Company insight
The benefits of polymeric bearings and radial seals
We speak with Andrew Dearden, business development manager, and Gareth Holt, sales director, to learn about how industrial sealing provider Beldam Crossley is stepping into the wind turbine market, and the benefits its products can offer.
What are the main factors that cause wind turbine bearings to fail?
Andrew Dearden: With metallic bearings, axial cracks can in the existing bearings, which leads to bearing failure. Another factor that can cause failure in a metallic wind bearing is lubrication contamination. This results in a change in the viscosity and causes the bearing to then run hot. Our approach to prevent bearing failure is to provide a solution that works – though, of course, lubricant isn’t required with most polymer-based seals, especially PTFE.
What are the benefits of Beldam Crossley’s Crossflon material in this setting? AD: Crossflon is our brand of PTFE solutions – we have very different grades depending on application, and we work with the client to ensure the correct material is specified or developed. Because it’s a polymer, bearing failures due to lubrication contamination issues are eliminated as PTFE is self- lubricating. The other benefit of Crossflon material is that is has excellent chemical compatibility with a wide range of media. PTFE’s high load-bearing capacity, in conjunction with a low coefficient of friction in comparison to most metallics, makes it an outstanding choice for radial bearings. A metallic can have a very high coefficient of friction – if you try dragging something over metal, performance will be greatly affected unless it’s lubricated. Gareth Holt: On 2.5mm PTFE sheets, the biggest platform that we’ve skidded […] is in excess of 50,000t. With a metallic bearing […] the higher the load, the greater the friction. And as
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the friction builds the temperature builds too, which causes wear to increase. PTFE is completely the opposite. By loading the material appropriately, you can reduce the friction, which means less wear on the turbine, on the shafts and on the gearbox.
What are high-performance polymeric radial seals? AD: Radial shaft seals are mounted between the rotating and stationary components, or two components in relative motion. The seal can take on many profiles but typically they consist of an outer cylindrical circumference with an interference fit that seals statically against the housing bore. The inner sealing lip seals dynamically and statically against the shaft. It’s sealing edge presses against the counter face surface of the shaft. Radial seals are commonly used in cap and plug, piston and bore type applications.
What are the benefits of PTFE high-performance radial seals, and how do they help to extend bearing life within wind turbines? AD: When we talk about the benefits of PTFE and how we extend the bearing life, there’s an increased reliability of the overall system, especially with spring energised seals due to reduced leakage rates. We see improved performance in a wider scope of weather conditions and high and low temperatures due to the thermal stability of PTFE. This results in easier adaptability to a wider range of sizes, especially with tape bearings. There’s also reduced cost from less maintenance –
depending on the application, PTFE can be a lot cheaper than metallic seals. And the self-lubricating nature of PTFE can make the material “other lubricant free”.
How does Beldam Crossley bring a fresh perspective to the market? AD: Over the past few years, across the UK and in Europe, there’s been massive supply chain issues, and increasing costs within materials and within metallics in particular. This has been generated by a number of factors that no business could have foreseen – Covid-19 and its variants, the Suez Canal obstruction, and the invasion of Ukraine by Russia. So, businesses find themselves having to re-evaluate the supply chain across the board. […] As a smaller organisation compared to our competition, it allows us greater flexibility – we can make driven and decisive decisions promptly, whether this means priority reorganisation of our production schedules and manufacturing cells, or even additional CapEx spend on new machinery. We can fulfil demand from one-offs right through to mass production – our competition can’t do that. GH: Wind turbines have been around for 25 years. And back then, the very, very big players got involved in the supply of products. Now, as there’s massive push to green energy, there’s also a push to having a more efficient system that will perform over a longer period of time. […] And at the minute, the two or three key manufacturers of sealing technology are seen as the only options. We’re saying there is an alternative. ●
www.beldamcrossley.co.uk World Wind Technology /
www.worldwind-technology.com
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