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knowing how to find the right combination THE TRANSFORMATION OF AN AGE-OLD COMPOUND CERAMIC’S COMPETITIVEADVANTAGES

Ceramic Bearings - 4918 For thousands of years, civilization has reliedon ceramics - thanks to their heat- and cor- rosion-resistant nature - for everything from dishes to ma- chine operations. Today, ce- ramics have evolved into ad- vanced industrial components.By integrating ceramic ballsand metallic races, including 440C, 52100, M50, BG42 and beryllium copper races, we have significantly reduced bearing wear and lubrication breakdown in high-speed components, such as dental hand pieces and turbine engines.Engineered ceramics are high technologyproducts manufactured with advanced pro- cessing equipment for critical applications. Some of these materials have been specially developed to withstand the high cyclic stresses and localized wear seen in bear- ings. Bearings have been attractive appli- cations for engineered ceramics because these materials are abrasive-resistant, heat resistant and can sustain large compressive loads, even at high temperatures.More than 20 years of research and testingprove that ceramic bearings:

Timken engineers have developed hundreds ofceramic designs. We continue to focus on solu-tions that incorporate the silicon nitride (Si

3

N

4

)family of ceramic compounds, known for their low-density, hardness, elasticity, tensile strength and other benefits.Silicon nitride’s density is 40 percent of traditionalbearing steels. Because force is directly propor- tional to mass, the lower-density silicon nitride significantly reduces the centrifugal forces of the balls on the outer ring. This enhances operations in high-speed applications where outer race contact loads may hinder performance.Bearing life is directly related to hardness, themost critical mechanical property of a bearing material. With an impressive Rockwell C 78 hard- ness - twice as hard as many bearing steels -silicon nitride improves wear resistance, minimizingthe damaging effects of repetitive surface contacts.In high-speed applications, bearings mustwithstand extremely high temperatures.Timken ceramic bearings operate preciselyat temperatures up to 1,800ºF for extendedperiods, compared to short-term maxi-mum temperatures of 1,000ºF for the besthigh-temperature bearing steels.In hybrid ceramic bearings, the surface as-perities of steel races and ceramic rolling ele- ments do not micro-weld, preventing or slowing failure caused by adhesive wear, fretting wearand/or lubricant breakdown.Three other silicon nitride characteristics enhancebearing performance in some applications, suchas corrosive or electrical environments: It is vir-tually chemically inert, it is non-magnetic and it does not conduct electricity.

INCORPORATINGCERAMIC HYBRIDS INTOYOUR APPLICATIONS The lower-density sili-con nitride significantly reduces the centrifugal forces of the balls on the outer ring.

In applications where heat, friction, speed, adhe-sive wear and marginal lubrication are factors, Timken hybrid bearings may perform significantlybetter than steel bearings. Our hybrid bearingscurrently operate in: Gimbals; Aircraft accessories; Medical hand pieces; Can-seaming machinery; and Food-processing equipment.Hybrid bearings in turbo molecular pumps reducenoise, vibration, and operating temperatures, aswell as increase life, and allow for operation under marginal lubrication conditions. The cooler opera- tion of the ceramic hybrid permits the use of grease in place of oil previously used in conventional allsteel bearings.In corrosive atmospheres - including pumps,meters and semiconductor applications -

Bearings have been attractive applications forengineered ceramics because of these mate-rials’ overall superior quality. Ceramic bearings con-tinue to grow in popular-ity. Timken ceramic bear-ing customers report enhanced performance,reliability and bearing lifewith our designs.

Maintain longer, more reliable performance;Reduce noise and vibration;Retain stiffness;Operate at lower temperatures; andRequire less lubrication. Timken

®

ceramic bearings reduce wearand extend life.

continuing to develop solutionscontinuing to develop solutionsunderstanding the elementsunderstanding the elements