Predictive maintenance & condition monitoring


as pump farms in oil refineries, where it can make a huge difference in performance: SKF has seen ODR increase mean time between failures (MTBF) by 15 per cent, while cutting maintenance costs by more than 10 per cent. While ODR enhances the contribution from operators, it does not replace the need for traditional sensor-based monitoring. Instead, the two approaches should be used side by side. Experienced operators can also make use of an


app called SKF DataCollect. This ISO standard compliant maintenance and inspections programme extends the diagnostic capabilities of SKF QuickCollect, allowing users to manage and monitor their maintenance tasks and inspection data. They can also register for – and connect to – the SKF Cloud for access to SKF’s remote expert services.


Best asset care


all the basic steps are taken to ensure best results – and this means ensuring that sensors are fitted correctly. Correct mounting of sensors is crucial in order to ensure reliable and consistent readings. An accelerometer should be mounted directly


on the machine on a flat, smooth surface that is larger than the base of the accelerometer. The surface must be free of grease and oil, as close as possible to the source of vibration and perpendicular to the axis of rotation. This helps to ensure the most accurate possible measurements of vibration levels. Where possible, mounting a sensor via a drilled and tapped hole directly to the machine housing will give the best results. If the housing is uneven, a spot facing installation kit allows creation of a flat surface. With sensors correctly installed, key assets are


then ready to be interrogated for their data by technicians using handheld scanners. However, this manual method of data collection is not always sufficient. For continuous vibration and temperature monitoring of non-critical machinery, there is the permanently installed SKF Machine Condition Indicator. This is equipped with LEDs, which illuminate when pre-set thresholds are exceeded – warning operators that further investigation is needed. Internal sensors measure a wide range of critical parameters, including velocity, enveloped acceleration (bearing or gear impulsive vibration) and machine surface temperature.


Better care


Moving up one level, we come to more sophisticated methods of monitoring data, which requires greater insight from machine operators. Because operators work in close proximity to


equipment, they are usually the first to detect slight changes in process conditions and machine health. However, their insights often go unreported – or are not effectively acted upon – which can lead to machine failure, unplanned downtime and higher operating costs. It is a golden rule of predictive maintenance that – once it is up and running – maintenance teams must pay attention to alerts and alarms. Otherwise, the point of installing the system is lost. However, it is critical to balance the


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precision of the monitoring system with the experience of the operator. Here, an SKF solution called the Operator


Driven Reliability (ODR) programme is useful, as it enables a valuable source of machine health data – operator observations – to be effectively collected, analysed and acted upon. ODR is an approach that enables operators to


use their skills and knowledge to detect and report upon early changes in equipment conditions – from abnormal readings and strange sounds to signs of leaks or pressure drops. From their position on the front line, operators play a key role in managing assets and minimising downtime. Having such a system in place boosts performance, but also has a cultural effect on the company: operators better understand the importance of their role, are empowered to make decisions and can appreciate the significance of their actions and findings. There is a good reason for this: sensors cannot


always detect faults. In these instances – such as a leaking face seal – operators must make visual assessments of components and supply this information alongside the automated online data. ODR is vital in keeping components such as pumps and fans running for as long as possible. Skilled operators know their equipment – and will spot things that a sophisticated sensor will miss. ODR has become common in applications such


SKF’s best level of condition-based asset care is the final option. It is deployed when handheld or periodic data collection instruments are considered inappropriate – for reasons such as plant safety, asset value, or the critical nature of the processes and machines being monitored. In this case, it is strategically and tactically beneficial to take your asset and machine health monitoring programme wholly online for expert analysis and recommendation. One key factor of this level of asset care is


the greater level of automation: not only is data collected automatically – with little or no manual intervention – but many of the results are then analysed off site. One reason for this is that there is simply too much data to handle onsite. Alternatively – or in addition – the data may be highly complex and require detailed analysis from remotely-located experts. SKF Remote Diagnostic Services allows any company with Internet access to tap into this expertise: SKF’s asset diagnostic software and hardware is instantly available through its cloud- computing infrastructure, while 24/7 availability of remote experts can help customers make faster, more informed decisions about the health of critical machinery. Of course, condition monitoring is nothing


without instrumentation. An appropriately advanced condition-based monitoring tool for experienced users is the SKF Multilog On-line System IMx-8, a compact, eight-channel version of its IMx machine health monitoring platform. It brings affordable machine health monitoring to a wider industrial user base. Its Event Capture feature is of particular appeal to machine tool users that require a cost- effective crash detection capability. Anybody who is unconvinced by the benefits of


predictive maintenance should consider this: it costs around 50 per cent more to repair a broken asset than it does to address the problem in advance. SKF’s three-level approach to CBM is ideal for many circumstances and machine criticalities. Choosing the correct level for your needs – whether basic, better or best – will ensure that assets can be operated more affordably, productively and profitably.


SKF www.skf.com October 2018 Instrumentation Monthly


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