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Southern Manufacturing

Farnborough, Hants(GU14 6TQ)

20/04/2021 - 22/04/2021

Southern Manufacturing and Electronics is the most comprehensive annual industrial exhibition in the (more)

PPMA Show 2021

NEC, Birmingham(B40 1NT)

28/09/2021 - 30/09/2021

PPMA Show 2021 will be the UK’s largest ever event dedicated to state-of-the-art processing and (more)

Advanced Engineering 2021

NEC Birmingham(B40 1NT)

03/11/2021 - 04/11/2021

Join us in our 12th and most important edition to date, as we invite engineers and management from all (more)

A roll for improved efficiency

A roll for improved efficiency
Small changes may be as important as grand gestures when it comes to improving energy efficiency. New rolling element bearing designs, for example, can reduce friction in motors and machines by up to 30 percent, says SKF's Phil Burge

Energy efficiency is climbing the agenda for governments, companies and consumers. Whether they are motivated by tightening regulation, the desire to reduce carbon dioxide emissions and the environmental impact of their operations, or by the need to protect themselves from exposure to increasingly volatile energy prices, many companies are now taking a long, hard look at the way they obtain and use energy.

The impact of industrial activities on global CO2 emissions has been particularly newsworthy in recent months, further sharpening the focus on energy use. Industrial activities are important energy consumers - around one third of the world's electricity is used in industrial processes - and as a result, there is increasing pressure to reduce the amount of CO2 generated. 

There are many possible approaches to reducing the carbon intensity of industrial production. Companies may switch to different sources of energy, like wind, hydroelectric or nuclear power. In the future, they may also be able to use 'clean' fossil fuel sources that capture and store their CO2 emissions underground.  Alternatively, they may 'offset' emissions from existing energy sources by investing in projects that reduce CO2 production elsewhere in the global economy.

The quickest way to cut emissions, however, is to consume less energy in the first place. Energy efficiency improvements have many advantages - not least because they can actually save money. While some big leaps forward in energy efficiency may come from large switches in technology, the majority will emerge from much smaller changes in the way equipment is designed, built and operated. Electric motors are a compelling example of the way detail can have a big impact in improving efficiency. Worldwide, two thirds of the electricity consumed by industry is used in electric motors. Companies can make several relatively low cost changes to dramatically reduce the amount of energy their motors consume. Choosing efficient models and ensuring that motors are correctly sized for their application are great first steps, as the installation of variable speed drives to better match energy use to varying loads and speeds. Increasingly, equipment designers and operators can also select components that offer significant efficiency advantages.

When we developed the SKF Explorer range of rolling element bearings our engineers made use of advances in bearing design and analysis techniques, and in material production and treatment technology to produce a class of bearings that could offer large improvements in load carrying capacity and life compared with the ISO standards. Two years ago, we launched a project to apply the same techniques to a new goal: the development of a highly efficient, low friction bearing design that reduces frictional losses in electric motors and rotating machinery. The result is the SKF E2 Energy Efficient deep groove ball bearing design.

Minimising friction
These bearings incorporate a host of technological changes to minimise friction in use. Thanks to the strength and reliability of modern bearing materials, the number of rolling elements has been reduced. The bearings rotate in a cage that is both lighter and less prone to distortion, when compared to standard designs. Made with the help of a suite of proprietary bearing simulation tools, detailed changes to contact surface topography and internal geometry improve the performance of the lubricant film inside the bearings. Finally, a special, low-friction grease has been developed alongside the bearings. When used as a system, the E2 bearings and this new grease reduce friction by at least 30 percent - and as much as 50 percent - compared to standard bearings.

The latest bearings are suitable drop-in replacements for products in electric motors up to 37kW in size, and for other rotating machinery applications with shaft diameters of up to 60mm. If E2 bearings are used in a single 37kW motor, running continuously at 3,000 rpm, they will deliver energy savings of 270kWh per year, keeping more than 150kg of CO2 out of the atmosphere. In practice, the efficiency improvement offered by these bearings goes up as motor speed increases, offering the potential for even larger savings in applications requiring higher shaft speeds. 

Improving bearing efficiency has other advantages too. Reduced friction means less noise and vibration, and leads to lower operating temperatures too. In tests, the latest bearings typically run 8-10°C cooler than standard bearings. The low friction grease used in the bearing has twice the life of standard bearing grease, extending maintenance intervals and further reducing cost of ownership; indeed, this new bearing technology will offer twice the service life suggested in the ISO equations. 

This latest bearing technology is just one example of a philosophy of incremental improvements in the quest for improved efficiency. Elsewhere, we have worked with a leading compressor manufacturer to install magnetic bearings on a 12MW compressor at a natural gas storage facility, saving around 70,000kWh per year. Similarly, an effective programme of condition monitoring can play an important role in helping engineers keep production processes operating as efficiently as possible, by alerting them to wear and damage that would otherwise increase energy demand, affect quality or disrupt production.

Changing the bearings in an electric motor might seem a small gesture, but ultimately millions of small gestures have the potential to deliver giant leaps in efficiency. If every industrial motor currently turning in the US and the EU was fitted with high efficiency bearings, for example, the combined saving in energy would be an astonishing 2.46 billion kWh every year.
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