Preload & Duplex Ball Bearings by PKB

Axially preloading of bearings provides the following benefits:

  • Increases ring rigidity
  • Applies pressure to the ball and raceways, eliminating slip or skidding
  • Lowers the possibility of non-repeating runout
  • Reduces contact angle variation between the inner and outer raceways


  • Spring Preloading – Using various types of springs
  • Washer / Spacer Preloading – adding a precision ground washer/spacer between the inner or outer rings, removing axial and radial play
  • Duplexing, which entails the precision grinding of the actual bearing faces.

SPRING method is the simplest method.  This method is less sensitive to thermal expansions and contractions.  It can also accommodate some misalignment in the system.

WASHER/SPACER method is a more tedious process requiring precise measurements of the endplay and matching it with precision washer/spacers.  This method is not as forgiving when subjected to thermal expansions and contractions or misalignment.

DUPLEX method is a process of removing material from a pair of bearing faces to adjust raceway offsets.  Clamping the bearing faces together creates the internal preload.  Duplex sets assist in satisfying the requirements of increased radial and axial stiffness, and also provide deflection control.


There are (3) methodologies:


The following illustrates PKB’s standard marking scheme for each of the Duplex methodologies. 

The “V” in the Tandem set point in the direction of the axial force applied to outer ring.

If you have any questions or inquiries regarding duplex sets, contact us anytime.

Read More

Bearing Handling Practices  

Bearing Handling Practices  


Bearing handling is as important as bearing design and cleanliness.

Improper handling can contaminate or damage the bearing assembly.

Proper handling and installation helps to maximize bearing performance and bearing life.


Some Tips:

  • Bearings should be kept in their original and unopened PKB packaging until ready to use.
  • Open each bearing, one at a time, as needed for installation purposes.  Do not open extra bearings or expose unused bearings to the environment.
  • Unused bearings should be kept in their original, protective PKB packaging.
  • Bearings should be handled in a dust free environment that is clean, dry and free of static.
  • Clean, lint-free garments should be worn by anyone that enters the work area.
  • Fluids, solvents, and other materials that are not part of the assembly process should be kept away from the assembly area to prevent contaminating the bearings.
  • Machining, filing, soldering, grinding, etc should be kept away from the assembly area to prevent contaminating the bearings.
  • All tooling and instruments should be non-magnetic.  It is important to keep tooling and instruments clean and properly maintained to avoid burrs or other potential contaminants.
  • Bearings should be handled with specially designed hand held instruments, such as plastic tweezers or tweezers with special work tips.
  • In situations where the bearings must be handled by hand, it is important that clean, dry, unused, and lint free gloves and finger cots should be utilized.  Never touch the bearings with bare hands or fingers.
  • Tooling and instruments should be cleaned with a spray, not sloshed in a bath of solvent.  Sloshing may allow cross contamination.
  • Bearings, tooling & instruments must be kept demagnetized.  Should magnetism become evident, utilize a demagnetizer before exposing the bearing to the work environment.
  • Any unused bearings that were removed from the PKB protective packaging should be stored in clean, dry containers, with proper identification labels.  A clean anti static glass covered dish is often an acceptable storage container between work shifts.
  • See our Bearing Installation page for more information about proper installation of the PKB bearing into your device. 


Contact us with any miniature ball bearing requirements you may have.

Read More

Clean-Room Services

PKB’s Clean-Room Bearing Maintenance and Re-lubrication Center meets Class-6, with Class-5 Clean Benches, per ISO 14644-1. 

PKB manufactures bearings up to 1.125" O.D.

PKB manufactures bearings up to 1.125″ O.D.

Pacamor Kubar Bearings is pleased to offer clean-room services.

Have your ball bearings been in a stock room for 3 years or longer?  

Is the lube discolored or the packaging damaged?

Did your stockroom temperature and humidity ever fluctuate?  

PKB’s quality certified factory and clean-room are the right place to refurbish your ball bearing inventory.



Who better, than the ball bearing manufacturer, to re-lubricate your aging bearing inventory?   

