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Products
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Silicon Nitride (Si3N4) Balls are
used by World Leaders in the field of |
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Machine Tools : Spindle bearings,
Ball Screws. |
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Spindles mfg. by GMN Spindles USA run
at 42000 rpm, (11 kW) with power ranging upto 80kW by using Si3N4
balls. |
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Fuel Systems : Relief Valve applications
: Siemens VDO Automotive |
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Electric Motors |
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Pumps |
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Ball Screws from Umbra Cuscinetti, Italy handle
load of 1800 KN, axial speeds to 160m/min and acceleration capacity
to 3g. They use Silicon Nitride Balls
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Injection Molding machines: Electromechanically
operated by Ball screw and Electric Drive motors. |
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Spindles in Textile Industry where atmosphere
is moist always, Majority of Textile Industries in Europe &
USA use Silicon Nitride Balls for Spindles
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"When used to check certain soft materials
like Aluminium, Cast Iron, ruby balls tend to accumulate small bits
on their surface, rapidly leading to errors in measurements. When
used in scanning applications, ruby balls are susceptible to wear,
particularly on abrasive surfaces. Silicon Nitride Balls exhibits
no tendency to accumulate material and better abrasive resistance.
Scanning CMM users report up to 5 times longer tool life with Silicon
Nitride Balls than ruby balls." Mr. Tom Breth, Q-Mark CMM Accessories.
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"We've had great results from your
silicon nitride probes." - S. Schanhals |
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Eaton/Saginaw, Saginaw MI |
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The leaders use it because Silicon
Nitride Balls have following properties. |
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It overcome heat, reduce vibration
levels and Wear problems |
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Smooth and over 1 G acceleration
capacity |
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Can be operated at 30% higher
speed than that of steel balls |
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Enhances life by 100% or more |
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Improved Rigidity and Accuracy |
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Ultra Smooth surface and Chemical
inertness |
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Lower thermal expansion 2.9 x
10 (-6). |
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Maximum use temperature 1000 deg
C |
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Very High compressive Strength
3000 CPA |
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High Hardness > 78 HRC |
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Lowest Density 3.2 g/cc |
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High Young's Modules 320 Gpa |
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Excellent Corrosion Resistance |
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Completely Non-Magnetic and Insulator |
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Ball Fatique life > 100X |
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What the experts say. |
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" Using Silicon Nitride Balls in place
of Steel Balls cuts adhesion, boosts load capacity and reliability
and extends ball-screw lifetime" Mr. Luciano Pizzoni, Analyst
and R & D Chief Engineer, Umbra Cuscinetti.
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" The use of Silicon Nitride Balls has rapidly
increased due to the properties and we will add the specifications
in the standards. The specification is being developed within committee
ASTM F34.
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Mr. Jeff Wickwire, Quality Assurance
Representative, DCM Buffalo, New York. |
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" They are expensive but it pays more. In
our Relief Valve application, the ball sits on a seat in the assembly
and we coin the seat with the same Silicon Nitride Ball" Mr.
Harry - Product Engineer, Fuel Delivery Components Group, Seimens
VDO Automotive, Virginia.
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"I put the silicon nitride styli through the
paces. Previously, I wore a flat spot on two ruby probes. I'm still
using the silicon nitride styli. I can see no wear, even under magnification.
