General machinery vibration severity chart

Birla Goa Campus, Goa, India. Journal of Vibroengineering, Vol. Received 1 November ; received in revised form 24 December ; accepted 20 January ; published 15 February Development of predictive model for vibro-acoustic condition monitoring of lathe.

Present day requirements for enhanced reliability of rotating machinery have become critical for the manufacturing sector. Every rotating machine exhibits a unique characteristic vibration and acoustic signature. This can be used to identify the defective parts and estimate the present severity of the problem; most importantly, without opening the machine for inspection. Moreover, it aids in the reduction of unscheduled down time, turnaround time and existing noise levels.

The paper deals with the vibro-acoustic condition monitoring of metal lathe and development of predictive models for the detection of probable faults using Machine Learning.

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Experiments were conducted to obtain vibration signatures using accelerometers and the data was further processed while the acoustic signatures were obtained using noise level meters. Results were obtained for idle running, turning and facing operations using a single point cutting tool for constant spindle speeds, feed and depth of cut. The vibro-acoustic signatures of six metal lathe machines were collected over a period of 5 months and the trends obtained were analyzed.

The filtered acceleration g-peak signatures were compared with the General Machinery Vibration Severity Chart and based on the velocity classification results, the best machine was chosen for the development of predictive models. Vibration as well as acoustic signatures were isolated using filters, empirical relations and manufacturing data. Predictive models were made using machine learning algorithms to predict the failure of the lathe based on its historical data.

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These models can be used by industries to detect unhealthy trends and identify troublesome parts in the machine which can be then scheduled for maintenance thereby decreasing production downtimes. Keywords: vibration, acoustics, condition monitoring, machine learning, predictive model, maintenance. Approximately half of all operating costs in most processing and manufacturing operations can be attributed to maintenance.

As a result, machine condition monitoring systems have been gaining considerable importance in the manufacturing industry [1], since they allow for a significant reduction in the machinery maintenance costs, and most importantly, the early detection of potentially disastrous faults. Besides the detection of the early occurrence and seriousness of a fault, it aids in the identification of components that are deteriorating; most importantly, without even opening the machine for inspection.

Machine condition monitoring can be defined as a field of technical activity in which selected physical parameters, associated with machinery operation, are observed for the purpose of determining machine integrity []. Once this has been estimated, maintenance activities can be scheduled only when needed, which results in optimum use of resources.

The main reason for employing machine condition monitoring is to generate accurate, quantitative information on the present condition of a machine, here the lathe, in order to optimally schedule maintenance, achieve maximum productivity, and still avoid unexpected catastrophic failures.

It also results in improved risk maintenance and increased machine reliability []. The collected vibration and acoustic data is used with machine learning algorithms to monitor the mechanical condition and derive the approximate time of a functional failure of different parts, resulting in scheduled maintenance. Vibration condition monitoring has been a trusted method for the past thirty years [, 9]. However, the time and effort required to obtain machine signatures is much more as compared to acoustic condition monitoring.Related Resources: vibration.

Vibration Engineering And Design. When using the Machinery Vibration Severity Chart, thefollowing factors must be taken into consideration:. When using displacement measurements only filtered displacement readings for a specific frequency should be applied to the chart. Unfiltered or overall velocity readings can be applied since the lines which divide the severity regions are, in fact, constant velocity lines.

The chart applies only to measurements taken on the bearings or structure of the machine.

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The chart does not apply to measurements of shaft vibration. The chart applies primarily to machines which are rigidly mounted or bolted to a fairly rigid foundation. Machines mounted on resilient vibration isolators such as coil springs or rubber pads will generally have higher amplitudes of vibration than those rigidly mounted. A general rule is to allow twice as much vibration for a machine mounted on isolators.

However, this rule should not be applied to high frequencies of vibration such as those characteristic of gears and defective rolling-element bearings, as the amplitudes measured at these frequencies are less dependent on the method of machine mounting.

Membership Register Login. Copyright Notice. Values shown are for filtered readings taken on the machine structure or bearing cap. When using the Machinery Vibration Severity Chart, thefollowing factors must be taken into consideration: 1. Related Resources: Mechanical Vibration and Acoustics. Add a Comment you must be logged in to post comment Register :.Welcome, Private Messages : Unread. Note: Your browser does not have JavaScript enabled. Many features may not work properly without it.

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Latest Topics. Private Messages : Unread. Posted Hope the question makes sense. Tks Karl. Member Registered: Posts: 2, Member Registered: Posts: Karl, Maybe I understood your question.

