Enhancing the Reliability of Mining Equipment with Condition Monitoring.
By Harshvardhan Singh
Mining is a unique field, as what matters the most is mining equipment’s availability – everything from production to backfilling to development depends on it.
With most of mining equipment providers moving from Annual Maintenance Contract (AMC) to Cost Per Hour (CPH), the pressure on service division working on the field is at an all-time high. The service team requires a group of energetic and realistic management team to accurately plan, schedule and measure maintenance work.
Specific formalised monitoring systems must be utilised as it’s the need of the hour. Predicting and preventing machine breakdowns or failures should be the prime focus. Condition monitoring is one such tools that can be utilised to bridge any gap in maintenance practices.
As the name suggests, condition monitoring refers to health check-up or a check of machine’s condition at regular intervals while they are still running. Condition monitoring can help a service organisation determine what maintenance practices needs to be carried out to prevent failure of a part.
There are five main condition monitoring techniques used in mining industry.
Oil analysis: Lubricant can be considered as blood for machines. Any abnormality in lubricant can cause reduction in machine efficiency and reliability. Oil analysis refers to analysis of lubricant via high precision scientific instruments for contamination, property and additive composition.
It’s a predictive maintenance tool that has been used by industry for many years. Oils from machines are periodically tested to determine their suitability for continued use.
Oil analysis starts with taking a sample of desired lubricant from the machine. The sample can be taken via three methods – Sampling port, drop tube and drain plug.
- Sampling port comes with a female protection plug and an adapter that can be installed in any critical component like engine, transmission for drawing lubricant. In some machines it can come preinstalled from manufacturer. Oil sampling via sample port is easy and quick, also their availability in different sizes make them convenient for use in any machine.
- The suction tube method requires a suction pipe of suitable diameter and length which can be inserted inside the component’s sump and via a vacuum pump, a desired quantity of lubricant can be sucked.
- The drain plug method is the capturing of a lubricant sample from drain port after some volume of the lubricant has purged. Sampling via drain plug should be avoided as small concentration of sediment, debris and particles that settles down in the bottom can enter the sample bottle.
After sample collection, a sample data sheet is filled and then the sample is sent to laboratory for analysis. At the laboratory, characteristics of withdrawn samples is evaluated by oil analysis techniques such as spectroscopy, infrared, X-ray diffraction, chromatography, ferrography and many others.
Oil analysis can be of great boon for machines if initiated, implemented and maintained properly.
Vibration analysis: It is a technique of measuring vibration using a vibration sensitive transducer and instrumentation to detect abnormalities in rotating machinery.
The data collected can be recorded and used for further analysis. It can then be used for troubleshooting, root cause failure analysis, as well as quality control issues.
Though considered as a pioneer tool of condition monitoring, it has certain limitations such as:
- Pinpointing of fault is difficult.
- Crack propagation is difficult to track.
- Skilled analyst and quality vibration analysis setup is required.
Infrared thermography: A thermometer is used to detect fever by measuring body temperature, similarly abnormalities in machines can also be detected by measuring their surface temperature. Temperature is a common indicator of equipment’s health. All equipment’s when new or when maintained well have a normal heat signature (considered as the baseline).
As the equipment ages, internal parts and components also deteriorate thereby increasing resistance. As the resistance increase, friction increases thereby increasing heat. Cracks, melt, wear, fracture, fatigue in material and operational environment are some of the other contributors to thermal elevation. Through infrared thermography, these deviations from the baseline can be measured and early repair of equipment flaws can be conducted.
Pressure monitoring: A hydraulic system is designed to operate at set pressure. Pressure gauges are used for set-up and tuning of hydraulic component’s such as pumps, valves, accumulators and many others. Gauges also help in troubleshooting a hydraulic system. Any abnormalities in the form of contamination or leakage can bring about deviations in set pressure. Gauges help in detecting these pressure changes.
Acoustic emission monitoring: This technique is also used for condition monitoring of equipment’s. Acoustic sensors are mounted on equipment under inspection. External pressure, temperature and loading is applied on test component leading to generation of acoustic stress signals. These signals are converted to electric signals and then analysed to localize defects in component.
Harshvardhan Singh works as a senior service engineer at a mining firm in India. He is currently working in the oil analysis field. He has worked in the field of tribology and lubrication and loves to write about the same.
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