tn

through adjusting those 2 MD's you can make your spindle drive tuning --that will get quick response for disturbing --so your spindle will run more stable  

Thanks for sharing

Khairie

Thank you master for your feedback.

I solved the problem by adjusting values MD1407 and MD1409 at Drive MD. Now machine back to production.