You ask about the table in the standard that shows limits for different zones based on the support and power. In ISOthis is written "r. Is this your question? If yes, then the limits provided are the overall not the spectral amplitudes.

general machinery vibration severity chart

What you called "peak values" can be misunderstood with the zero-peak method of calculation while you are referring to the individual components filtered amplitudes on the spectrum, I guess. Regards- Ali M. The same sine wave assumption must be made for conversion between velocity and displacement or acceleration. ISO point to another standard normally that defines the specs of the measurement ISO or updatedit is normally not broad band like that or at least not OA, the normal spec is "broad band" but filtered Hz and the filter spec is brand new in the latest 10 years and are now defined in a way that it is actually possible to follow the previous was the same from the 50's I think however for machines less than RPM lower limit should be 2Hz.

Rectification are defined as RMS in most cases but not all. If you see the word "Severity" it may indicate that the number is a compound calculation of acc, vel, amp data, not a direct measurement but not always and not inyet.

If your instrument is digital it may store the TWF and can calculate any number in any way you like or that you can convince the software guy to produce for you Or it can do a hybrid semi cheat and store the signal peak rectified also. There are many ways to skin a bear, specially if it is a digital bear. It is velocity and can be purchased from the ISO organization.This program allows you to calculate bearing defect frequencies and then view them in a spectrum.

See ball spin frequency, inner race, outer race, harmonics and sidebands. Play around with the numbers and see how they effect the bearing defect frequencies and the patterns in the spectrum.

general machinery vibration severity chart

What is the relationship between the Fmax or frequency range you select on your data collector, the number of lines of resolution, the time waveform length, the number of samples and the number of shaft rotations the test will capture? If you want to analyze a gearbox in the time waveform and wish to configure your analyzer to collect three revolutions of the shaft, this calculator will help you determine what Fmax to use and how many lines of resolution you will need.

The utility will also simulate a spectrum with the shaft frequencies and gearmesh frequencies. This simulator will let you play with characteristics of an A.

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What is the relationship to the number of poles, the actual running speed and the slip frequency? How do these characteristics appear in the spectrum when the motor has a problem? How about motor rotor bars?

Where do these appear in the spectrum and what patterns do they create?

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What is the relationship between the number of pump impeller and diffuser vanes and the vibration produced by the pump? What is the relationship between the number of fan blades or compressor vanes and their relationship to fan and compressor vibration? Enter a run speed, number of vanes blades etc. Use the Fmax slider bar to change the frequency range of the plot at the bottom to display the information of interest. Adjust the speed and amplitude of vibration in this animated fan and see how these two varibales effect the time waveform.

As you increase the speed, the wavelength of the sine wave decreases. As you increase the amplitude, the height of the sine wave increases. This simulator will help you to understand the relationship between the movement of the fan and the vibration produced by its movement. We have a new single-plane vector balance program. You can move the location of the trial weight and change its mass.

You can even set your phase convention with rotation or against rotation normal and you can add fan blades to see how the mass should be split between them. The original version of this program was purchased from Steven Young. Slide the bars to control the mass, stiffness and damping in this one degree of freedom mass spring system.

In this simulator you can adjust the speed, amplitude and relative phase between two fans.Vibratio n Diagnostic Chart. Table It includes comments about the amplitude, frequency, phase, and features of each vibration cause.

The data showed that levels recorded at the inboard pump axial and horizontal positions exceeded alarm values defined for these points. Tes t Data and Observations Velocity spectra from the inboard pump bearing showed the majority of the vibration was at 2X rotational speed in the axial direction and at 1 times rotational speed in the horizontal direction.

Misalignment between the motor and pump was suspected, and a coupling inspection was performed. The coupling was found to be out of alignment, as the following readings indicate: parallel side to side was out 0. Two of the four upper bearing housing bolts were also discovered to be loose. Correctiv e Actions The coupling was realigned to the following tolerances: 0. The motor also was raised to a position 0. New bolts were installed on the upper inboard pump bearing housing.

Fina l Results A new set of baseline vibration spectra was collected for this equipment at a later date.

general machinery vibration severity chart

The data showed that alignment greatly reduced the vibration levels. Inboard pump axial vibra- tion dropped from 0. The inboard pump horizontal vibration likewise was reduced from 0.

Calculators & Simulations & Severity Charts

Similar reductions were observed at other motor and pump measurement points. Conclusion Had this misalignment condition continued unabated, it is very likely that the pump and motor bearings would have been damaged. This, in turn, could have led to a catastrophic failure of the condensate pump, consequently derating the unit. It took two workers 12 h to align the coupling. If the bearing needed replacement, it would have taken 3 or 4 workers about 48 h to complete the job.

In summary, correcting this condition before the bearings or coupling was damaged saved the station many worker hours as well as the expenses of new parts and lost production.

