Design News, April 2013

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Automation & Control A Comparison of Three Different Ball Bearing Materials Every manufacturer offers its own versions of ball bearings with varying features. By Tom miller, iguS B all bearings can be used in a variety of applications from medical and aerospace technology to packaging equipment, electronics, office technology, and even high-end yo-yo's. Since these components are available in different types of materials, each with its own set of features and benefits, weighing the pros and cons of a specific kind of ball bearing can become an important part of the design process. Three main types of ball bearings are steel, ceramic, and polymer. While every ball bearing is comprised of four main parts — an outer race, an inner race, a cage, and balls — each has its own set of characteristics and benefits. However, steel ball bearings do have some disadvantages. They are heavy, tend to deliver noisy operation and, depending on the grade of steel, lack chemical resistance. They require constant lubrication, which increases the time and cost spent on maintenance. Steel is also susceptible to corrosion in humid or wet environments and, specifically in medical applications, its magnetic properties can cause problems. In addition, there is such high number of steel ball bearing manufacturers that prices can greatly vary, ranging from downright inexpensive to very costly. This could be perceived as a pro or a con, but either way, the options can be overwhelming at times. Steel Ball Bearings Ceramic Ball Bearings SourCE: iguS Partly because they are an older technology, steel ball bearings are a trusted solution for many design engineers. Typically these types of bearings are comprised of all-steel parts, but are available with different types of steel races and balls, or with a phenolic cage. Steel ball bearings are ideal for robust applications handling extremely high loads and fast rotations per minute (RPMs), specifically when compared to polymer ball bearings, and some feature a radial load capacity of up to 30,000 lb. Another advantage is that steel ball bearings tend to be more precise due to the clearance that can be achieved. The most common type of ceramic ball bearing is often considered a "hybrid," which indicates the outer race, inner race, and cage of the bearing is comprised of steel, while the balls are made of ceramic. The ceramic material enables the bearing to run faster while maintaining a cooler operational temperature and simultaneously reducing noise and vibration. Ceramic ball bearings tend to be more corrosion-resistant, more rigid, and lighter weight than most steel ball bearings. Lower coefficients and higher RPMs are also possible and, since they are nonconductive, ceramic ball bearings can be xiros plastic ball bearings open new fields of application for plastic bearings. The inner and outer races are made from highperformance iglide materials. The corrosion-free balls are made from stainless steel. glass balls are also available for maximum corrosion resistance. S16 AUT O M AT I ON & C O N T R O L : A S U P P L E M E N T T O D E S I g N NE w S A p ril 2013 [www.designnews .com]

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