I plan to order silicon nitride tips as standard. Thank you for
introducing me to them." - T. Sutorous, Pacific Quartz, Santa
Ana CA
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Typical Applications of Silicon Nitride
Balls |
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Machine Tool Spindles |
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Turbochargers |
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Hard Disk Drive Spindles |
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Dental Handpieces |
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Textile Spindles |
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Ball Screws |
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Air Driven Power Tools |
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Surgical Handpieces |
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Semiconductor Processing Eqpt. |
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Turbo Molecular Pumps |
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Liquid Molecular Pumps |
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Flow & Gas Meters |
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Clean Environment (Low Particulate
Emissions) |
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Semi-Conductor Processing Equipment |
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Computer Hard Disk |
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Production Machinery |
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LCD Panel Production Machinery |
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Film Manufacturing Machinery |
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Food Processing Eqpt |
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Chemical Processing Eqpt |
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Sucker Rod Pump Check Balls. |
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In-Line Skates |
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Aerospace Instruments |
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Robotics |
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Liquid Oxygen Pumps |
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Kin Cars |
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Ovens & Metal Processing Eqpt. |
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Turbo Molecular Pumps |
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Semiconductor Processing Eqpt. |
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Scanner |
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Robitics |
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Hard Disk Drive Actuators |
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Contamination & Wear Resistance |
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Electric Motors |
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Paper Processing Eqpt. |
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Air Driven Power Tools. |
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Electrical Resistance/Nonmagnetic |
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Electric Motors |
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Paper Processing Eqpt. |
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System Rigidity and Accuracy |
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Kinematic Mounts |
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Machine Tool Ball Screws |
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HDD Spindles |
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Our Principles are the largest supplier of silicon
nitride balls to the Europe & American precision industry. The
TSN-03NH grade silicon nitride is considered by the bearing industry
to be an industry standard due to its high level of performance
and quality, a standard to which other silicon nitride materials
aspire
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Credits: NASA ©Aris Multimedia Entertainment,
Inc. 1991-3.
This material is used by the largest bearing companies in
the world, including FAG, Barden, SKF, and Koyo Seiko. It
is the only material to be approved for use in ball and roller
bearings in NASA's space shuttle main engine high pressure
liquid oxygen and liquid hydrogen turbopumps - one of the
most severe applications ever developed for rolling element
bearings. TSN-03NH is certified to meet ASTM F2094 Class I
requirements, the highest industry classification for silicon
nitride bearing materials. It also helped the Thrust SSC car
achieve its record-breaking Mach 1+ land speed run by allowing
the wheel bearings to operate reliably at over 480,000 dN.
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More "down-to-earth" applications
include bearings for: |
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Machine tool spindles |
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Computer hard disk
drives |
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Turbomolecular vacuum
pumps |
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High performance bicycles
and inline skates |
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Aircraft APU's and
starter motor/generators |
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Food processing equipment |
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Silicon nitride balls have also been used extensively
as check balls in high pressure or corrosive fluid systems. Most
major diesel fuel systems manufacturers are using silicon nitride
check balls today. The light weight, lack of adhesive wear, and
corrosion resistance of this material results in less wear of both
the ball and the check-valve seat, thereby reducing leakage.
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Key Properties |
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Applications exploit the following properties
of silicon nitride: |
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low density |
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high temperature strength |
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superior thermal shock resistance |
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excellent wear resistance |
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good fracture toughness |
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mechanical fatigue and creep resistance |
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good oxidation resistance |
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Bearings |
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The wear resistance, low friction and high stiffness
of fully dense silicon nitride improve the performance of high temperature
unlubricated roller and ball bearings. HPSN bearings have shown
increased bearing life, better speed capability and greater corrosion
resistance compared to conventional higher-density steel and hard
metal bearings.
The vast majority of silicon nitride bearings are
used in hybrid ball bearings (bearings with ceramic balls and steel
races). Applications include machine tool spindles, vacuum pumps
and sterilisable and unlubricated dental drills.
All ceramic bearings are used in applications where
corrosion, electric or magnetic fields prohibit the use of metals.
For example in tidal flow meters where seawater attack is a problem
or electric field seekers.
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Industrial Applications |
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Pertaining to Trailing
Edge Flap Ball Screw Assemblies For Use on Boeing Model 737-100, -200,
-300, -400, and -500 Airplanes |
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Subject: Thomson Saginaw Ball Screw Company,
LLC ("Thomson Saginaw") Ball Screw Assemblies for Usage
on Boeing Model 737-100,-200,-300,-400, and -500 Airplane Trailing
Edge Flaps
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Reference: Boeing Service Letter
737-SL-27-108 (ATA:2754-40) dated 21 May 1996 |
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Summary: Thomson Saginaw is the original
designer and manufacturer of trailing edge flap ball screw assemblies
for the Boeing Model 737 airplane, and has been designing and manufacturing
flight control ball screw assemblies for over 50 years. Accordingly,
the following information is being provided to users of the subject
ball screw assemblies in order that an informed decision can be
made when specifying ball screws for 1) new aircraft, and 2) service
requirements.
The reference service letter contains commentary on several technical
issues that require additional explanation, some of which run contrary
to the reported "real world" experience of many airlines.
