Are the measurement of the unit’s axial vibration and axial displacement the same thing?

It’s not the same thing, but it’s related. There is a certain allowable value for axial vibration; axial displacement is a consequence that results from it

Of course they are not the same thing; shaft displacement is used to monitor the wear of the rotor thrust bearing surfaces, while axial vibration refers to one direction of vibration.

Vibration measurement focuses on indicating the smoothness of shaft operation, while shaft displacement measurement is primarily used to monitor the relative position of the shaft during operation; they are different. Additionally, vibration measurement can detect vibration velocity, acceleration, and second acceleration； The unit for measuring displacement is mm or um, which are units of length

So I noticed that for our unit, shaft vibration and displacement seem to be related to some kind of sensor, right?

For the vibration and displacement measurement of large-scale machinery, there are shaft displacement (axial) and shaft vibration (radial). I haven’t heard of axial vibration before; how does it arise?

In the case of an eddy current probe, axial displacement is calculated from the DC voltage output (compared to the voltage corresponding to the original installation clearance), while axial vibration is calculated from the AC voltage output.

These are two forms of manifestation of bearing vibration in a device; different forms can be chosen based on the frequency. For low frequencies, vibration velocity is generally used, while for high frequencies, vibration displacement is a better indicator of the magnitude of vibration. The frequency can be calculated from the rotational speed

Axial vibration includes axial vibration displacement, vibration velocity, and vibration acceleration; in other words, axial displacement is a way of representing axial vibration. If your thrust bearing is a sliding bearing, axial displacement is generally measured ； If your thrust bearing is a rolling bearing, then the axial velocity or acceleration is generally measured. Of course, vibration displacement, vibration velocity, and vibration acceleration are not independent of each other; in many cases, vibration velocity and displacement are determined by measuring the acceleration with a vibration acceleration sensor and then performing a series of mathematical calculations.

Brother, your answer is completely wrong: in units equipped with axial displacement, the thrust bearings are definitely sliding bearings； Axial displacement: The axial displacement of the rotor relative to the installation zero point, which indicates the relative position between the rotor and the stator. It is used to monitor the magnitude of the axial thrust as well as the wear level of the sliding bearings. It represents the DC output of an eddy current sensor; there are no concepts of frequency or phase, and it is sensitive to the accuracy of the zero point ； Axial vibration: The peak-to-peak displacement of axial vibration relative to the equilibrium position is the AC output of the eddy current probe; it involves concepts of frequency and phase, and is not sensitive to the accuracy of the adjustment of the 0 position (original gap voltage). Sorry, that’s incorrect; please correct me.

I often see Bone Brother’s insightful analyses in Shao Feng’s group. As for Bone Brother’s expertise in vibration analysis, I can only express my admiration for him. Therefore, please allow me to pay my respects here first~~~~ Since Brother Gu asked, I’ll take the liberty of discussing this with him: First of all, the sources of the above individual statements are as follows: 1. Axial vibration includes axial vibration displacement, vibration velocity, and vibration acceleration; in other words, axial displacement is a way of representing axial vibration. Refer to ISO 10816-1-1995, 3.1.2, Measurement Quantity. 2. If your thrust bearing is a sliding bearing, axial displacement is generally measured ； Referring to Table 7 of API 610 (10th edition), which outlines the vibration limits for cantilever pumps and pumps with supports at both ends, it can be seen that when hydrodynamic support bearings are used, the vibration limit value is given in terms of displacement Af. If your thrust bearing is a rolling bearing, then the axial velocity or acceleration is generally measured. Well, first of all, this is the conclusion reached after consulting two service technicians from Sulzer in Brazil; it also aligns with the limitations regarding the number of times a pipeline can be used. So, in terms of wording, it says “generally,” not 100% certainty. 3. Of course, vibration displacement, vibration velocity, and vibration acceleration are not independent of each other; in many cases, vibration velocity and displacement are determined by measuring the acceleration with a vibration acceleration sensor and then performing a series of mathematical calculations. For this, you can refer to Chapter 1, Section 2, \"Vibration Displacement, Velocity, and Acceleration\", in the book \"Vibration Analysis of Rotating Machinery and Its Engineering Applications\" written by Yang Jiangang and published by China Electric Power Press in 2007. Taking the first and second derivatives of the displacement signal with respect to time respectively yields the vibration velocity and acceleration. ” In Section 4 of the book, it is stated that: \"Based on the relationship between displacement, velocity, and acceleration, an acceleration sensor can be used to highlight changes in the high-frequency components or pulse components of fault signals, whereas an eddy current sensor can be used to highlight changes in the low-frequency components of such signals.\" ”I personally use an acceleration sensor, so I mentioned “in many cases”; this does not mean that eddy current sensors are denied. Haha, it seems there’s a misrepresentation and some misunderstandings; I hope Brother Guo can give me some guidance.