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This issue of the National Precision newsletter brings you both a bit of history and a cautionary tale. We are working hard to both serve all your bearing needs and appreciate the warmer days of summer.

Dental Evolution

Have you ever visited the dentist's office hoping that you don't hear the dreaded words "root canal" or something to that effect? Like millions of Americans, you probably have had some kind of dental work done involving a dental hand-piece better known as a drill. Just the shrill sound of the drill makes a lot of people squeamish. We have it easy, however, compared to what our ancestors had to go through in the past.

The earliest evidence of dental drills being used comes from the Indus Valley Civilization back in 7000 BCE. These early dentists used a bow drill. A copper needle would be intertwined in the bowstring and the bow would be manually moved back and forth in a sawing motion to drill in to the tooth.

The first mechanical drills were made in 1864 and would spin at 15 rpm. In 1868, an American dentist, George Green, invented a pneumatic dental drill powered with pedal operated bellows.By 1875, electrical dental drills were developed and in 1914, these electrical drills could reach up to speeds of 3000 rpm.

Modern dentists use air turbine drills driven by compressed air. These drills can reach speeds of over 500,000 rpm. Most modern drills commonly work at the 400,000 rpm range for "high speed" applications while the others operate at 40,000 rpm for "slow speed" applications.

In the future, dental drills are being developed that use quick short laser pulses. These lasers drills can drill extremely small holes very quickly resulting in very little heat being absorbed by the sensitive areas of the tooth. Another alternative method being developed uses air abrasion, which operates similar to a mini sand blaster. So the next time you go to the dentist, be thankful of how good we've got it.

National Precision Bearing carries an extensive inventory of dental hand-piece replacement bearings manufactured in the USA by NHBB. Ask us about our new line of ceramic bearings for high-speed dental hand-pieces!

John Meneses, Miniature Product Manager

Have You Qualified Bearing Sources?

When sourcing products from China or other low cost countries there can be many issues and quality concerns to consider. More than a few stories have circulated recently on a variety of products such as toys, toothpaste, and milk that were sub-standard and potentially harmful to humans. There is also a high profile story related to sub-standard workmanship by a Chinese bearing factory.

On May 30, 2008, two men died when the welds on a large turntable (slewing ring) bearing failed causing the crane assembly to fall some 20 stories to the pavement below. The main bearing was repaired in China for substantially less cost than could be offered in the USA. Federal investigators later tied the accident to improperly welded repairs made a year earlier by the Chinese company. For on overview of the failure visit: http://www.nytimes.com/interactive/2008/05/30/nyregion/20080530_CRANE_GRAPHIC.html#

There are many very reputable and trusted Chinese bearing companies. However, there is reason to use caution when dealing with Chinese bearing products and the many new factories and sources showing up every day. Stories of counterfeit and sub-standard products continue to surface on a regular basis.

At NPB we strive to supply the appropriate product for each application. Our extensive experience with Chinese bearing products dating back to the 1980s gives us a unique perspective to help determine value and reliability of existing and new sources. Visit www.nationalprecision.com for a copy of our ISO/AS Certification. If you have questions about a product you have or want to import, please contact your NPB Technical Sales Specialist.

Bruce Dumas, Aircraft Product Manager

We hope you have enjoyed these articles and cracked a smile or two in appreciation for the improvements in modern dental science. We take quality very seriously and require the best of our suppliers. Please contact us with your concerns and questions.

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