14/06/2022 SMB Bearings Ltd
It is estimated that a 10% reduction in friction in all large bearings used would provide an energy saving equal to the output of 18 large power stations. Reducing friction in bearings of any size is a key method of improving energy efficiency. Here, Chris Johnson, general manager of miniature bearing supplier SMB Bearings, explores the possibilities of bearing design for increased efficiency in industrial applications.
In recent years, bearing manufacturers have increasingly focused on creating energy efficient bearings – using new materials, lubrication techniques and advanced geometric designs to reduce losses without sacrificing load carrying capacity.
However, energy losses in the bearings are not considered the primary focus of plant optimization as they are already considered a high-efficiency component. However, some argue that bearings are so ubiquitous that potential energy savings should not be ignored. Let’s take a closer look at three bearing design considerations for increasing efficiency.
Energy-efficient bearing designs primarily focus on reducing contact between the rolling elements and the raceways or cage. By reducing the roughness of the elements in contact, the friction will be reduced.
According to a 2021 study, friction-optimized designs can have a significant impact on reducing overall bearing energy losses. Based on a bearing manufacturer’s design, a preliminary estimate of this reduction is around 0.15-0.20% of global energy consumption.
Traditionally, steel has been the material of choice in bearing design, but polymer-based materials, such as PTFE and nylon, offer many advantages when used in less demanding environments. These benefits include corrosion resistance, reduced need for lubrication and reduced weight.
Geometric considerations such as special cage designs and the number of balls in a bearing influence the amount of friction. The geometry and the manufacturing process of the cage have an influence on the friction generated. For example, opting for a 3D printed carrier made of nylon (PA66) or another polymeric material can help reduce the weight of the entire bearing.
Carbon fiber reinforced nylon is one of the most popular combinations. It offers many of the same benefits as the standard, but produces significantly lighter components. Surface coatings can have a significant effect on reducing bearing friction. Coatings such as molybdenum disulfide and tungsten disulfide increase wear resistance, fatigue durability and reduce friction during bearing motion.
A proper lubricant will reduce friction between bearing components and reduce
metal-to-metal contact of the rolling elements. While this is a good way to reduce wear, there are new materials that significantly reduce friction compared to options currently on the market. The material in question is graphene.
The process of adding a graphene coating to bearings would be similar to adding a traditional lubricant. When graphene becomes readily available, we will take a closer look at this form of lubrication.
In addition to not being harmful to the environment, graphene flakes added to the surface of a bearing can last a considerable amount of time and provide a very low coefficient of friction (COF).
In a study of graphene’s potential as a lubricant, researchers estimated that the reduction in frictional energy loss offered by new materials would result in potential energy savings of 2.46 billion kilowatt hours per year, equivalent to 1.5 million barrels of oil.
By optimizing each element of a bearing design to account for friction, bearing friction can be reduced. By multiplying this saving for each bearing in a machine, plant or industry, significant energy savings can be achieved.
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