Page 18 - Industrial Technology EXTRA 15th March 2021

EXTRA ‘FOCUS’ BEARINGS AND SLIDES

Miniature precision bearings meet the

needs of dental drill applications

n dental air turbines, miniature rolling
bearings must overcome a very demanding
set of challenges. As well as rotating at
Ispeeds of up to 500,000 rpm, these
bearings must provide extremely quiet operation
and meet rigorous hygiene requirements. NSK
offers precision miniature bearings made from
stainless steel especially for this application.
Driven pneumatically by a turbine wheel, the
two bearings in the head of the instrument
ensure stable guidance of the drill during dental
procedures. Miniature bearings, which have an
outer diameter of just 6.35 to 7 mm, need to increases corrosion resistance. The rolling
attain speeds of up to 500,000 rpm and stop elements of NSK’s miniature bearings for dental
very quickly. In addition, the bearings must avoid drills are made of high-performance ceramics,
the generation of micro-vibrations and tolerate while the cage material is either PEEK (a high-
frequent cleaning and sterilisation, usually with performance plastic) or Torlon PAI (a polyamide-
hot, moist air in an autoclave environment. imides thermoplastic).
For many years NSK has been developing All of the components used within these
and manufacturing precision miniature bearings miniature precision bearings achieve the highest
for dental air turbines. Historically, these levels of accuracy. This outcome applies equally
bearings were destined exclusively for the Asian to the reproducibility of the ball diameter as it
dental equipment market, but today also for does to the surface quality (roughness) of the
Europe. raceway, and the roundness of the raceway and
Among the materials used to make the cage.
bearings is ES1, a special stainless steel NSK also offers dental bearings in the highest
developed by NSK that provides significantly accuracy class ABEC9 (P2) while attaining a
increased purity and corrosion resistance bore diameter sorted tolerance class from
compared with the commonly selected AISI 0.0025 to 0.00125 mm, and from 0.00125 to
440C (equivalent to ISO 1.4125). The high 0 mm. The consequence: NSK bearings are
purity of ES1 stainless steel has a positive effect claimed to produce significantly less micro-
on bearing service life, since any inclusions or vibration and emit less noise than comparable
structure irregularities can cause stress cracks or bearings from other manufacturers.
flaking on the bearing raceway. Using ES1 also www.nskeurope.com

March 2021 • INDUSTRIAL TECHNOLOGY EXTRA • p18