Preventing problems before they occur is the best way to avoid downtime and failures.
by Mike Fitch, LUDECA, Inc.
June 19, 2013

To put an end to or get rid of defects, end users must first detect them. The art of detecting defects is called condition monitoring. Once detected and quantified, they can be prioritized and systematically dealt with.

Condition Monitoring with Vibration Analysis
Operators have realized the need for metrics. Metrics are measurements of any elements, actions or reactions that need to be controlled. Drivers need a speedometer to measure their speed, so they can keep it in the appropriate range to avoid the cost of a speeding ticket. In this same way, operators need constant information about the condition of their assets, so they can keep them in the most profitable range of condition.

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Figure 1. Impact report of a vibration analysis program


In process-related rotating equipment, defects that lead to process failure and downtime are so costly that technology has been created to measure their condition. In addition to the sensory observations of experienced repair and operations technicians, state-of-the-art electronic devices are available for focused defect detection. Some of the most widely used condition monitoring technologies include:

  • Vibration analysis
  • Infrared thermography
  • Ultrasonics
  • Oil analysis
  • Motor current or circuit analysis

One of the most informative technologies for monitoring rotating equipment health and condition is vibration analysis. All rotating equipment vibrates as energy is fed into it and channeled to do the work for which it is intended. Some vibrations are harmless and must be accepted as a normal operating condition. However, some are defect generated and wear equipment assets if they are allowed to continue.

Some defects that are easily detected with vibration analysis are reversible, and the failures they lead to are preventable. Some are not reversible and will lead to inevitable failure. However, knowledge of the condition allows end users to decide the timetable for removal from service and repair instead of experiencing an unexpected failure, with greater costs. In most cases, prevention and preparation are much less expensive than sudden, unexpected failure. In many industries, an effective vibration analysis program—including the technology and training—can be much less expensive than a single unanticipated failure.

Because defects are inevitable, end users must manage defects or react to their consequences. Figure 1 shows the detection of a severe unbalance in a precision rotor. In addition to equipment issues, this kind of defect can cause defects in the product manufactured by the defective machine. Without the information from vibration analysis, finding the cause of the defective product could be difficult and time consuming.

Figure 1 is a trend graph report that shows the impact of a vibration analysis program on a single machine. The graph shows high vibration at 1 times turning speed until the defect was removed. The vibration then falls well below harmful levels. The situation was monitored until the machine could be balanced, and the same technology was used for monitoring and balancing. Quality vibration analysis systems detect unbalance and double as field balancing equipment. The unbalance defect was detected and eliminated with the same portable tool.

Manufacturers in the U.S. are pressed to have the highest return on net assets in the world to compete with foreign manufacturers and other domestic manufacturers that have optimized their assets and processes. Managing enterprises can be complicated and challenging, but one simple strategy works when it is implemented. That strategy is defect elimination through condition monitoring. P&S