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The following article appeared in the February 2007 issue of Power Transmission Engineering. Bearings Product FocusQBC’s Ball-Less Ceramic Bearings Feature Lighter Weight The bearings are constructed of Zirconia–ZrO2 ceramic material, which resists deformation, can be operated at high temperatures, and has improved resistance to chemicals. Their anti-friction characteristics make the bearings suitable for use in powder, dust and muddy water environments at speeds up to 1,000 rpm. Zirconia is also nonmagnetic, serves as an effective electrical insulator, and has low thermal conductivity and high fracture toughness. These ceramic bearings are designed to fit shaft size diameters ranging from 4–30 mm. Outer ring bearing outside diameters range from 12–62 mm. For more information: AST Bearing Launches Tapered Roller Bearing Line According to the company’s press release, the tapered roller bearings are completely interchangeable with those of major bearing manufacturers. These bearings consist of four basic components: the cone (inner ring), the cup (outer ring), tapered rollers and a cage (roller retainer). The cone, cup and rollers carry the load, while the cage spaces and retains the rollers on the cone. The cone, rollers and cage are referred to as the cone assembly. Individual cup and cone components are available, as well as the complete assembly. AST Bearings plans to supply both through-hardened and case-hardened tapered roller bearings. Through-hardened bearings have a consistent hardness throughout the component, and case-hardened bearings have a surface hardening combined with a tough, flexible core. Case-hardened bearings will be supplied upon special request only. According to AST’s press release, the tapered roller bearings offer dimensional stability under heavy loads, long life performance in harsh and contaminated environments, and a durable steel cage. Tapered roller bearings are used for heavy-duty, moderate-speed applications. Typical applications include agriculture, construction and mining equipment, various axle systems, conveyance vehicles, gearboxes, engine motors and reducers. A variety of inch and metric sizes is available. The standard stock sizes are: ID 15–240mm (0.59–9.45") and OD 35–400mm (1.38–15.75"). For more information: SKF’s Ball Bearing Units Operate at Dynamic Load Capacity Unlike conventional set screw bearing units used in fans and blowers (which contact the shaft in only two or three places), ConCentra ball bearing units feature a patented multi-step sleeve arrangement. As the special mounting screws are tightened during installation, the bearing unit’s inner ring is driven up a series of inclined planes, compressing a sleeve around the shaft. The resulting secure and concentric fit delivers the optimized performance benefits. For removal, the mounting screws are loosened and dismounting screws tightened to reverse the process. This eliminates a need to cut bearings from shafting during removal. According to the company’s press release, the bearing unit’s concentric mounting technology creates a high locking force without requiring extremely close shaft tolerances. Shaft tolerances of ISO h9/IT5 can be used. Shafts also can be specified as commercial-grade or hollow to provide cost-effective alternatives to typically expensive ground, specially machined, or polished shafts normally mandated with set-screw air-handling units. The ConCentra ball bearing units incorporate SKF deep-groove ball bearings, either pre-lubricated for the life of the bearing (with special air-handling quality grease) or equipped with lubrication fittings. A two-part sealing arrangement consists of a low-friction contact seal and phosphated metallic flinger to prevent intrusion of solid and liquid contaminants, enhance grease retention, and minimize maintenance demands. Ball bearing units are available in pillow block and two- and four-bolt flange versions. Bore sizes (1" to 2-15/16") fit most standard fans and blowers. For more information: igus Bearings on Display at Pacific Design and Manufacturing Show Some of the new products on display will include: • Igus’ first linear actuator, DryLin ZLW, designed for compact, quick positioning of lightweight parts. • DryLinW compact linear guide system, now available with a stainless steel shaft for maintenance-free operation and optimal machine performance. • DryLin linear slide tables available in a variety of options to suit numerous requirements from compact, to fast-pitch to low-cost. • Compact igubal pivoting bearings to compensate for alignment errors. • Iglide plastic plain bearings, which are a replacement for bronze or re-circulating ball bearings. These bearings need no oil; they are self-lubricating and maintenance-free. Iglide plastic is also used in igubal, DryLin R and the gliding elements of all DryLin guide systems and tables. Therefore, igus’ entire line of machinery components is lubrication free. For more information: INA/FAG’s New Cylindrical Roller Bearing Increases Load-Carrying Capacity According to the company’s press release, the changes in surface quality have yielded an average improvement of 18% in dynamic load rating and an average increase in nominal rating life of 70%. Additional features include reduced peak roughness values on raceway surfaces providing optimized stress concentrations. INA/FAG offers two new cage designs—pressed-steel cage and profile-milled brass cage, in addition to the three traditional types of materials (polyamide, pressed steel and conventional machined press). The one-piece brass cage offers optimized roller contact on the