Based upon information gathered in over 100 forums and visits directly
involving the airlines, and the experience of having manufactured
over 250,000 flight control ball screws in over 50 applications,
Thomson Saginaw feels it has an obligation to summarize the following:
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Relative to the Use of Silicon Carbide
Bearing Balls |
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The development of ceramic materials for design
use dates back more than 40 years. However, the use of ceramics
in the bearing industry (for bearing balls) has gained acceptance
only recently. The reasons for the restriction of ceramics in the
bearing industry were due to the fact that the cost, materials,
processing techniques, and reliability were constrictive.
The desired properties for a bearing ball are: high fracture toughness,
hardness and corrosion resistance, and low density and wear with
the failure mode being small spallation. It was not until the capability
of producing a fully dense (no porosity) silicon nitride material
was developed that any of the desired properties were produced,
and ceramic material was accepted as a production alternative
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Two ceramics were considered as potential ball
materials; silicon nitride and silicon carbide. Both the silicon
nitride and silicon carbide materials have been widely investigated.
However, only the silicon nitride has been found acceptable for
use due to the fact that in bearing tests silicon carbide fails
by fracture with an average cycle accumulation of only 1.3 x 104.
Silicon nitride, on the other hand, demonstrates an average cycle
accumulation of 6.9 x 107 and a failure mode of small spallation.
1 Clearly, both the mode of failure and abbreviated life of silicon
carbide eliminated it from consideration for use by Thomson Saginaw
in aerospace flight control ball screw assemblies.
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The overwhelming reason for ball screw overhaul
and replacement is wear. Given the large aspect ratio between ball
nut length and screw length (4:1 to 10:1, or higher), the accumulation
of wear is concentrated within the ball nut. Accordingly, any developments
in improving the longevity of trailing edge flap flight control
ball screws should be primarily focused upon reducing wear. Any
development program that attacks primarily the corrosion issues
without significantly increasing ball nut wear resistance (for instance,
via a significantly harder ball nut raceway) would most likely have
little or no impact on the "real world" life of the ball
screws.
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Submitted by David A. Lange
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Manager, Product Engineering |
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Aerospace, Government & Defense
(1) R. Nathan Katz, "Effects of Composition, Microstructure,
and Processing on Ceramic Rolling Element Bearing Performance",
Worcester Polytechnic Institute, NIST Publication "Ceramic
Bearing Technology", 1991.
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Specified for use in such high-technology industries
such as hybrid bearings, aerospace and defense; Silicon Nitride
ceramic balls feature these advanced characteristics:
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Lightweight Silicon Nitride weighs 60% less than
steel which reduces centrifugal force, skidding and wear under high
speed and acceleration.
Superior Surface Finish, Ra 0. 1 7-0.25 micro inches ' may extend
L-10 life to as much as 100 times that of steel bearings.
High Temperature Hardness is twice that of steel. These all-ceramic
balls retain their strength and hardness up to 1800 degrees F.
Silicon Nitride is further characterized by its low density of 3.2
g/cc, high flexural strength of 1.0 GPa, and fracture toughness
of 6 MPa/M2.
These outstanding properties, together with Hoover's exacting manufacturing
standards regarding sphericity, diameter tolerance, and surface
finish, make Hoover's silicon nitride balls ideal for high performance
ball bearings.
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Material Analysis: |
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Property/Material
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Aluminum Oxide
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Zirconium Oxide
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Silicon Nitride
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Chemistry (wt%)
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99.5% Al2O3.5% Other
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97% ZrO2 3% MgO
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87% Si3N4 13% Other
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Hardness
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1700 Hv
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80-84 Ra
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1400-1700 Hv
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Density (gm/cc)
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3.87
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5.6
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3.22/3.25
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Transverse Rupture
Strength (psi)
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45,000
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90,000
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145,000
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Ultimate Compressive
Strength (psi)
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300,000+
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285,000
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570,000+
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Ultimate Tensil
Strength (psi)
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31,000
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60,000
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Modulus of
Elasticity (psi)
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53 x 10^6
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29 x 10^6
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44-45 x 10^6
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Maximum Work
Temperature
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1400 Celsius
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815 Celsius
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1000 Celsius
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Fracture Toughness
(K1c)MPa/m
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4
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10
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6-8
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Available Grades & Silicon Nitride
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Grade |
Size Range (inches) |
3 |
.5mm - 2" |
5 |
.5mm - 2" |
25 |
.5mm - 2" |
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Technical Reference- Questions about
Hybrid Bearings |
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What Is A Hybrid Bearing? |
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A hybrid bearing is made up of metal rings and
silicon nitride ceramic balls with lubricant and retainer appropriate
to the type of bearing and application. The silicon nitride balls
typically allow for higher speeds, lower operating temperatures,
extended lubricant life, and many other performance enhancements.
