A month ago, one of three major production lines started shaking. The problem has gotten worse, and now your boss wants you to solve this problem. You look in the CMMS and find that the main drive motor has been aligned three times. There was no "as found" or "as left" alignment or vibration data, just an entry stating it was aligned.

How can you efficiently solve this?

First, take vibration readings at the motor with the load coupled to it (for “as found”). Then, uncouple the load and take vibration readings. If these are unacceptable, check the motor's:

  • Pedestal for cracks or distortions.
  • Base for warpage.
  • Feet for warpage (improper bolt torque is the cause).
Also:
  • Test the motor shaft for runout, using a dial indicator. If runout is excessive, then replace the motor or send it out for repair.
  • Check the branch/feeder with a power analyzer. Address any significant power quality issues.
After completing these steps, laser-align the motor. If the earlier readings were acceptable, the problem isn't at the motor. Therefore, check the:
  • Drive belt (if it has one) for alignment, integrity, and tension. Note: Wrong lubricant/dressing on the belt can result in vibration.
  • Gearbox (if it has one) for alignment and lubrication.
If the motor and coupling aren't causing the vibration, the problem is in the line itself. Just as you checked the motor pedestal, base, and mounting, you now need to check each provision of the same on this line.

If you still have vibration after doing the above, unbolt the line at about its halfway point and mechanically isolate the two halves. If the vibration disappears, then its source is in the second half. Rejoin the line and split it again halfway between the halfway point and the end. If it does not disappear, go the other direction with a halfway split.