We were discussing common faults we detect by vibration analysis in our previous post. Let us see here the general steps that we should follow for conducting an efficient vibration analysis.
Vibration analysisÂ
Vibration analysis is the process of monitoring and analyzing the vibrations of mechanical systems or structures in order to identify potential problems or improve performance. It is commonly used in industries such as aerospace, automotive, manufacturing, and power generation to ensure the safe and efficient operation of equipment.
Vibration analysis involves measuring the vibrations of a system using sensors such as accelerometers or displacement sensors, and then analyzing the data to identify patterns or anomalies. This can include measuring the amplitude, frequency, and phase of the vibrations, as well as the direction and location of the vibration source.
General steps for conducting vibration analysisÂ
There are following steps, as mentioned below, involved in vibration analysis .Â
Step 1 : Data collection
In vibration analysis, data collection is the first and most critical step. The quality and accuracy of the data collected can significantly affect the accuracy of the analysis and the conclusions drawn from it.Â
Hence, there are some important points that one needs to consider for data collection in vibration analysis.Â
Sensor placement: The vibration sensor must be placed at a strategic location on the machine to capture the relevant vibration signals. The placement of the sensor should be based on the type of machine and the specific components being analyzed.
Sampling frequency: The sampling frequency should be set to capture the highest frequency of interest. A higher sampling frequency can capture more detail in the vibration signal, but it also increases the size of the data file and processing time.
Signal averaging: To improve the signal-to-noise ratio, multiple measurements can be averaged. The number of measurements to average should be determined based on the signal-to-noise ratio and the time available for data collection.
Operating conditions: The machine should be in normal operating conditions during data collection. If the machine is not operating under normal conditions, the vibration data may not be representative of its normal behavior.
Data storage: The vibration data should be stored in a way that ensures its integrity and facilitates its processing. It is recommended to use a digital format such as ASCII or binary, and to store the data on a reliable storage medium. Â
Step -2 : Analyze the vibration data
After the vibration data has been collected, the next step in vibration analysis is to analyze the data to extract relevant information about the vibration patterns and behavior of the machine. There are some common techniques and approaches, as mentioned below, used in vibration data analysis.Â
Frequency analysis: Frequency analysis involves converting the time-domain vibration data into the frequency domain using techniques such as Fourier analysis or wavelet analysis. This allows us to identify the frequency components of the vibration signals and their amplitudes.
Time waveform analysis: Time waveform analysis involves analyzing the raw time-domain vibration data to identify changes in the amplitude and frequency content over time. This can provide insights into changes in the machine's behavior or the occurrence of specific events, such as impacts or changes in operating conditions.
Spectral analysis: Spectral analysis involves analyzing the frequency spectrum of the vibration data to identify specific frequency components and their amplitudes. This can help identify the presence of specific faults or defects in the machine, such as unbalance, misalignment, or bearing wear.
Order analysis: Order analysis involves analyzing the vibration data in terms of the machine's rotational speed or orders. This can help identify the presence of faults or defects that are related to the machine's rotational speed, such as gear wear or tooth damage.
Statistical analysis: Statistical analysis involves analyzing the vibration data to identify trends or patterns in the data over time. This can help identify changes in the machine's behavior or the occurrence of specific events, such as wear or damage.Â
Step -3 : Identify common faultsÂ
Next step is to Identify the faults in the machine. The analysis of the vibration data can help to identify faults and defects in the equipment, such as unbalance, misalignment, bearing faults, resonance, and looseness.Â
We had already discussed a detailed post on identification of common faults in machine i.e. Common faults we detect by vibration analysis?.Â
Step-4: Diagnose the root cause of the faultÂ
Once faults are identified through vibration analysis, it is important to diagnose the root cause of the fault. This involves identifying the underlying reason for the vibration or abnormality in the machinery. Without identifying the root cause, it is difficult to effectively address the issue and prevent it from recurring.Â
It is important to follow a pattern for diagnosing the root cause of a fault. Such as the following pattern as mentioned below.Â
Review the vibration data: Carefully review the vibration data and identify any patterns or trends that may be indicative of a specific fault or defect.
Identify the frequency of the vibration: Identify the frequency of the vibration and compare it to the operating frequency of the machine. If the frequency is synchronous with the machine's operating speed, it may be indicative of a fault related to the rotating components.
