Rotor Balancing Expert Tip

Guest Post by Bob Dunn from I&E Central, Inc.
A customer was having difficulty balancing the rotor shown above. They had made multiple corrections, some contradictory, and were worse than when they started. In that this is on a shop stand and controlled conditions, something was not right. Looking at the photo, I saw a couple of likely issues.

  1. The shaft is pretty reflective itself, it is doubtful that they were getting a good or consistent phase reading. I recommended they put a ring of black tape on the shaft, with the reflective tape on the black.
  2. The tach sensor is pointing at the shaft at about a 90 degree angle. Optical sensors and reflective tape works better if the sensor is aimed at an angle – 30 degrees or so.
  3. The tach sensor is pretty close to the rotor. In this case it is not too close, but you can be too close. A sensor like this will work from several feet away, if you are having problems, try moving the speed sensor further away.

The customer applied the tape and adjusted the tach position. The rotor was balanced in a single run.

by Yolanda Lopez

How to Balance Rigid Rotors

If you want to find the secrets of the universe,  think in terms of energy,  frequency and vibration.” ? Nikola Tesla

Could Tesla’s secret be the energy wasted due to vibration at a frequency equal to shaft speed all caused by rotor unbalance?
Balanced rotors are critical for achieving production and profit goals. Unbalance creates high vibration, which leads to other faults resulting in decreased machine life, wasted energy and reduced efficiency. Smooth-running machines are required for producing products that meet customer specifications. The IOSR Journal of Mechanical and Civil Engineering states that rotor unbalance is the major cause of vibration problems. A good balancing process is essential for successful physical asset management.
Read my entire article Field Balancing Rigid Rotors at Reliable Plant.

by Bill Hillman CMRP