Equipment failures may arise during the most unexpected times. When this happens, it could lead to unplanned downtime in production and expensive replacement of inefficient parts. In addition, machine failure may also lead to environmental and safety concerns. However, these situations may be avoided by applying predictive maintenance techniques. This process for monitoring equipment efficiency allows you to identify any deterioration in the machine. With regular monitoring of equipment, you can avoid unplanned maintenance and expensive operational costs.
What Is Vibration Analysis
Vibration monitoring or analysis is the most widely utilized predictive maintenance techniques, and this process can be applied to various types of rotating equipment. Machine vibration is produced in many sources such as gears, bearings, and unbalance. These sources can have a serious effect on the overall vibration of the machine, depending on the resonances, damping, and transfer function.
Each vibration source has unique characteristic frequencies. In simple machines, for instance, it may be possible to use vibration analysis at low speeds. This technique is used frequently on wind turbines, where rotor speed ranges between 5 and 30 rpm. Wind turbines generate bearing defect and gear mesh vibration frequencies. However, the complex vibration signals can be challenging to analyze.
Categories of Vibration Analysis
Vibration analysis can be characterized into of three categories such as detection, prognosis, and diagnosis. Detection uses a basic method of vibration measurement, where the level of vibration is measured by using a broadband source. Typically, the range used is 10 to 1000Hz or 10 to 10000Hz. When machines have little vibrations, the “spiky” appearance of the vibration frequency revealed by the Crest Factor may imply early signs of defects. When there is high energy level presented by the RMS level may show serious defects in the machine. This form of measurement may be useful for trending or plotting the vibration levels to predict the right time for the machine to be repaired.
Broadband vibration measurement may also serve as a way to detect or identify faulty machines. This will allow specialists to diagnose or indicate the cause of the fault such as bearing damage, misalignment, or deterioration. Vibration measurement can also be used with frequency analysis in indicating the source and development of a fault.
Upon detection and diagnosis of the fault, specialists give a prognosis on the possible failure or remaining life of the equipment. However, it is important to monitor the fault regularly to determine the time when the machine may experience similar issues or when it is necessary to take the equipment out of service.
Benefits and Limitations of Vibration Analysis
Vibration analysis can be done simply by measuring the Root Mean Square (RMS) vibration of the bearing housing. A wide frequency range of 10 to 1000Hz is used to measure the vibration. The measurements obtained can be trended for a certain period, and these will be compared with pre-alarm, alarm levels, or other known vibration levels. Trending can help indicate any change in the machine’s overall condition. Vibration measurement can also be compared by using general standards.
Early signs of bearing defects can be detected by using the Crest Factor. When the fault develops, short bursts or peaks of high energy are formed. These bursts increase the level of vibration signal, although there may be insignificant effects on the RMS level. As the fault becomes severe, more peaks are produced and these cause a decrease in the Crest Factor.
Although this predictive maintenance technique may use simple methods and have low-cost features, vibration measurement may be less sensitive in detecting initial stages of defects. In most cases, the technique is suitable for diagnosing advanced conditions of faults. Incipient defects produce low vibration, and any changes in the bearing condition may be difficult to identify.
With great demands on increased efficiency and high quality output, it is important to understand the overall condition of machines or equipment in the facility. Vibration analysis allows you to detect faults, so you can come up with an effective maintenance strategy. Your company can prevent untimely machine failure and expensive repair or replacement costs. With predictive maintenance techniques such as vibration analysis, your company will have an increase in production, zero instances of unplanned equipment failure, and a high return on investment.
What about you? Does your company implement a predictive maintenance program? Why or why not?