Rotordynamics
BALANCE THIS! Case Histories from Difficult Balance Jobs
Paper No. 93
By Troy Feese and Phil Grazier
Presented at the 33rd Turbomachinery Symposium
Houston, Texas, September 2004
There are many good references for classical balance problems; however, specific ways of handling non-ideal conditions are rarely presented. Therefore, this tutorial focuses on six case histories, which illustrate actual problems that were encountered while trying to field balance different types of rotating machinery. Coupling lockup, thermal bows, eccentricity, looseness, and structural resonances can prevent successful balancing if not properly identified and corrected. This tutorial shows how these real world pitfalls can complicate balance procedures and provides some ways of dealing with these issues such as: indexing coupling parts, using inference fits, adding structural bracing, and acquiring vibration measurements at additional locations. This tutorial also gives a brief description of the common types of unbalance.
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