Analyze the vibration waveform: Analyze the vibration waveform to identify any irregularities or patterns that may be indicative of a specific fault or defect. For example, high levels of vibration at specific frequencies may be indicative of bearing wear or gear damage.
Inspect the machine: Inspect the machine and its components to identify any visible signs of wear or damage that may be consistent with the vibration data.Â
Reviewing historical data: Reviewing historical data on the machinery, such as maintenance records, can help identify trends or patterns that may point to the root cause of the fault.
Perform additional tests: Conducting additional tests and measurements, such as oil analysis or temperature measurements, can help to identify the root cause of the fault.
Determine the severity of the fault: Determine the severity of the fault and evaluate the potential impact on the machine's operation and performance.Â
Step 5: Determine the severity of the faultÂ
Determining the severity of a fault in vibration analysis is an important step in deciding what actions to take to address the problem. Let us see some common methods in order to determine the severity of a fault.Â
Amplitude: The amplitude of the vibration is a key indicator of the severity of the fault. Typically, higher amplitude vibrations indicate more severe faults. The amplitude can be compared to established vibration standards or to baseline measurements taken when the machine was in good operating condition.
Frequency: The frequency of the vibration can also indicate the severity of the fault. High-frequency vibrations typically indicate more severe faults than low-frequency vibrations.
Time: The duration of the vibration can also be an indicator of the severity of the fault. Longer periods of vibration may indicate more severe faults.
Context: The context of the machine's operation can also be used to determine the severity of a fault. For example, a fault that occurs during a critical operation may be considered more severe than one that occurs during routine maintenance.
Comparison to historical data: Comparing the current vibration data to historical data can also help determine the severity of the fault. If the vibration levels have been increasing over time, it may indicate a more severe fault.Â
Determining the severity of a fault in vibration analysis requires careful analysis of the vibration data and consideration of the machine's operating context. By accurately determining the severity of the fault, maintenance personnel can make informed decisions about the appropriate corrective actions to take, such as scheduling maintenance or repairs, or even shutting down the machine to prevent catastrophic failure.Â
Step 6 : Prepare a maintenance planÂ
In vibration analysis, once the severity of the fault and the root cause have been identified, a maintenance plan can be prepared to address the issue. One can prepare the maintenance plan considering the following points in mind.Â
Determine the appropriate corrective action: Based on the severity of the fault and the root cause diagnosis, determine the appropriate corrective action. This could include anything from simply monitoring the vibration levels to scheduling maintenance or repairs.
Develop a schedule: If maintenance or repairs are necessary, develop a schedule for completing the work. This should take into account the impact on the machine's operation and any potential downtime.
Plan the work: Plan the work that needs to be done, including any necessary parts or equipment, as well as the personnel and resources required to complete the job.
Document the plan: Document the maintenance plan, including the corrective action to be taken, the schedule for completing the work, and any necessary resources or personnel. Â
Step 7: Verify the effectiveness of the maintenance
After completing maintenance in vibration analysis, it is important to verify the effectiveness of the maintenance by re-analyzing the vibration data to ensure that the fault has been eliminated.Â
Let us see some steps that can be taken to verify the effectiveness of the maintenance. These steps are as mentioned below.Â
Collect vibration data: After completing maintenance, collect new vibration data from the machine to compare against the baseline data.
Compare data: Compare the new vibration data to the baseline data collected before the maintenance was performed. Look for any changes in vibration levels or frequencies that may indicate the fault has been eliminated or reduced.
Analyze data: Analyze the new vibration data to identify any new patterns or trends that may indicate the presence of a new fault or problem.
Perform additional tests: If necessary, perform additional tests, such as oil analysis or thermography, to further verify the effectiveness of the maintenance.
Document results: Document the results of the post-maintenance vibration analysis and any additional tests performed.
By verifying the effectiveness of the maintenance, maintenance personnel can ensure that the machine is operating within acceptable vibration levels and that any faults or problems have been eliminated or reduced.Â
If the post-maintenance vibration analysis reveals that the fault has not been eliminated or that new faults have emerged, additional corrective action may be necessary to ensure the reliable operation of the machine.
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