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Why Do CERAMIC Silicon Nitride Balls
Improve Bearing Performance? |
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Compared to steel balls, CERAMIC balls are lighter,
smoother, stiffer, harder, corrosion resistant, and electrically
resistant. These fundamental characteristics allow for a wide range
of performance enhancements in bearings.
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Are Ceramic Balls Brittle and Fragile? |
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No. Silicon Nitride ceramic balls do not have as
high a toughness or ductility as steel. But, due to their high strength,
stiffness, and micro structural make-up, they are actually much
more durable than steel balls.
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Compare The Material Properties of
Silicon Nitride Balls to Steel Balls. |
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CERAMIC balls are >60% lighter, >50% stiffer,
>70% smoother, and much, much harder than steel balls. CERAMIC
balls have >100X better rolling contact fatigue life in comparison
to Vacuum Melt 52100 Steel
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What Applications Use Hybrid Bearings? |
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The most common application today is angular contact
bearings for high speed machine tool spindles. End-users are seeking
higher speed, longer life, reduced lubrication, and decreased total
operating costs. CERAMIC balls are used in a very wide range of
applications from dental handpieces to surgical saws to wing-flap
actuators to electric motors
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Are CERAMIC Balls More Expensive
Than Steel Balls? |
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Yes. In direct comparison, CERAMIC balls are clearly
more expensive than steel balls. BUT, when assembled into a hybrid
bearing, the price of the bearing assembly is actually quite competitive
when compared to all steel bearings. On a Total Operating Cost basis,
hybrid bearings typically always pay for themselves many times over
in extended life time, enhanced performance, or increased durability.
Over the past 15 years, CERAMIC balls have steadily become more
and more affordable for a wider range of applications as the volumes
have climbed
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How Do You Make a CERAMIC Ball? |
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CERAMIC balls are made from an ISO-9000 certified
process starting with micron sizes powder which is compacted and
then densified at extremely high pressures and temperatures. The
densified blanks are then precision finished using free-abrasive
diamond lapping procedures. Grade 3 and 5 precision levels are typical
in high volume batch sizes.
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How Are Precision Balls Specified? |
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CERAMIC balls (and any other finished ball from
all materials) are specified by using ABMA, ISO, JIS, ASTM or other
standards. The sphericity, surface finish, lot diameter variation,
etc. are precisely defined by these standards into various ¡°Grade¡±
levels. The highest typical Grade is 3 (denoting 3 millionths sphericity
or better), then 5, then 10, etc¡.. Bearing companies use
different grades depending on the bearing precision and application.
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How Much Longer Life Can Be Expected
From Hybrid Bearings Vs. Steel? |
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This is a tough question. Generally speaking, one
can expect 2 to 5 times longer life for most applications, but it
is highly dependent on operating conditions, bearing design, etc.
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What CERAMIC Ball Sizes Are Available? |
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This is an easy question. CERAMIC balls are readily
available from 0.5 mm (about 1/64¡±) to 25mm (1¡±)
in a variety of ball grades. CERAMIC balls can be made up to 3¡±
(75mm) in diameter. The most popular sized balls tend to be from
1mm to 13 mm in terms of quantity used.
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How Can I Buy CERAMIC Balls? |
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Simple. Just contact "Jayashree
Business & Consulting Engineers" Pune |
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Q: Is there any advantage to using
high heat, high speed bearings? |
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A: Most standard bearings are rated to run
at speeds far greater (up to three times greater) than your engine
will turn. It is unlikely that you will notice any benefit by paying
more money for bearings rated faster than this. It is like buying
racing tires for your family car. Sure the tires can safely run
200mph, but your car can¡¯t!
