Yearly Archives: 2019

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  

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.