Design News, May 2013

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from a 300 series stainless steel. In high-speed applications, it is often necessary to use a plastic or phenolic resin "snap-in," or crown, style retainer. For very high speeds, an angular contact bearing with a full-machined retainer is recommended. Phenolic resin cages have a porous structure and can be impregnated with oil for additional lubricity. Some of the plastic materials, such as polyamide-imides, contain additives such as graphite and Teflon for additional lubricity in emergency running conditions. A wide array of lightweight plastic materials are available, which can handle temperatures up to 500F and are autoclavable. An autoclave is a device used to sterilize surgical tools, dental drills, or other devices by subjecting them to high-pressure saturated steam for around 20 to 30 minutes depending on the size of the load. This is a common practice that can have a negative impact on the bearing materials and lubrication. Surgical and Dental Tools Some of the more demanding medical applications include ANOTHER LEE INNOVATION Lubrication Lubricant selection may be the specification most overlooked by designers and engineers. Bearing life depends on proper lubrication in terms of both type and amount. In many cases, miniature and smaller instrument bearings are lubricated once for the lifetime of the device. Thousands of greases and oils are available that are designed to function in a variety of conditions and environments. Operating temperature is the primary consideration when selecting a lubricant. Temperature directly impacts the base oil's viscosity, which in turn impacts the ability to support loads. In the world of medical devices, bearing lubricants are subjected to sterilization, temperature extremes, high-speed rotation, saline wash down or irrigation, chemicals, and reagents, blood, and radiation. Lubricant selection not only depends on the operating conditions the bearing will face, but may also be subject to regulatory requirements. Manufacturers of medical devices are often required to use what are known as food-grade lubricants. H1 lubricants are food-grade lubricants used in food processing environments where there is some possibility of incidental food contact. H2 lubricants are used on equipment and machine parts in locations where there is no possibility that the lubricant or lubricated surface contact food. H3 lubricants, also known as soluble or edible oil, are used to clean and prevent rust on hooks, trolleys, and similar equipment. Smallest Check Valve . . . Ever! s s s s s s MM $IAMETER ,OW ,EAKAGE !CCURATE #RACKING 0RESSURE )NSTALLS %ASILY IN 0LASTICS !VAILABLE IN -EDICAL &ITTINGS 0ERFORMANCE 4ESTED To Get Samples and See for Yourself, Contact The Lee Company! The Lee Company 0ETTIPAUG 2OAD 7ESTBROOK #4 53! 4EL See us at MD&M East, Booth #3234 [w ww. d e s ig n n e w s . c o m] magenta cyan yellow black MAY 2013 TR E ND WAT CH : ME DICAL / A S UP P LE ME NT TO DE S IG N NEWS T15 ES245812_DNTW1305_T15.pgs 05.03.2013 03:11 UBM

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