On the other hand, special bearings such as Hybrid
Ceramic (Bearing steel races with Silicon Nitride balls) and Stainless
Ceramic (Stainless Steel races and Silicon Nitride balls) offer
distinct advantages in certain applications. The price of Ceramic
bearing has been coming down in recent years, making them a viable
alternative to ultra-expensive exotic specialty bearings
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Q: What are the advantages of Ceramic
bearings? |
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A: Silicon Nitride (Si3N4) balls
have several advantages over steel balls: |
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They are up to 2 times harder so they last
a lot longer.
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They less than 1/2 the weight of steel so
they can accelerate faster and place less loads on the rest
of the bearing at very high speeds.
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They can be made to much tighter tolerances
and surface finishes so they need less lubrication and run
quieter.
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They can withstand much higher temperatures
(800 deg C) and expand 1/4th as much as steel balls, so they
retain proper clearances even when the engine is running very
hot
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They are virtually inert, meaning that chemicals
do not harm them and they will not rust
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They are non-magnetic so they do not attract
other ferrous metal particles which can damage the races.
High Speed ¨C Oil mist lubricates up to three million
DN with reduced skidding, wear, and heat generation; grease-lubricated
hybrids up to one million DN. Ion doped races with self lubricating
retainers require no hydrocarbon or fluorocarbon lubrication.
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Good oxidation resistance |
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Extended Operating Life ¨C 3 to 5 times
greater than that of steel when properly applied.
Marginal Lubrication ¨C Ion doped races with self-lubricating
retainers require no hydrocarbon or fluorocarbon lubrication. By
using dissimilar materials (ceramic on steel) microscopic adhesion
welding is eliminated.
Corrosion Resistance ¨C Ceramic material resists corrosion
and galling while thin-dense coating may be used to enhance hybrid.
High Stiffness ¨C Modulus of elasticity 50% greater than
steel increases bearing rigidity.
Low Torque ¨C Low friction, even without conventional
lubrication, with extremely fine surface finishes.
Long Wear Life ¨C High hardness of Rc78 greatly extends
bearing wear characteristics.
Light Weight ¨C 60 % lighter than steel, reducing centrifugal
forces and overall system weight.
Special Properties ¨C All ceramic components are: - Non
magnetic- Electrically non conductive.
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Q: What is the difference between
Hybrid Ceramic bearings and Stainless Ceramic bearings? |
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A: Hybrid Ceramic bearings use ceramic balls
and regular bearing steel races. These bearings offer the best longevity
at a reasonable cost. Stainless Ceramic bearings use ceramic balls
with stainless steel races. Although stainless steel used for bearings
is slightly less hard, when used with ceramic balls, offers nearly
equal longevity with the added benefit of not rusting.
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Q: Which one should I use? |
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A: If you only use your engines occasionally
and are careful to keep them well lubricated and dry, standard bearings
are probably the most economical for you. If you use your engines
hard, in dusty or hot conditions or with high nitro fuels, Hybrid
Ceramics may be a better choice. If you demand the highest performance
from your engines and rust is a problem, Stainless Ceramic bearings
offer the ultimate in performance and protection.
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Q: What are standard bearings made
of? |
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A: A common material is a Chrome steel alloy,
also known as GCR15 (AISI 52100). Metal shields are made from stainless
steel, one alloy being SPCC JISG314. Our standard bearings are made
from these industry standard materials.
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Q: I have heard about special plastic
retainers used in some bearings. Are they really worth the extra cost?
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A: In most cases, the steel or brass retainers
in standard bearings will work just fine and you will not likely
notice any difference in operation. In special, high speed or racing
applications, a special retainer may help. Many Ceramic bearings
use a removable retainer so that the races can be replaced when
they wear out, saving the expensive balls.
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Q: What are hybrid bearings? |
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A: Hybrid bearings are equipped with rings
made of steel (chrome steel or stainless steel), with balls made
of ceramic materials (silicon nitrite or aluminium oxide) and cages
made of different materials depending on the application they are
needed for.
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Range of application: |
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Lack of lubrication |
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High rate of revolutions |
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Corrosive environment |
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Humidity, acids, leaching solutions,
aggressive detergents... |
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High temperatures |
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Electric isolation |
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Use in: |
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Vacuum technology |
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Electrical equipment & welding |
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Micro technology |
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