Troubleshooting Vibration Problems

Periodic vibration measurements are commonly used to monitor machinery condition. Increasing vibration levels or changing vibration signatures are a sign of a potential problem. The problem may be a simple as a loose bolt, or it may be more complicated.

Armed with a series of vibration measurements, you can determine if changes are happening. However, it can be very difficult to truly understand the measurements. That is where ODS and impact response measurements can be of tremendous benefit. For example:

• Baseline vibration shapes (animations) can be generated with the equipment in good condition. Periodically, the machine can be re-analyzed to determine if the shape of the vibration has changed. In some cases, vibration characteristics may change significantly, without an increase in the overall vibration levels.
• Vibration measurements can be taken on both sides of a bolted joint. The ODS animation can quickly and clearly show whether or not the joint is slipping. If so, the problem can be fixed before it leads to a more serious failure.
• When supports are modified, or repairs are made, ODS measurements give a clear picture of the effectiveness of the modifications.
• Vibration measurements can be taken on a machine base and the foundation. The animated vibration can show if the structure has broken loose from the supports.
• If high vibration levels are found, impact response measurements can identify the presence of mechanical resonances and corresponding modeshapes, to see if mechanical resonance is contributing to the problem.
• ODS measurements provide a very effective tool for communicating vibration results with others.

Effective Communication

As the last item above mentioned, sometimes the hardest job is communicating the nature of a problem (with supervisors, co-workers, contractors, etc.). When describing a vibration problem, a clear picture of the motion can often show the nature of a problem in a few seconds, while showing them a vibration spectrum might provide very little insight. When everyone understands a problem, it is easier to work together to develop an effective fix.