Clean-Room Services:

  • Wash & re-lube with the same lubricant
  • Wash & change the lubricant to a different lubricant and/or lubrication process 
  • Options include, but not limited to:
Lube Weight Documentation

Lube Weight Documentation

    • Grease 
    • Oil
    • Grease Plate
    • Oil Film
    • Oil Plate
    • Serialization
    • Dip & Drain
    • Dry-Film Lubricants (Dicronite, etc.)
    • Lube Dry (wash only)
    • Vacuum Impregnation
    • Lubricant & Solvent Mixtures
    • Lube Weight Documentation
    • PKB Stock Lubricants
    • PKB Specialty Lubricants
    • Customer-Supplied Specialty Lubricants
  • Bearings repackaged in PKB Standard Clean Bags
  • Bearings repackaged in specialty bags, to your specification
    • Intimate bearing packaging in Class 6 Clean Room, with Class 5 Clean Benches, meeting ISO 14644-1.
  • Packaging options include, but not limited to:
    • Nitrogen purge
    • 1A8 bags
    • Vial pack
    • Pill pack 
    • MIL-197
    • Kitting
    • Other specialty packaging materials & processes


 Why Maintain Proper Bearing Lubrication?

Class 6 Clean Room with Class 5 Clean Benches, meeting ISO 14644-1

Class 6 Clean Room with Class 5 Clean Benches, meeting ISO 14644-1

Proper lubricant can reduce friction, prevent bearing wear, protect bearing surfaces from corrosion, and carry away excess heat during bearing operation.  

Bearings operate on a very thin film of lubricant which must be maintained, or replaced, to ensure that maximum bearing life is achieved.  

Proper selection, application, and maintenance are vital in maximizing bearing life.  

Maintaining your bearings with proper lubrication will reduce friction and wear.   


Can PKB Re-lube Bearings That Were Manufactured By Other Companies?

Yes. PKB regularly performs re-lubrication services on bearings that were originally manufactured by other bearing companies.    


When Should Bearings be Re-lubed?

PKB recommends that bearings should be re-lubed within three (3) years of the original manufacturer’s lube date, or if any of the following conditions occur:

pacamor cleanroom

  • Bearings have been subjected to temperature or humidity conditions outside of the recommended temperature range
  • Bearings have become contaminated 
  • The original packaging has become damaged
  • If you’re unsure of the lubricant’s expiration date
  • There is any question about the quality, condition, or type of lubricant in the bearings
  • The bearing lubrication appears to have separated, discolored, or otherwise changed appearance 


Can’t I Just Wash Out the Lubrication and Install New Lube?

Many 440C Stainless Steel Bearings that are used in Aerospace, Medical, and other applications, can be cleaned and re-lubricated, in proper clean-room conditions, and by trained personnel. Improper handling can result in cross contamination, problems with wettability on balls & bearing races, or ball & raceway damage. Other components affected or broken, are the retainers, seals, shields, balls, or wires.  PKB provides bearing wash and re-lubrication services, for many Aerospace OEM’s and authorized re-sellers, in our factory clean-room.




Bearing Lubrication – Most Requested Oils
Lubricant Type Viscosity (Centistokes)
 @ 100 F
Viscosity (Centistokes)
 @ 210 F
Operating Range (F) Mil-Spec



DIESTER 31 5.3 -65 to +300 MIL-L-6085A
ANDEROL 401D DIESTER 11.5 3.2 -65 TO +300
DC 510 SILICONE 38 14 -65 to +500 MIL-L-27694


Bearing Lubrication – Most Requested Greases
Lubricant Base Oil Thickener Color Operating Range (F) Mil-Spec


 Please Contact PKB for a quote to rework your in-house bearings, with new lubricant, or to make a lubricant change. 

pkb cleanroom

More about Bearing Lubrication from PKB:


The most popular bearing lubricants are listed on our Lubrication Page. Many more oil, grease and dry-film lubricant options are available, upon request. 

More How-To Guides:

Read More

Domestic Ball Bearings For Small Motor Applications

We are excited to discuss with you our miniature and instrument bearing capabilities. 

PKB manufactures ball bearings for some of the world’s most respected small motor brands. 

We also offer:



Shorten your ball bearing lead times with our domestically produced bearings, manufactured and assembled in Troy, NY. 


Best prices in the domestic bearing industry!

Reduce your domestic ball bearings costs with our Veteran-American Owned & Operated Small Business. 


Expedite time to market for your new and updated products. 


Your engineers will love our speedy delivery of engineering prototypes and evaluation samples.

Here is a testimony, about PKB bearings, for small motor applications, from Kearfott Guidance & Navigation

Here is a testimony from another happy customer. This one is for PKB cryogenic bearings for Flowmeter applications, from the President of Hoffer Flow Controls

Our wide range of miniature and instrument bearings are used in an array of small motors, actuators, encoders, often found in aerospace, space, military, medical and surgical applications. 

