Basics of Vibration Analysis

Acquiring vibration data is only part of the challenge of vibration measurement; the other part is the analysis of the data acquired. It’s important to understand the types of waveforms associated with vibration analysis, the important differences between them and when it is appropriate to use each type of vibration analysis tool. Here’s a quick overview of some of the basics.

Time Domain Vibration Analysis Vibration analysis starts with a time-varying, real-world signal from a transducer or sensor. Analyzing vibration data in the time domain (amplitude plotted against time) is limited to a few parameters in quantifying the strength of a vibration profile: amplitude, peak-to-peak value, and RMS, which are identified in this simple sine wave. The peak or amplitude is valuable for shock events, but it doesn’t take into account the time duration and thus the energy in the event.The same is true for peak-to-peak value with the added benefit of providing the maximum excursion of the wave,…

Guide to Dynamic Balancing

his post is the second in a monthly series of “How It Works” articles that detail the inner workings of motor maintenance services and processes. Large motors are sophisticated machines, and their failure can be deeply disruptive to the rest of a facility’s operations. Understanding how your motor works — and the preventative and predictive maintenance that can make it work better — can both enhance the life of a motor and decrease its energy consumption. Rotating Machines and Vibration
Anyone who works with rotating equipment knows that proper alignment and balance are key to its function. Improper dynamic balance — the most frequent type of balance problem — can cause excessive vibration, which in turn can damage the machine. Balance problems can produce: Unwanted noiseUnnecessary vibrationEarly bearing wearStructural damageInefficient operationsEquipment failureUnnecessary downtimeHigh repair expensesOn-site Balancing Large motors can’t simply be sent back to a manuf…

Beginner's guide to ultrasonic level transmitter

Sonic is the sound we can hear. Ultrasonic is the sound above the human hearing range. A human can hear a maximum up to a frequency of 20 KHz. Ultrasonic frequencies are above 20 KHz. Ultrasonic waves are used to measure the level of liquids and solid objects in industries. Ultrasonic level measurement is the contactless principle and most suitable for level measurements of hot, corrosive and boiling liquids. The normal frequency range used for ultrasonic level measurements is within a range of 40 ­ 200 KHz.
1. What is the principle of ultrasonic level measurement?
Ultrasonic waves detect an object in the same way as Radar does it. Ultrasonic uses sound waves, and Radar uses radio waves. When the ultrasonic pulse signal is targeted towards an object, it is reflected by the object and echo returns to the sender. The time traveled by the ultrasonic pulse is calculated, and the distance of the object is found. Bats use a well-known method to measure the distance while traveling. The ultr…

Ultrasonic Thickness Measurement

In the field of industrial ultrasonic testing, ultrasonic thickness measurement (UTM) is a method of performing non-destructive measurement (gauging) of the local thickness of a solid element (typically made of metal, if using ultrasound testing for industrial purposes) basing on the time taken by the ultrasound wave to return to the surface. This type of measurement is typically performed with an ultrasonic thickness gauge. Ultrasonic Testing (UT) uses high frequency sound energy to conduct examinations and make measurements. Ultrasonic inspection can be used for flaw detection/evaluation, dimensional measurements, material characterization, and more. To illustrate the general inspection principle, a typical pulse/echo inspection configuration as illustrated below will be used. A typical UT inspection system consists of several functional units, such as the pulsar/receiver, transducer, and display devices. A pulsar/receiver is an electronic device that can produce high voltage elect…

Dynamic Balancing In Electrical Motor

Mechanical Faults: Bearing Problems: ☛   Fundamental Train Frequency (FTF)
☛   Ball rotation frequency (BSF)
☛   Ball passage frequency, outer race (BPFO)
☛   Ball passage frequency, inner race (BPFI) Shaft Bend: Shaft ovality, shaft wear or damage Bearing housing looseness:Eccentric Rotor: An eccentric rotor, which means the rotor core OD is not concentric with the bearing journals. Unsymmetrical Air Gap Around Rotor reference with stator produce uneven force at rotational speed (1x Speed). Electrical motors have the same mechanical faults that like other rotating machines, but there are also some specific faults for electrical motors. Thermal bending of the rotor: Uneven electrical circuits in the rotor bars generates an uneven heat distribution in the rotor. This causes a deformation, bending, of the rotor which results in unbalance. Eccentricity in the air gap: If the air gap is not uniform it generates unbalance forces on the rotor which in turn induce a vibration at 120 Hz (2xLF). …

On Site Laser Alignment

Anytime two shafts are coupled together, the importance of precision shaft alignment is paramount. There are several ways of accomplishing this goal but the fastest, most accurate method is the use of lasers. The reasons have not always been obvious, but in the modern world the necessity of alignment is common knowledge. With today’s optimized machinery, alignment is a vital part in the daily maintenance work. Machines need to be online continuously with a minimum of interruptions. A machine breakdown causes devastating loss of production. Nearly 50% of all machine breakdowns are caused by misalignment. Shaft alignment can be performed with different tools. The easiest way is to use a ruler or a straight edge over the two coupling halves and align by eyesight. The result is not very accurate and it is very operator dependent. A better result can be achieved by the use of mechanical dial indicators. A skilled and experienced operator can obtain good and reliable measurements, but it t…

On Site Vibration Analysis & Field Balancing

The protection, consistency and effectiveness of rotating machinery are of a key apprehension in industries.  Condition monitoring of a machines helps to retain the effectiveness and performance of a machine to its optimal level. The condition monitoring of a rotating machine is efficient, but often it is difficult and labor intensive task for maintenance crew to troubleshoot the machine. Vibration analysis is a method used for condition monitoring of the machine. Effective vibration signal extracting techniques have a critical part in diagnosing a rotating machine. Many vibration signal extracting techniques have been proposed during past some years. The paper presents review of some vibration feature extraction methods applied to different types of rotating machines. Condition monitoring (or, colloquially, CM) is the process of monitoring a parameter of condition in machinery (vibration, temperature etc.), in order to identify a significant change which is indicative of a developing …