In the search to maximise engineering efficiency at every possible level, energy efficient bearings offer a powerful cost-saving alternative, with or without upgrading your motors, says Phil Burge, communication manager for SKF
In the on-going global recession, the focus of most engineering companies remains on protecting operating margins, with little scope to increase prices. The options, however, are limited as raw material and energy prices continue at high levels, and meeting the tougher environmental legislation adds to the cost.
Energy is one of the highest costs for many businesses, so anything that can be done to reduce consumption will have a significant impact on the bottom line. In particular, electric motors account for up to 66% of all factory energy costs – estimates vary, but most analysts put the figure at 50% plus. While the simple solution would be to replace older motors with modern high efficiency equivalents, this is rarely an option when cash flow or capex budgets are tight.
An alternative is to replace the bearing units in existing motors with energy efficient versions, which are capable of cutting energy wastage by up to 50%. These units can be exchanged during routine maintenance, so there’s no additional downtime cost, and can also help to extend the operating life of the average motor.
Today’s leading energy efficient bearings enable components to rotate more easily with minimum friction and heat, dramatically reducing wear and enhancing performance. For example, E2, a range of energy efficient deep groove ball bearings from SKF, feature technical innovations that reduce friction. The internal geometry of the bearings has been optimised via the use of advanced modelling tools which, in tandem with a new, fit-for-purpose polymer bearing cage, has brought a marked improvement in operating efficiency. The company has also formulated a low friction grease, which reduces still further the energy losses between the rolling elements and the rolling element lands.
Depending on operating conditions, energy efficient bearings can save at least 30% of frictional moment compared with standard bearings and in some applications 50% or more, while operating temperatures can be up to 30°C cooler, depending on speed. This improved performance also provides additional benefits, including longer grease life and extended re-lubrication intervals, further reducing maintenance and running costs.
The latest bearings are generally suitable for use in electric motors of up to 37kW in size, as well as 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 3,000rpm, they will typically deliver energy savings of 270kW per year. In practice, the efficiency offered by these bearings improves as motor speed increases, providing the potential for even larger savings in applications that require higher shaft speeds. In addition to saving money, the potential of energy efficient bearings to reduce the environmental impact of industrial applications meets the demands of the increasingly tougher environmental legislation that is put in place to combat the effects of global warming. For example, the 37kW motor in the estimate above not only delivers significant energy savings but also keeps more than 150kg of CO2 out of the atmosphere.
Perhaps most importantly, these bearing units are dimensionally interchangeable with ISO standard components, meaning that they can be exchanged during routine maintenance, while their longer service life enables the operating life of the average motor to be extended, translating to further savings in the cost of ownership. For example, when GlaxoSmithKline Consumer Healthcare introduced
SKF E2 bearings to a cold water pump motor, they achieved a return on investment in just 17 days. Utilised in 22kW motors running at 2,990rpm, the bearings were able to deliver savings of 0.56kW per hour, which resulted in an annual energy saving of 4,583 kWh per motor. At today’s electricity rates this amounts to an approximate saving of £600 per motor.
As energy continues to become an increasingly precious and therefore expensive resource, there has never been a more appropriate time to reduce the energy required by plant and machinery across all sectors. To this end, the designers and engineers behind today’s bearing technology are enabling customers to apply significant efficiency gains to the running of motors even without the cost of replacing them.
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