We have proudly supplied products for the NASA Docking Station, NASA James Webb Space Telescope, MARS 2020 Rover, Sikorsky Helicopters, Cryogenic Flowmeter Applications, FAA TSO-C149 Aircraft Bearing applications, many military and Department of Defense (DoD) applications, as well as other space, aerospace, medical, and customized applications.  


Pacamor Kubar Bearings –

Read More

That Hard-to-Find (or Easy to Find) Ball Bearing Might be Counterfeit

The bearing industry was once again rocked by news of widespread counterfeiting. Bearing manufacturer SKF reported the identification and destruction of 15 tons of counterfeit bearings, totaling approximately 17,000 bearings. 

Automotive World     

As quoted in the Automotive World articleEnd customers that install counterfeit components will suffer the most. A recent case proved once again that significant damage can be caused by the failure of a rolling bearing. An anonymous customer says: “We spent EUR 100,000 on large size bearings, purchased from an un-authorized supplier. We needed the bearings urgently and the supplier matched our required lead time. Their failure was a fact after only a few months, while the expected service life was several years. We faced costly downtime and broken promises to our customers. All this could have been avoided, by more awareness and caution in our sourcing. We will not allow this to happen again.”

Ed Osta, President of Pacamor Kubar Bearings (PKB), warns against the ease of getting duped by counterfeit bearings. “Tight profit margins combined with the influx of cheap import products make bearings an extremely competitive business”, says Osta. “Counterfeit bearings may resemble the branded product, at first glance. However, they may have been manufactured using substandard materials, not to standard ABEC tolerances and assembled in less than optimal conditions. These discrepant bearings can often fail, sometimes destroying an entire system along with the reputation of the system’s manufacturer. When parts are destined for critical applications, even the smallest nonconformity can cause catastrophic failures.”

Pacamor Kubar Bearings (PKB) is deeply concerned by these risks to parties who put their trust in counterfeit and unapproved parts. PKB takes pride in product quality, workmanship, knowledge and skill as experts in the production of high quality aerospace bearings. The entire PKB factory is AS9100 Rev D & ISO 9001:2015 certified and all of the DFARS approved products are FAA TSO-C149 Aircraft Bearings certified. If the package isn’t shipped directly from PKB, or from one of a very few PKB approved re-sellers, be sure that the product you are buying is original PKB manufactured product.

Contact PKB directly or through a very short list of approved distributors.

Authentic PKB Aerospace Bearing at the Pacamor Kubar Bearings factory in Troy, NY.

Authentic PKB Aerospace Bearing at the Pacamor Kubar Bearings factory, in Troy, NY.

Why work with us? 

American Owned & Operated


Shorten your ball bearing lead times with our domestically produced bearings, manufactured and assembled in Troy, NY. 


Best prices in the domestic bearing industry!

Reduce your domestic ball bearings costs with our Veteran-American Owned & Operated Small Business. 


Expedite time-to-market for your new and updated products. 


Your engineers will love our swift delivery of bearing prototypes and evaluation samples. 


S/N Precision Enterprises Inc., dba Pacamor Kubar Bearings – Cage Code 14927

Read More

Pacamor Kubar Bearings(PKB) Awarded Contract to Support Mars 2020 Mission

Pacamor Kubar Bearings (PKB), a Troy, NY manufacturer of ball bearings for aerospace and defense systems, was recently awarded a contract by Sierra Nevada Corporation (SNC) to supply critical hardware for the Mars 2020 mission. Scheduled to launch in 2020, the robotic science rover will investigate key questions about the habitability of Mars and assess natural resources and hazards in preparation for future human expeditions to the red planet. Under the new contract, PKB will manufacture ball bearings for several motors in the robotic arm actuator and sample caching system. The instruments will enable scientists to identify and select a collection of rock and soil samples that will be analyzed and stored for potential return to Earth.

“PKB has been supporting NASA’s Jet Propulsion Laboratory (JPL) programs and missions for over 10 years,” said Ed Osta, president of Pacamor Kubar Bearings. “We are grateful for NASA and SNC’s continued confidence in our ability to produce reliable aerospace bearings for these vital missions. PKB is committed to the success of this mission and proud to partake in this project. We look forward to continuing our longstanding relationships with JPL and SNC.”

PKB understands the unique challenges presented by aerospace and guidance applications. Temperature extremes and the vacuum of space create demanding requirements for the lubricant type and its ability to withstand the environment. To meet this demand, PKB is providing precise and reliable products in support of successful missions.

