Bearing envelope analysisVibration analysis to detect and diagnose faults in bearings and gears

Bearing analysis introduction

In manufacturing or processing plants with rotating equipment, bearing failures are the most common machine fault. Vibration analysis is essential for diagnosing these issues, as it helps with condition monitoring and fault detection of rolling element bearings. Bearing Envelope Analysis (BEA) identifies and diagnoses bearing faults by extracting periodic impacts from a machine’s vibration signals.

Dewesoft’s Envelope Analysis provides a cost-effective solution by combining high-quality data acquisition units with powerful software. It offers an easy-to-use interface, fast configuration, and includes features like a recorder, bearing database, customizable envelope settings, adjustable signal bandwidth, and predefined bandwidth options (Envelope 1-4).

Supported sensors

Dewesoft data acquisition support a wide range of industry-standard accelerometers including those with differential voltage, IEPE, and charge outputs. Our patented DualCoreADC® technology allows for the measurement of a broad range of signal amplitudes without needing to switch between ranges. Additionally, with an extra counter per channel (ACC+), you can measure both vibration and RPM in full synchronization, all in a compact format.

Key features:

• Connector type: BNC, DB9 or LEMO connectors

• Input options: Voltage, IEPE, Charge

• Supported sensors: Single or multi-axial accelerometers

• Speed and RPM acquisition options: Tacho, tape sensor, encoder, geartooth, or any RPM sensor with a 5V TTL signal output

• Speed and RPM acquisition inputs: Counter, Analog in with Angle Math

This setup ensures versatile and accurate measurements for a variety of applications.

Additionally, our DAQ systems provide support for TEDS sensors, making sensor connection and configuration plug-and-play.

Bearing and gear analysis

Envelope acceleration is a powerful technique used to demodulate high-frequency acceleration spikes into characteristic frequencies associated with bearing faults and gear mesh patterns. This allows for the detection of faults such as cracks, wear, and misalignments within rotating machinery components.

Dewesoft’s software includes a comprehensive bearing database that contains a wide range of bearing models, making it easy to analyze specific bearings. The database is fully customizable, allowing users to add new bearings as needed, ensuring flexibility for different applications.

The software automatically identifies critical frequencies in the spectrum, such as inner and outer race defects, cage pass frequencies, and gear mesh frequencies. These frequencies are highlighted for each part of the bearing or gear system, making it easier to pinpoint potential issues and ensure timely maintenance.

This advanced diagnostic capability helps improve machine reliability, reduce downtime, and extend the life of rotating components.

Envelope Detection - Energy and Peak Available

The envelope detection algorithm is highly configurable and offers several key features:

• No limit on high-pass filter frequency: Ideal for low-speed rotating machinery, especially when used with the Dewesoft ASI-1xVIB acceleration sensor, which has a flat frequency response from 0 Hz to 10 kHz.

• Energy and peak detection: Both RMS and PEAK values can be calculated, with RMS representing the energy of the spikes, and PEAK capturing the maximum spike value.

The envelope signal can be visualized in various plot types, including:

• Time waveform

• Frequency spectrum (with Hz or RPM on the horizontal axis)

• Order spectrum

This version improves readability with clear structure and highlights key points effectively.

Cursors and Markers Multipurpose Frequency Cursor Functions

The Dewesoft FFT analyzer allows setting multiple processing markers for automatic detection of different parameters. Our frequency analyzer offers the following markers:

• Free marker: Free markers can be freely added. The marker shows us the axis position and the amplitude of the selected graph location.

• Maximum marker: The maximum marker finds the highest amplitude in the spectrum.

• RMS marker: RMS markers will sum up all the FFT lines in the selected band and calculate the RMS value.

• Sideband marker: The sideband marker monitors the modulated frequencies to the left and right from the selected centerline.

• Harmonic marker: Shows harmonics of the fundamental frequency, and can be used to investigate signal distortion and non-linearities. 

• Damping marker: Damping markers are best to use in modal testing when we want to find out how our transfer curve is damped. We select it when we are interested in the quality factor, damping ratio, or attenuation rate of a selected peak.

• Delta marker: shows the difference in channel values between two positions of the marker.

• Kinematic marker: Advanced envelope detection is used to identify bearing frequencies and bearing faults. Kinematic markers simplify fault detection during measurement. Create your own bearing sets in the database. 

• Zoom marker: Easily zoom in the selected region of the channel(s).

• Vector cut marker: Outputs a user-defined region of a spectrum as a new channel.

• Trigger marker: Outputs 0 or 1 depending on if the user-defined trigger level is exceeded by the related signal.

All processing markers work as derived math channels and will create new channels that can be stored and used for additional analysis.

Variable RPM - FFT bearing markers that follow the actual speed

In many modern applications, rotating machinery operates at varying speeds. For example, a cable car may need to reduce speed when wind conditions change. To continue monitoring the condition of the bearings under such circumstances, the FFT markers (outer ring, inner ring, cage, and bearing element) must dynamically adapt to the changing speeds.

The kinematic markers in DewesoftX software provide a solution by allowing users to select an input channel as the basis for calculations. The software continuously calculates and adjusts the ratios between the markers to match the actual speed. Combined with the dynamic “channel limits” feature, users can set conditional limit values tailored to specific speed ranges.

Additionally, DewesoftX can generate dedicated output channels for individual bearing amplitudes, providing a full history of the data. This makes it easy to analyze trends over time and use the values in further mathematical operations.

Order Tracking Analysis

The order tracking module makes it extremely easy to take time-domain data and transform it into the angular (order) domain. It can extract any number of harmonics (amplitude and phase angles) which can be displayed in Bode, Nyquist, 3D FFT, real-time x-y, and orbit plot. The plane view FFT clearly shows the excitation forces, natural frequencies, and all the resonances to give a clear picture of the dynamic behavior of the machine.

Any input can be used: microphone, accelerometer, and even the output of the torsional vibration module (see below). The patented digital counters technology (Supercounter®) provides very accurate and repeatable measurements. Results are represented on a 3D color spectrogram and 2D graph for selected order and phase extraction over RPM.

Learn more about Order Tracking analysis:

• Order Tracking Analysis solution page

• Order Tracking online PRO training course

• Order Tracking Online Manual​​​​​​​

• Order Tracking Webinar

• Rotating Machinery Analysis Webinar

Main features

Order tracking module features:

• Simple and easy to setup

• Dedicated re-sampling method for sharp order separation

• Measurement in the time domain to keep all benefits

• 2D, 3D waterfall in order or frequency domain

• Amplitude, phase extraction

• Recalculation in post-processing

• Phase synchronous rpm input with 12.5 ns resolution

For more information please visit the Order Tracking PRO training online course.