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Category: Faults

Vibration Experts

Unbalance Force

Unbalance Force

Unbalance Force Unbalance force in rotors lead to premature machine failure. Excess unbalance forces cause bearings and seals to fail prematurely. Excessive vibration can cause other problems. It is therefore important to precision balance rotors. We can define the unbalance force in two separate ways. First, Force (F) equals the unbalance mass (m) times the…
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measuring phase with a keyphasor

Measuring Phase with a Keyphasor

How do you use a Keyphasor(TM) to measure phase? We’ll answer that question in this short post. Proximity probes, also called eddy current probes or displacement probes, are used to measure vibration in journal bearings. These probes are permanently installed in the bearing. They measure the distance between themselves and the shaft. Two probes are…
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eccentric sheave

Eccentric Sheave

Diagnosing an eccentric sheave with vibration analysis is easy to do. But you have to be careful not to mistake it for other common machine faults. For example, unbalance also shows up at 1x in the radial directions. Fortunately, you can always stop the machine, mount a dial indicator and measure the run out of…
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Diagnosing Bent Shaft

Diagnosing a bent shaft with vibration analysis is easy to do, especially when you can visualize it using 3D animations. Sign up for a course and learn more: https://zencovibrations.com/events/ A bent shaft causes shaft rate vibration (1x) in all three axes. Depending on the location of the bend, one might also see an elevated 2x…
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Detecting Angular Misalignment

Why does angular misalignment produce a 1x (shaft rate) vibration in the axial direction? Why is this vibration out of phase on the bearings on either side of the coupling? It’s easy to understand if you think about it from the point of view of a bolt holding the coupling faces together. As the bolt…
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