“SNC appreciates the PKB’s commitment to deliver the promised product within the assured timeline,” said Jason Priebe, vice president of productions/operations for SNC’s Space Systems business area. “Reliable suppliers are crucial to developing a final product that you’re proud to stand behind.”



PKB is ISO9001:2015 and AS9100D certified, which includes the additional QS requirements specific to the aerospace industry. The company attained certification from the FAA to manufacture bearings per the requirements of TSO-C149, thereby enabling it to provide bearings as replacement parts to FAA certified repair stations. PKB is JCP-Certified, which is a joint certification program with United States and Canada. 

Pacamor Kubar Bearings manufactures high performance DFARS-compliant miniature and instrument ball bearings for the aerospace, defense, medical, industrial and commercial industries. Customers include major aerospace manufacturers and key re-sellers as well as various national laboratories and prestigious government organizations such as NASA. PKB provides these industries with precision ball bearings, including those with unique designs and materials used at sub-cryogenic temperatures.

For more information on PKB, please follow us on our facebook page, and on our instagram feed.

Pacamor Kubar Bearings offers the right bearing at the right price, for all your miniature, precision, and instrument applications.

Read More

Getting The Most Out Of High-Speed Bearings

Service Spotlight: 
Miniature & Micro Ball Bearing Efficiency
Bearing speed is affected by a variety of factors including bearing geometry. Bearing rings must be ground to very tight tolerances and polished to a smooth and shiny finish. Bearing steel must be of high quality with small, evenly spaced carbides. Large carbides and inclusions reduce the quality of the steel and create “tear outs” and “comet tails” in the raceway. This not only slows the bearing, but shortens the life of the bearing. Similarly superior ball quality must be maintained for optimal performance. Pacamor Kubar Bearings (PKB) uses only the most reputable steel and ball vendors to ensure reliable, repeatable quality in all our domestically produced miniature ball bearings. The bearing retainer/cage must be produced from high quality materials and piloted in such a way, that it does not drag on any of the bearing components. Retainer drag will not only slow the bearing rotation, but will result in premature failure of the bearing assembly. Proper lubrication will enhance bearing performance and extend bearing life. Too much or too little lube or the wrong viscosity of bearing lubricant will also impair bearing performance.
Some limiting factors include component quality, lubrication density, retainer material and design. The upper level assembly into which the bearing will be placed can also limit the bearing speed. Atmospheric conditions such as contamination, ambient or fluctuating temperatures, and moisture all impact the bearings speed capabilities. It is important to discuss the bearing’s operating environment with PKB, to be sure that vacuum conditions, salt baths, and other environmental factors are considered for optimum performance.
Special coatings, various ball and retainer materials and a wide range of bearing lubricants are available to satisfy specific environmental conditions, speed, temperature, and other factors.
Bearings are an essential component in many products and assemblies. The bearing allows the shaft to turn and control speed and vibration in an assembly. Getting product to market expeditiously is crucial to any project plan. A bearing designed from standard envelope dimensions with minimal special features will help contain project costs and reduce component lead times. When choosing a bearing, refer to the standard bearing envelope dimensions offered, and work with PKB to satisfy the specific requirement.
PKB manufactures bearings for all miniature and instrument applications. PKB miniature bearings are found in medical and surgical handpieces, bone saws and drills, and fluid pumps for the medical industry. PKB produces annular bearings for miniature motors, actuators, and electrical sub assemblies for robotic applications such as pick-and-place robots and packaging equipment. PKB instrument bearings are used in guidance and missile applications as well as specialty products produced for rocket booster components.
Customer Testimonial:Hoffer Shuttle

“We used to advise after 3 months to a year that we recommend changing the bearings; several years ago we stopped changing the bearing…We have not changed a bearing for years and have had no failures due to bearing wear…the bearings are exactly the same which is amazing!!”

Read the Full Testimonial

PKB = Quality + On-time + Competitive + USA Made
  • Made in Troy, NY USA 
  • AMERICAN owned and operated Small Business
  • VETERAN owned and operated
  • DFARS-compliant
  • ISO 9001:2015 certified
  • AS9100D certified factory 
  • FAA TSO-C149 Aircraft Bearings
  • ISO 14644-1 Class 6 Clean Room
  • ISO 14644-1 Class 5 Clean Benches
  • U.S. / Canada JCP Certified
  • In-house DMIR for expedited aerospace projects 
  • Lowest prices of ANY domestic ball bearing manufacturer. Let us show you!
Let our engineers help you, with recommendations, or assistance with your bearing design! 
What bearing attributes are closely linked to speed, and how?
Handheld Micrometer
Speed is affected by many factors, including bearing geometry. Bearing rings must be ground to tight tolerances and polished to a smooth and shiny finish. Bearing steel must be of high quality with small, evenly spaced carbides. Large carbides and inclusions reduce the quality of the steel and create “tear outs” and “comet tails” in the raceway; this slows the bearing and shortens its operating life. Finally, retainers must be piloted so they do not drag on any of the bearing components. Retainer drag slows the bearing and results in premature assembly failure.