cross piece, optimized roller retainment and minimized weight with necessary component strength. Applications involving strong vibration or high acceleration (such as gear/bearing arrangements) are most compatible with the one-piece, rib-guided solid brass cage. Bearings with a pressed-steel cage are usually suitable for applications requiring high temperature, good lubrication and high geometric stability of the cage. The X-Life pressed-steel cage is characterized by precisely defined guidance surfaces on the crosspieces, with which the rollers are in contact and therefore have precise parallelism to the crosspieces. In the old design, the guidance surface for the roller on the crosspiece was affected by the stamped surface and its poorer surface quality. The contact running surfaces of the new cage are both flat and uniform. For more information: Boca Bearing’s Ceramic Bearings Manufactured for Harsh Environments According to the company’s press release, ceramic is best suited for any application seeking to achieve higher rpm’s and to reduce overall weight for harsh environments with high temperatures and corrosive substances. Ceramic silicon nitride balls, for example, exhibit much greater hardness than steel balls, resulting in at least 10 times greater ball life due to ceramic’s ability to maintain the surface finish longer. The ball has dramatically smoother surface properties than the best steel ball, resulting in less friction between the balls and bearing race surfaces. Thermal properties are improved over steel balls, resulting in less heat build-up at high speeds. Ceramic has 35% less thermal expansion, 50% less thermal conductivity, and ceramic balls are lighter weight and non-corrosive. Boca also says the inner and outer races of anti-friction bearings become frosted, fluted or can get a corrugated pattern imprinted on them. These are not mechanical scars, but are in fact due to electromagnetic forces and can lead to bearing failure. They are usually found in modern systems that routinely feature pulse-modulated, adjustable-speed motors and inverters with high switching frequencies and short rise times. Ceramic hybrid bearings can replace the more traditional, chrome steel counterparts to eliminate scarring and run cooler due to less micro-weld adhesion. Boca Bearing Co. manufactures ceramic balls, ceramic-hybrid bearings and full-ceramic bearings for cry pumps, medical devices, semiconductors, machine tools, turbine flow meters, robotics and optics. For more information: LM76 Announces FDA- and USDA-Compliance The bearings are manufactured in inch sizes of 1/4"–1 1/2" and a profile rail-and-slide system that can be integrated into new and existing applications. Bearing options include self-lubricating Teflon composite bearings in a 304 stainless steel shell, and bearings with a ceramic-coated shell and FDA- and USDA-compliant liner. The bearings are available in closed and open configurations, and are drop-in replacements for inch-sized linear ball bearings. Shafting options include solid and hollow L 304 stainless steel and ceramic-coated aluminum shafts in lengths of 12'. For more information: MRC Bearing’s Customized Steel Bearings Perform Best in Harsh, Corrosive Environments Applications include food processing equipment, paper mill machinery and industrial pumps, among others. The presence of nitrogen coupled with high chromium in HNCR steel in these bearings contributed to improved corrosion resistance, compared with 440C stainless. According to the company’s press release, hardened and tempered HNCR provides hardness (58HRC) comparable to 52100 steel, and HNCR steel yields fatigue life better than 52100 to extend service life. For more information: Saint-Gobain’s Newest Bearing Material Offers Universal Chemical Inertness According to the company’s press release, Rulon® has a virtually universal chemical inertness. Of the chemicals encountered in commercial practice, only molten sodium and fluorine, at elevated temperatures and pressures, show any signs of attack. For continuous non-lubricated service, RULON® LR sleeve bearings are capable of operating up to 10,000 PV. Higher values are possible for intermittent service. For more information: |      | ||||
The new BCCRIXM Series of 28 ball-less ceramic bearings from Quality Bearings and Components features lighter weight and better shock absorption characteristics when compared with conventional types.
AST Bearings added a new product line of high-carbon, chromium-steel tapered roller bearings.
SKF’s ConCentra ball bearing units for high-speed air handling applications integrate concentric locking technology to form a near-360º interference fit with the shaft. This serves to reduce noise, vibration, and potential fretting corrosion; reduce risks of uneven load distribution, imbalance, and shaft damage; and enable units to run at their bearings' full dynamic load capacity.
igus Inc. plans to showcase iglide bearings® and DryLin® linear guide systems and other motion control technologies at the Pacific Design and Manufacturing Show.
The X-Life cylindrical roller bearings from INA/FAG were designed to increase load-carrying capacity and extend bearing life.
LM76’s new FDA- and USDA-compliant bearings were designed for applications involving processed food, packaged food, medical instruments, medical devices and pharmaceutical products.
MRC’s custom HNCR steel bearings are constructed from high-nitrogen corrosion-resistant steel, and they offer improved corrosion resistance and fatigue life compared with conventional stainless steel bearings. The company says these bearings perform best in harsh, corrosive environments.