Balls / Silicon Nitride
  Silicon Nitride (Si3N4) Balls are used by World Leaders in the field of  
  Machine Tools : Spindle bearings, Ball Screws.  
  Spindles mfg. by GMN Spindles USA run at 42000 rpm, (11 kW) with power ranging upto 80kW by using Si3N4 balls.  
  Fuel Systems : Relief Valve applications : Siemens VDO Automotive  
  Electric Motors  

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

  Injection Molding machines: Electromechanically operated by Ball screw and Electric Drive motors.  

Spindles in Textile Industry where atmosphere is moist always, Majority of Textile Industries in Europe & USA use Silicon Nitride Balls for Spindles


"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.

  "We've had great results from your silicon nitride probes." - S. Schanhals  
  Eaton/Saginaw, Saginaw MI  
  The leaders use it because Silicon Nitride Balls have following properties.  
It overcome heat, reduce vibration levels and Wear problems
Smooth and over 1 G acceleration capacity
Can be operated at 30% higher speed than that of steel balls
Enhances life by 100% or more
Improved Rigidity and Accuracy
Ultra Smooth surface and Chemical inertness
Lower thermal expansion 2.9 x 10 (-6).
Maximum use temperature 1000 deg C
Very High compressive Strength 3000 CPA
High Hardness > 78 HRC
Lowest Density 3.2 g/cc
High Young's Modules 320 Gpa
Excellent Corrosion Resistance
Completely Non-Magnetic and Insulator
Ball Fatique life > 100X
  What the experts say.  

" 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.


" 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.

  Mr. Jeff Wickwire, Quality Assurance Representative, DCM Buffalo, New York.  

" 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.


"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

  Typical Applications of Silicon Nitride Balls  
High Speed
        - Machine Tool Spindles
  - Turbochargers
  - Hard Disk Drive Spindles
  - Dental Handpieces
  - Textile Spindles
  - Ball Screws
  - Air Driven Power Tools
Extremely Low Lube
        - Surgical Handpieces
  - Semiconductor Processing Eqpt.
  - Turbo Molecular Pumps
  - Liquid Molecular Pumps
  - Flow & Gas Meters
Clean Environment (Low Particulate Emissions)
        - Semi-Conductor Processing Equipment
  - Computer Hard Disk
  - Production Machinery
  - LCD Panel Production Machinery
Corrosion Resistance
        - Film Manufacturing Machinery
  - Food Processing Eqpt
  - Chemical Processing Eqpt
  - Sucker Rod Pump Check Balls.
Low Torque
        - In-Line Skates
  - Aerospace Instruments
  - Robotics
Extreme Temperature
        - Liquid Oxygen Pumps
  - Kin Cars
  - Ovens & Metal Processing Eqpt.
        - Turbo Molecular Pumps
  - Semiconductor Processing Eqpt.
Oscillating Motion
        - Scanner
  - Robitics
  - Hard Disk Drive Actuators
Contamination & Wear Resistance
        - Electric Motors
  - Paper Processing Eqpt.
  - Air Driven Power Tools.
Electrical Resistance/Nonmagnetic
        - Electric Motors
  - Paper Processing Eqpt.
System Rigidity and Accuracy
        - Kinematic Mounts
  - Machine Tool Ball Screws
  - HDD Spindles

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


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.

More "down-to-earth" applications include bearings for:
      Machine tool spindles
  Computer hard disk drives
  Turbomolecular vacuum pumps
  High performance bicycles and inline skates
  Aircraft APU's and starter motor/generators
  Food processing equipment

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.

  Key Properties  
  Applications exploit the following properties of silicon nitride:  
      low density
  high temperature strength
  superior thermal shock resistance
  excellent wear resistance
  good fracture toughness
  mechanical fatigue and creep resistance
  good oxidation resistance

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.

  Industrial Applications  
  Pertaining to Trailing Edge Flap Ball Screw Assemblies For Use on Boeing Model 737-100, -200, -300, -400, and -500 Airplanes  

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

  Reference: Boeing Service Letter 737-SL-27-108 (ATA:2754-40) dated 21 May 1996  

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:

  Relative to the Use of Silicon Carbide Bearing Balls  

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


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.


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.

  Submitted by David A. Lange
  Manager, Product Engineering  

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.


Specified for use in such high-technology industries such as hybrid bearings, aerospace and defense; Silicon Nitride ceramic balls feature these advanced characteristics:


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.

  Material Analysis:  
Aluminum Oxide
Zirconium Oxide
Silicon Nitride
Chemistry (wt%)
99.5% Al2O3.5% Other
97% ZrO2 3% MgO
87% Si3N4 13% Other
1700 Hv
80-84 Ra
1400-1700 Hv
Density (gm/cc)
Transverse Rupture
Strength (psi)
Ultimate Compressive
Strength (psi)
Ultimate Tensil
Strength (psi)
Modulus of
Elasticity (psi)
53 x 10^6
29 x 10^6
44-45 x 10^6
Maximum Work
1400 Celsius
815 Celsius
1000 Celsius
Fracture Toughness
  Available Grades & Silicon Nitride  
Grade Size Range (inches)
3 .5mm - 2"
5 .5mm - 2"
25 .5mm - 2"
  Technical Reference- Questions about Hybrid Bearings  
  What Is A Hybrid Bearing?  

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.

  Why Do CERAMIC Silicon Nitride Balls Improve Bearing Performance?  

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.

  Are Ceramic Balls Brittle and Fragile?  

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.

  Compare The Material Properties of Silicon Nitride Balls to Steel Balls.  

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

  What Applications Use Hybrid Bearings?  

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

  Are CERAMIC Balls More Expensive Than Steel Balls?  

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

  How Do You Make a CERAMIC Ball?  

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.

  How Are Precision Balls Specified?  

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.

  How Much Longer Life Can Be Expected From Hybrid Bearings Vs. Steel?  

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.

  What CERAMIC Ball Sizes Are Available?  

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.

  How Can I Buy CERAMIC Balls?  
  Simple. Just contact "Jayashree Business & Consulting Engineers" Pune  
  Q: Is there any advantage to using high heat, high speed bearings?  

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

  Q: What are the advantages of Ceramic bearings?  
  A: Silicon Nitride (Si3N4) balls have several advantages over steel balls:  

They are up to 2 times harder so they last a lot longer.


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.


They can be made to much tighter tolerances and surface finishes so they need less lubrication and run quieter.


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


They are virtually inert, meaning that chemicals do not harm them and they will not rust


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.

Good oxidation resistance

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.

  Q: What is the difference between Hybrid Ceramic bearings and Stainless Ceramic bearings?  

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.

  Q: Which one should I use?  

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.

  Q: What are standard bearings made of?  

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.

  Q: I have heard about special plastic retainers used in some bearings. Are they really worth the extra cost?  

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.

  Q: What are hybrid bearings?  

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.

  Range of application:  
     - Lack of lubrication
  - High rate of revolutions
  - Corrosive environment
  - Humidity, acids, leaching solutions, aggressive detergents...
  - High temperatures
  - Electric isolation
  Use in:  
     - Vacuum technology
  - Electrical equipment & welding
  - Micro technology