Link to Additional Resource

What are some of the limiting factors associated with speed, and how do you overcome them?
The upper-level assembly into which bearings are placed can limit speed. Contamination, ambient or fluctuating temperatures, and moisture as well as vacuum conditions, salt baths, and other environmental factors should be considered for optimum performance. Special coatings, various ball and retainer materials, and a variety of bearing lubricants satisfy specific environmental conditions, speed, temperature, and other factors.

Link to Additional Resource


Read More

How-To Guide: Estimating Life of Miniature Ball Bearings

How-To Guide: Estimating Ball Bearing Life 
Pacamor Kubar Bearings(PKB), is continuing our HOW-TO GUIDE series with some suggestions for estimating ball bearing life.  We hope this will help you to maximize bearing life and performance.
How-To Guide: Estimating Life of Miniature and Instrument Ball Bearings

“Life” is the number of hours that a percentage of similar bearings have survived under an essentially identical set of operating conditions and loads.  Life can be affected by a number of factors including loads, speed, lubrication, fit, maintenance, temperature, contamination, and others.

Bearing life is defined as the length of time (number of revolutions) until a specific failure occurs. Predicting the life of a ball bearing is a statistical calculation of the fatigue properties of the various bearing components. Fatigue Life (L10 or Rating Life) of bearings is the number of hours or revolutions reached by 90% of a group of bearings subjected to the same loads before the onset of fatigue.  Conversely, 10% of the same group of bearings can be expected to show evidence of fatigue before the L10 Life is reached. 

Many variables can impact bearing life.  Various factors such as handling and contamination damage can dramatically reduce bearing life.  Bearings should be properly stored, mounted, dismounted, and inspected.  Optimized performance and life is also contingent on appropriate lubrication and sufficient protection from foreign matter.  Bearings should be stored in a cool, clean, low humidity environment free of dust, shocks and vibrations.  Proper fitting, using specialized tools and techniques, will also help maximize bearing life. 

tapered ODFor further assistance with bearing selection and design, please feel free to contact our engineering team.  Catalog bearings, of all sizes produced by PKB, can be configured as Angular Contact, Radial, or Full-Complement types.  PKB also manufactures a wide range of Thin-Section and Metric bearings.


See our Bearing Installation Guide & Bearing Handling Practices pages for more information about proper installation of a PKB bearing into your device. Be sure to visit our Shaft and Housing Fits page for a detailed chart and more information about this topic.


For further assistance with bearing selection and design, please e-mail

Pacamor Kubar Bearings manufactures DFARS-approved FAA TSO-C149 Aircraft Bearings in its ISO 9001:2015 certified factory, in Troy, NY.


Read More

PKB Is U.S. / Canada Joint Certification Program (JCP) Certified

United States/Canada Joint Certification Program 

Pacamor Kubar Bearings (PKB) is JCP Certified. A Joint Certification Program is required by U.S. or Canadian Government Contractors wanting to obtain access to unclassified technical data drawings disclosing military critical technology with military or space application that is under control of, or in the possession of, the U.S. Department of Defense (DOD) or the Canadian Department of Defense. 

Some historical JCP background

The United States (U.S.) and Canada:

  • Share a unique, long-standing military and economic relationship. 
  • Are partners in the joint defense of North America and have established a bilateral common structure (NORAD) for mutual defense 
  • Consult and cooperate on the development of common industrial security procedures and technology controls
  • Have entered into numerous bilateral agreements that codify and support this relationship
  • In 1985, signed a Memorandum of Understanding (MOU) that established the U.S.-Canada Joint Certification Program (JCP)

The JCP:

  • Was established to certify contractors of each country for access, on an equally favorable basis, to unclassified technical data disclosing critical technology controlled in the U.S. by Department of Defense (DOD) Directive 5230.25 and, in Canada, by the Technical Data Control Regulations
  • Is managed by the U.S./Canada Joint Certification Office (JCO)

The JCO:

  • Is a common, jointly staffed office
  • Receives and processes the DD Form 2345

Our Certificate

Read More