Fundamentals of vibration analysis

In any machine, the amount of vibration depends on a number of factors — the exciting force, the closeness of frequency of these exciting forces to structural resonances or their multiples (harmonics), and the restraints the machine structure imposes to vibration. Vibration analysis is a non-intrusive, fast response, preventative maintenance solution that measures the vibration characteristics in rotating equipment based on three main parameters — velocity, displacement and acceleration.

As part of a predictive maintenance strategy, vibration analysis can prove crucial to predicting breakage, planning appropriate repair and substituting damaged parts before disaster strikes.

 

How does it work?

An accelerometer is used to collect vibration readings which are analysed by software systems to detect anomalies with the machine. Its sensors are connected to the vibrating structure and read the incoming electrical voltage generated by the piezoelectric crystal. The analysis can be conducted on either the time waveforms (amplitude versus time) or on the frequency spectrum (amplitude versus frequency) by applying a Fourier transform on the time waveforms or on both.

A complex machine has many components, each generating its own vibration. Critical components like bearings, impellers and shafts in large rotating equipment require a more in-depth evaluation. In this case, a spectrum analysis is better to get a clearer picture of the vibration frequency.

The data collected using either of these methods is then recorded using a vibration transducer at various points around an electric motor, pump or generator. A qualified engineer will then analyse the findings, flag issues and recommend actions to prevent breakdown.

 

Why is it needed?

Vibration analysis yields massive benefits for equipment owners, helping them spot issues early on and plan repairs, while minimising costs and reducing downtime. Acceptable operational vibration is pre-defined either through long-term utilisation, maintenance history or through standards established by the OEM. If this limit is breached, there is an indication of a potential defect or health problem.

Furthermore, vibration analysis supports remote condition monitoring, as it can be performed while the system is running. If a fault is observed on one of the components, repairs can be scheduled in advance during non-productive times to avoid costly downtime.

New developments in automated accelerators and artificial intelligence-equipped sensors allow even non-specialist users to work with vibration analysis. When the vibration level of an equipment is exceeded, the owner receives message alerts.

However, an experienced analyst or technician is still needed for making sense of the findings and suggest the best course of action. While most vibration analysis systems can provide a good level of data analysis, an experienced engineer can provide a more informed interpretation of the readings and advise machine owners on the necessary steps.

At Houghton International, we use our expertise to plan a suitable analysis schedule, depending on the criticality of the application. Following the vibration analysis, we suggest the best course of action, which could range from balancing the equipment on site, replacing bearings or the complete removal of the unit from site for repair and overhaul in our fully equipped workshop.

As vibration analysis brings a great deal of benefits to engineers, from real-time reaction to reduced downtime and increased operational safety, it is important that they make the most of it by working with a specialised technician.

 

Find out more about our vibration analysis services at www.houghton-international.com .

 

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