BEARINGS, SEALS & GASKETS FEATURE


Taking the proactive approach to bearing care B


earings fail for a number of reasons, but chief among them are particle


contamination, inadequate lubrication and misalignment. Collectively, these cause almost three quarters of all bearing failures – but this figure could be reduced significantly simply by making judicious decisions about maintenance approaches and sealing solutions.


LUBRICATION Lubrication is often the ‘poor relation’ of a condition based maintenance (CBM) programme and, even where routine lubrication is carried out, data may not be captured and guidelines fail to specify what, how and when it should be used. Yet the condition of oil can tell you a lot


about the condition of the equipment it is lubricating, so routine testing and analysis should be a fundamental part of any regular CBM programme.


CONTAMINATION Contamination of the lubrication oil by dust particles or moisture is one of the most common and costly causes of premature bearing failure and presents a serious impediment to achieving an L10 life cycle.


Bearing failure due to water ingress


deviation from this can cause equipment malfunction or failure. Misalignment between the shafts of a driver


and the equipment it is coupled to increases the stress on the shafts, leading to excessive wear. Breakdown is almost inevitable and bearing damage is a common by-product. When the cost of repairing or replacing bearings and other components is added to that of lost production, the importance of accurate alignment is obvious.


TECHNOLOGY FOR RELIABILITY Bearing failure is such a common occurrence that some engineers see it simply as a necessary evil to be factored into ongoing maintenance. However, advanced technology presents the opportunity to make a seismic shift away from a costly reactive maintenance approach. The most common cause of bearing failure –


contamination of the lubrication oil – can be all but eliminated by replacing lip seals with labyrinth-design bearing protector seals, which prevent the ingress of dust or moisture into the bearing chamber. These employ the centrifugal force of rotating


Research indicates that water contamination as


low as 0.002% – equivalent to a single drop of water in a typical bearing’s chamber – can reduce bearing life in some oils by as much as 48%. In another example, an oil-lubricated 45mm


radial bearing running at constant load and speed under ultra-clean conditions (nc = 1) can complete 15,250 operating hours. Introduce contaminated conditions where nc = 0.02 and the bearing’s operational life plummets to just 287 hours. Contamination of the oil accounts for more


than 20% of all bearing failures. It therefore stands to reason that, if you can solve this issue, you will have removed a major barrier to bearing reliability.


MISALIGNMENT According to design requirements, machine components are typically coincident, parallel or perpendicular during operation. Any


equipment to open a temporary micro gap, allowing expansion of the oil air mixture in the bearing housing and letting the equipment ‘breathe’. When the equipment stops rotating, the micro gap immediately closes, forming a perfect seal against potential contaminants. They can be retrofitted, require


minimal maintenance and will protect a bearing until it reaches the end of its natural lifespan – estimated to be 12 years or more. With contamination no longer a


threat, more expensive but efficient synthetic bearing lubrication oil becomes a viable investment.


CLOUD BASED CBM Advanced cloud-based technology such as AVT Reliability’s Machine Sentry has created an opportunity to introduce proactive, operator driven CBM practices. Safety and business critical assets can be


managed online, employing high-speed wireless connections to collect diverse data, including vibration and oil analysis. This can


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be collated on one platform from multiple locations, and securely accessed from any location via a standard web browser. A key feature of this technology is its


automated diagnostic assistant (ADA). Informed by thousands of hours of vibration data and extensive field experience of vibration specialists, ADA can predict stage 2, 3 and 4 bearing failure and detect a wide range of other common fault conditions commonly known to reduce reliability or halt production. It proposes an action plan to tackle impending issues before they impact on operations. Common threats to bearing performance, such as poor lubrication or misalignment, can therefore be pre-emptively remedied. The continuous availability of data provides a bedrock for an ongoing maintenance plan. Lubrication can be more effectively managed through the same platform to ensure the smooth functioning of equipment. Failure detection becomes woven into the daily fabric of a maintenance programme, decision-making is better


informed, and assets can be maintained to ensure optimum productivity. It is calculated that, for every £1 spent on ADA technology, at least £5


is saved in terms of time, expertise and hardware and software costs. Over a three- year period, it delivers an estimated increase in uptime of 33%. Parts are reduced by 23% and labour costs reduced by 16%. The operational and cost benefits offered by


advanced solutions and technology make investment in bearing protection a common- sense decision.


AESSEAL www.aesseal.com/en DESIGN SOLUTIONS | MAY 2020 31


Properly functioning bearings are key to ensuring the efficient running of plant machinery. But without


appropriate maintenance they can also be one of the main causes of equipment malfunction and unscheduled downtime. Joshua Banks of AESSEAL explains how a proactive approach to bearing care can improve reliability and avoid unnecessary costs


Machine Sentry fixed on a pump


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