Due to the very high demands on availability and the efficiency of production and industrial systems, condition-based maintenance (CBM) is becoming increasingly important. The use of condition monitoring tools increases machine availability, reduces maintenance costs, and enhances process quality.
Until now, the installation of industrial sensors to monitor conditions has been complex and cost-intensive. Many of the monitoring systems on the market are application specific and expensive. That’s why iQunet has introduced our award-winning, micro-electro-mechanical systems (MEMS) condition monitoring sensors. As they are battery powered and wireless, they make CBM very practical and cost-effective.
MEMS-based sensing elements are gaining wider acceptance and being adopted for static and dynamic (mobile) applications. A recent increase in demand for reliable wireless sensing nodes has created demand for alternatives to expensive accelerometers for multi-control and monitoring tasks. Owing to their size and cost, MEMS accelerometers are an effective alternative option.
In machinery-condition monitoring, accelerometers are often used to measure vibration (acceleration) signals. They can be programmed to detect any deviation from normal signatures. Vibration waveforms are interpreted and processed in a variety of ways. This can include detecting peak values and variations in the signal over time or performing a power spectral analysis in the frequency domain.
Vibration has traditionally been sensed using piezoelectric accelerometers. While accurate and reliable, they have some inherent problems. They are difficult to mass-produce and have high source impedance which means that their signal must be very carefully amplified. The use of traditional piezoelectric accelerometers for simultaneous and multiple data collection points is considered to be impractical. Cost is a significant issue due to the price of the individual units and the requirement for associated electronic signal conditioning units and hard wiring.
With increasing demands for wireless sensing nodes for asset control and condition monitoring, the need for cost-effective alternatives has risen. MEMS accelerometers are the best option because of their small size, newer technology, and lower cost.
MEMS sensors have proven performance: the low cost and excellent reliability of MEMS sensors is creating safer, better-handling automobiles. Many automotive systems now make extensive use of MEMS inertial sensors. More than a billion sensors have been utilized in automotive applications over the last 25 years and they have shown a high degree of quality and reliability. Systems with MEMS sensors can detect crashes from any direction and activate seatbelt tensioners and airbags to protect occupants. iQunet is using this MEMS technology in innovative vibration sensors.
MEMS accelerometers are the solution for the practical deployment of smart sensing technology. Smart sensors (also known as transducers) provide more complex functions than raw signals as they integrate systems into the sensing architecture. iQunet’s smart sensors feature programmable signal conditioning (see the Want to ‘hear’ more case study below), onboard signal processing and analysis, simple decision making, and remote communication. And all powered by just two small batteries!
Within ArcelorMittal there are thousands of motors and pieces of rotating equipment that must be maintained in top condition. Recently an iQunet CBM sensor was able to detect equipment failure quickly, keeping downtime to a minimum.
Bearing damage is often caused by stray electrical currents which are generated within the machine. Known as ‘bearing currents’, they occur when the voltage on the shaft starts to accumulate on the rotor. When that current exceeds the dielectric capacity of the bearing lubricant, it discharges through the bearing. After discharge, the voltage continues to accumulate on the shaft and the cycle repeats itself.
This random and frequent discharging has an effect known as electric discharge machining (EDM). EDM causes pitting of the bearing’s rolling elements and raceways. Initially, the discharges create a ‘frosted’ or ‘sandblasted’ effect. The first symptom of bearing current damage is the audible noise created by the rolling elements riding over the pits in the bearing race. If it is allowed to continue, EDM will result in complete bearing failure.
At ArcelorMittal we installed some iQunet CBM sensors on critical equipment at its mill in Gent, Belgium. The motor below was quickly replaced when an iQunet CBM sensor detected an unusual signature, allowing downtime to be kept to a minimum.
How do we reach good results with MEMS sensors? Well, by using state of the art mathematics and innovative filtering. One step is shown below: the upper time signal is the raw signal from the “fluting” bearing. The lower time signal is an image after static is cancelled out. Both signals contain the bearing faults. But we guess you will “hear” the difference with or without our preprocessing. Click on the loudspeaker icon to run the demo. The red bars are showing the “hidden” frequencies.