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By Sheila Kennedy, Contributing Editor
Bearing manufacturers are altering their designs, materials and manufacturing methods in a quest to improve noise, friction, size, energy efficiency, environmental friendliness and maintainability qualities.
Noise and friction: Schaeffler Group’s FAG Generation C deep-groove ball bearings generate half the noise and one-third the friction of its predecessor bearing. The new design allows applications to operate more quietly with increased efficiency and higher speeds, with a longer operating life.
The noise level reduction comes from the bearing’s reworked internal design. Improving the manufacturing methods reduced internal friction to decrease energy consumption and costs. The raceway surfaces are smoother, the balls are high-quality, and the osculation between the balls and rings is optimized. A riveted steel cage is standard, providing greater rigidity and reduced sensitivity to shock loads. The bearings are lubricated for life using high-quality grease.
In addition, Generation C deep-groove ball bearings have an HRS lip seal made of nitrile butadiene rubber rather than the previous RSR seal. HRS sealing keeps contamination and moisture out of the bearing and keeps the grease inside. It generates less friction and heat at high speeds than RSR, and the sealing action is more effective.
Micro-scale: Miniaturized ball bearings are being used in fast, reliable and robust micromachines. Researchers at the A. James Clark School of Engineering, with funding from the U.S. Army Research Laboratory and Research Office, developed miniaturized ball bearing support mechanisms for the nearly invisible microballs that are the width of a few human hairs. Using these components, the research team manufactured micromachines, including miniature silicon pumps, motors and turbines. The researchers demonstrated rotational speeds of 87,000 rpm, which is comparable to large-scale machinery speed.
Microbearings are integrated into micro-scale liquid-fuel power generation systems, which significantly reduce the battery load of soldiers in the field. A second application being developed involves silicon microgenerators supported on microball bearings to help power the electrical systems of land- and air-based micro-vehicles.
Energy efficient: SKF has developed new energy-efficient spherical and cylindrical roller bearings and will begin manufacturing them during the second quarter of 2009. The energy-efficient, spherical roller bearings exhibit at least 30% less friction, lower energy consumption and reduced bearing temperature, and can extend grease life and relubrication intervals. Industrial ventilation fan applications will be the initial target for this technology.
The SKF NJ series of energy-efficient cylindrical roller bearings produce 30% less friction in axially loaded applications than the SKF standard NJ series bearing, and they have a higher dynamic load rating. The first applications will be industrial and wind energy transmissions. Other applications will follow.
Eco-friendly: igus is touting several environmentally friendly properties of plastic compared to metallic plain and rolling bearings. The company’s tribologically optimized iglide plastic plain bearings are lubricant-free, so less oil and grease is released into the environment. High chemical resistance is inherent in the plastic bearings, whereas metal bearings are usually coated with energy-intensive galvanizing to achieve chemical resistance. The production of plastic consumes significantly less energy from oil than aluminum or steel, and the bearing’s light weight helps to reduce vehicle fuel consumption and carbon dioxide output.
Plastic bearings are suited for a variety of applications. To assist engineers with bearing selection, igus offers free, 24-hour access to its Expert System database, which estimates the life expectancies and performance patterns of its plastic bearings based on given application variables.
Self-lubricating: Lubrication-free bearings provide generous maintenance cost savings. Rino Industries introduced a range of self-lubricating linear bearings. The closed and open bearings are manufactured from a Teflon composite liner bonded to an aluminum shell. Bore sizes range from 5 mm to 80 mm.
Rino’s DU bushings are dry, cylindrical, compact, lightweight bearings that require no lubrication. Manufactured from steel, the dry bearings have a low wear rate and high static and dynamic load capability. Other characteristics include good frictional properties, resistance to solvents, tolerance of dusty environments and electrical conductivity.
SKF recently introduced ConCentra relubrication-free roller bearing units for industrial fans used in air-handling equipment. The new units can be combined with the SKF ConCentra ball bearing units for a complete, relubrication-free fan shaft support solution. The patented SKF units are pre-greased and feature integral seals for further protection from contaminants.
E-mail Contributing Editor Sheila Kennedy, managing director of Additive Communications, at Sheila@addcomm.com.
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