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
COMMON TECHNIQUES
- 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:
PRELOADED PAIR MARKING
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. sales@pacamor.com
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.
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.
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
-
- 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
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:
- 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 |
|
WINSOR L245X |
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 |
| KRYTOX143AC | FLUOROCARBON | 260 | 26 | -30 TO +550 | – |
| Bearing Lubrication – Most Requested Greases | |||||
| Lubricant | Base Oil | Thickener | Color | Operating Range (F) | Mil-Spec |
| ROYCO 27 | DIESTER | LITHIUM | BROWNISH | -100 TO +300 | MIL-G-23827 |
| BEACON 325 | DIESTER | LITHIUM | LIGHT TAN | -65 TO +250 | MIL-G-3278 |
| BRAYCOTE 601 | PERFLUORINATED POLYETHER | TETRAFLUORO-ETHYLENETELOPMER | BEIGE | -100 TO +500 | – |
| MOBIL 28 | HYDROCARBON | CLAY | DARK RED | -65 TO +350 | MIL-G-81322 |
| SRI-2 | MINERAL | POLYUREA | BLUE / GREEN | -20 to +350 | MIL-G-3545G |
| KRYTOX 240AC | FLOURINATED GREASE | VIDAX | WHITE | -30 TO +550 | MIL-G-27617 |
| AEROSHELL 22 | SYNTHETIC HYDROCARBON | MICROGEL | AMBER | -85 TO +400 | MIL-G-81322 |
Please Contact PKB for a quote to rework your in-house bearings, with new lubricant, or to make a lubricant change.
sales@pacamor.com
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 our How-to Guide: Proper Lubrication of Miniature & Instrument Ball Bearings
- See our Shaft and Housing Fits page for a detailed chart and more information line to line, interference & loose fits onto a bearing shaft or into a housing.
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:
– SHORT LEAD-TIMES
Shorten your ball bearing lead times with our domestically produced bearings, manufactured and assembled in Troy, NY.
– COMPETITIVE PRICES
Best prices in the domestic bearing industry!
Reduce your domestic ball bearings costs with our Veteran-American Owned & Operated Small Business.
– RELIABLE QUALITY
Expedite time to market for your new and updated products.
– PROTOTYPE SPECIALISTS
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 – sales@pacamor.com
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.
As quoted in the Automotive World article: End 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. sales@pacamor.com
Authentic PKB Aerospace Bearing at the Pacamor Kubar Bearings factory, in Troy, NY.
Why work with us?
– SHORT LEAD TIMES
Shorten your ball bearing lead times with our domestically produced bearings, manufactured and assembled in Troy, NY.
– COMPETITIVE PRICES
Best prices in the domestic bearing industry!
Reduce your domestic ball bearings costs with our Veteran-American Owned & Operated Small Business.
– RELIABLE QUALITY
Expedite time-to-market for your new and updated products.
– PROTOTYPE SPECIALISTS
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