Delving Deeper: ISO 15243 Failure Modes and their Vibration Signatures

In my career I saw many vibration engineers, reliability engineer, mechanical and electrical engineers not being able to related condition monitoring data with the Rolling Bearing failure mode which has happened and how far they can run that bearing till they stop and check the bearing for failure analysis which in many cases the bearing could still be used for some time more.

So I decided to make this article to combine my Bearing failure analysis knowledge and vibration analysis knowledge for your use.

Delving Deeper: ISO 15243 Failure Modes and their Vibration Signatures

While ISO 15243 standard excels at classifying bearing failure modes through physical inspection, vibration analysis offers a complementary perspective. This article explores the vibration characteristics associated with each sub-category of failure mode defined in the ISO 15243 standard. It's important to remember that vibration analysis has limitations, and a multi-faceted approach is crucial for accurate diagnosis.

ISO 15243 Failure Modes and Potential Vibration Signatures:

Rolling Contact Fatigue: This widespread failure occurs when cyclic stresses cause gradual material deterioration.

Vibration data might reveal:

• Increased Overall Vibration: Early fatigue might present subtle overall vibration level increases. As fatigue progresses, these increases become more significant.
• Specific Frequency Peaks: Characteristic peaks corresponding to the damaged component (races or rolling elements) and rotational speed can emerge. The specific frequency depends on the defect location and bearing geometry.
• Modulation: Amplitude variations (modulation) caused by component meshing might occur, especially with localized defects.

Wear: The type of wear significantly impacts the vibration signature:

• Abrasive Wear: Increased broadband vibration, indicating a wider range of excited frequencies, is a potential sign.
• Adhesive Wear: This wear mechanism can lead to impacting pulses in the vibration spectrum due to debris generation and potential skidding between surfaces.
• Wear on the Cage: This can introduce rattling noises and higher frequencies in the spectrum as the cage impacts other bearing components due to increased clearance. The severity of vibration increase typically reflects wear progression.

Corrosion: Corrosion mechanisms like pitting and fretting can manifest in vibration data as:

• Broader Frequency Bands: Increased surface roughness due to corrosion can lead to a broader range of excited frequencies, causing the vibration spectrum to appear "fuzzier."
• Impulses at Specific Intervals: Pitting corrosion, with its characteristic pattern of defects, might introduce impulses at specific intervals in the vibration spectrum depending on the defect's spacing and rotational speed. The extent of vibration increase depends on the severity and location of the corrosion.

Surface Distress: This category encompasses various wear mechanisms that can cause distinct vibration signatures based on the specific type:

• Electrical Discharge Machining (EDM): This distress mode, often caused by stray currents, can introduce high-frequency electrical noise into the vibration spectrum.

• Brinelling: False brinelling, characterized by indentations, can cause impacting pulses at specific intervals depending on the defect pattern and rotational speed.

Fatigue Fracture: This catastrophic failure mode can present with:

• Sudden Increase in Overall Vibration: A sudden and significant increase in overall vibration levels might indicate a fracturing component, requiring immediate attention.
• Impacting Events: Depending on the fracture severity, impacting events might be evident in the vibration data, potentially accompanied by audible noises.

Remember:

• Vibration analysis is a valuable tool, but it's not foolproof. Multiple failure modes can exhibit similar characteristics. Combining vibration data with other condition monitoring techniques (oil analysis, temperature monitoring) and operational factors is crucial for accurate diagnosis.
• Baseline vibration spectra collected during healthy operation are essential for identifying deviations that might indicate developing problems.
• Early detection is ideal, but some failure modes might not produce distinct signatures until a later stage.