Your email address will not be published. Sections About. Categories Home Appliance Repair Uncategorized. Posted on November 23, by admin Leave a comment. View all posts. Special machines:Control Differential Transmitter.Posted at:June 4, [ 4. Vibratio n Velocity.

Vibration Frequency — CPM. Table 1- Vibration Severity Criteria. The fact that vibration velocity is a direct indicator of fatigue and vibration severity is clearly indicated by the General Machinery Vibration Severity Charts. Amplitude is a measure of vibration severity while frequency is a measure of … Describing machine vibration with these general terms is, however, … is simply a chart that shows how the velocity of a vibrating component changes with time.

Vibration tolerances or specifications typically are expressed as either absolute or relative criteria.

Common terminology used for machinery vibration … Overall or Broadband Vibration Severity using Velocity is applicable to all types of general rotating equipment ….

Lubrication charts are available for machines from the manufacturer. The measured Hz RMS velocity …. Vibration Velocity Vrms.

19. Introduction to Mechanical Vibration

Machine …. As a general rule, fatigue failures result ….

general machinery vibration severity chart

Part 1 determines general …. Vibration Severity Charts. All the severity charts have 2 frequency scales. At the top of the chartsfrequency is expressed in Hertz and extends from 1 Hz up to …. Course …. Vibration Parameters — Acceleration, Velocity and Displacement. The form and period of …. General machinery severity chart from Rao. The disadvantages in using these criteria are [Ref. This Chart has been used by vibration analysts for the last 30 ….

Figure 5 is another general chart for judging the amplitude and frequency jointly to determine …. ISO was released in Augustestablishes the general conditions and ….This article discusses an example of an outer race-bearing defect on a 1,ton 4,kilowatt air-conditioning chiller. The defect was detected using off-the-shelf portable vibration analysis hardware and software. The machine is a single-stage centrifugal compressor with a rolling element thrust bearing on the motor free end and a sleeve bearing on the motor drive end.

This article discusses methods used to diagnose and trend the bearing defect using vibration spectra as an indicator of the bearing condition. The diagnostic methods covered are universally applicable to other types of machines pumps, fans, gears with rolling contact bearings. Tools used to measure vibration have improved significantly in the past 25 years. The sensor of choice for most vibration data collection on industrial machinery is an accelerometer.

As the name implies, the output is proportional to acceleration; however, it is normally integrated to display in units of velocity. All data shown in this case history was collected using a triaxial accelerometer cluster shown in Figure 2. Figure 1. Chiller showing the vibration test location on the motor bearing housings. Figure 2. Sketch of a triaxial accelerometer cluster left that is stud-mounted to the bronze disk mounting pad bottom right. The cluster contains three accelerometers, each mutually perpendicular to the others.

Vibration data collection is activated using a bar code that automatically sets up the data collector, collects and then stores the data. The notched mounting pad is adhered rigidly to the motor bearing housing, and the triaxial cluster is stud-mounted, allowing all three axes to be collected simultaneously.

The bar code and mounting configuration allow accurate and repeatable data to be collected every time, regardless of the skill of the person doing the data collection. As long as the test conditions are relatively consistent, the test data also should be consistent if the mechanical condition remains unchanged.

The signal processing techniques used by a vibration analyst vary based on the level of detail desired. In routine predictive maintenance programs, two types of data typically are collected. Overall level: The overall level is a measure of the total vibration amplitude over a wide range of frequencies. An overall vibration measurement, also called a broadband level, is a single value that is relatively easy and cheap to collect, process, analyze and trend. Narrowband: Using a Fast Fourier Transform FFT algorithm, the vibration signal is resolved into a number of discrete frequencies and displayed as a two-dimensional spectral plot of amplitude vs.

All of the triaxial spectra shown in this case history have a frequency scale with lines of resolution. In other words, each spectrum is composed of individual peaks defining an amplitude at a specific frequency. What is an acceptable level of vibration for the 1,ton kW chiller? Vibration tolerances or specifications typically are expressed as either absolute or relative criteria.

The IRD General Machinery Vibration Severity Chart, summarized in Table 1, is the most common example of absolute criteria and is a good guide for engineers who do not have any historical data on a machine. Each increment of machinery condition is represented by change of a factor of two in the vibration velocity. Note that 6 dB also represents a change by a factor of two, so each machinery condition band is represented by a 6 dB differential.

Machinery Condition. Velocity in. Table 1. The tolerances in the chart are for frequencies between 1. While absolute criteria are fine for acceptance testing, more sensitive criteria are needed for making accurate diagnoses as part of a predictive maintenance program.

A relative criterion is best if your goal is to diagnose machine health accurately. Relative criteria are defined by averaging vibration measurements taken on several identical machines, all tested under similar operating conditions. For this case history, the acceptance criteria were constructed by averaging spectral measurements from 12 identical chillers.


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