But without appropriate maintenance bearings can also be one of the main causes of pump malfunction and unscheduled downtime. Joshua Banks, of AESSEAL, explains the importance of taking a proactive approach to bearing care to improve reliability and avoid unnecessary costs.

Bearings have a vital function in the efficient functioning of pumps but they are also one of the key causes of pump breakdown, leading to costly downtime for repairs and replacement. 

There are a number of reasons why bearings fail, but chief among them are particle contamination, inadequate lubrication and misalignment. 

These three issues collectively cause almost three quarters of all bearing failures. Yet this could be reduced significantly, simply by making judicious decisions about the maintenance approaches and sealing solutions employed.

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.

To give an indication of the impact even the smallest amount of contamination can have, research indicates that water contamination as low as 0.002% - that’s equivalent to a single drop of water in a typical bearings chamber - can reduce bearing life in some oils by as much as 48%. 

In another example - an oil-lubricated 45 mm 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 - a dramatic decrease in mean time between failure (MTBF).

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.

Lubrication

Lubrication is often the ‘poor relation’ of a condition based maintenance (CBM) programme, treated as an afterthought, lumped in with other maintenance activities or, worse, not planned at all. 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, and as such routine testing and analysis should be a fundamental part of any regular CBM programme. 

Misalignment

According to design requirements, machine components are typically coincident, parallel or perpendicular during operation. Any 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 becomes ever more apparent.

Technology for reliability

Bearing failure is so common that some engineers see it simply as a necessary evil to be factored into ongoing maintenance. Downtime is accepted as part of this process.

However, advanced technology presents the opportunity to make a seismic shift away from a costly reactive maintenance approach.

The single most common cause of bearing failure – contamination of the lubrication oil – can be all but eliminated by installing labyrinth-design bearing protector seals which prevent the ingress of dust or moisture into the bearing chamber. These replace commonly applied lip seals.

These incorporate dynamic lift technology to facilitate the ‘breathing cycle’ required by rotating equipment, while preventing the ingress of contaminants. The centrifugal force of rotating equipment is employed 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.

The seals’ integral shut-off O-ring is made from a highly resilient elastomer material, which exhibits near-zero wear. 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, upgrading to a more efficient synthetic bearing lubrication oil becomes less a risky investment and more a common sense measure to optimise efficiency.

Cloud based CBM

Advanced cloud-based technology such as AVT Reliability’s Machine Sentry™ has created an opportunity to introduce genuinely 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, which can be collected and consolidated on one platform from multiple locations, where it can be securely accessed from anywhere 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 presents up to four potential points of failure, ranked in order of likelihood, and 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 of in-depth knowledge on which to base 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. 

Cost will understandably be a consideration for companies looking to secure a swift return on investment. They should note that this technology has become cheaper, even as its capabilities have become more sophisticated. It is scalable to any industrial plant and any maintenance team can use it, regardless of qualification. 

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%. 

These operational and cost benefits offered by advanced solutions and technology make a compelling case for any company looking to improve reliability and improve the bottom line.

For more information visit:
www.aesseal.com