Performance Lubricants
New Bearing Preparation with Krytox™ Lubricants

Product Information
Before You Start
Dirt is one of a bearing’s worst enemies. That’s why it is
so important to work in a clean area, with bearings andlubricants covered until ready for use. When handlingbearings, wear clean elastomer gloves and use clean,lint-free rags. Compressed air, if used, should be filteredand dried. Do not spin a bearing with compressed air.
Even though a bearing might not have grease or oil in it, it
will have anti-rust preservatives that will prevent properadhesion of Krytox™ lubricant, and the preservatives must
be removed before filling the bearing.
Before adding Krytox™ grease to a bearing, the bearing
should be cleaned of all existing greases, oils, orpreservative oils used to protect it during storage. If left
in the bearing, these hydrocarbon oils can form carbon
deposits at higher temperatures that may acceleratebearing failure.
1. Cleaninga. Remove the seal by carefully prying between it and theinner ring. Care should be taken to prevent the prying
tool from coming in contact with any race pathway, thecage, or the rolling elements of the bearing. Shields
normally cannot be removed from a bearing withoutcausing damage; so, they are typically not goodcandidates for a lubricant change.
b. A standard parts cleaner/washer can be used toclean the grease and/or rust preventative from thebearings. Aqueous or solvent based fluids including
non-chlorinated brake parts cleaner can be used.
Chlorinated solvents should be avoided, because
they can leave chlorine that can cause corrosion.
Fluorinated solvents will not work for the removal ofhydrocarbon lubricants. If an aqueous based cleaning
fluid is used the parts should then be rinsed with ahigh flash solvent. If the parts cleaner is heated, thetemperature should be maintained below the flash
point of the solvent. Do not allow the solvent to get
too contaminated, as cleaning effectiveness will
be reduced. Follow proper precautions and safetymeasures for the corresponding solvent/cleaner used.
c. Dry the bearings by circulating warm air through thebearing or by heating to 93.3 °C (200 °F) for 10
minutes. Allow to cool to room temperature. The metalmust be completely dry of all solvents, or the grease
might not adhere properly and could cause the bearing
to fail prematurely. Volatile solvents can also be used
as a final rinse to remove heavier solvents, for speed
drying, and to ensure the bearing is completely clean.
However, volatile solvents are more flammable; so,caution must be used when handling them.
After the bearing surfaces are clean, they should belubricated/wiped with Krytox™ lubricant and properly
stored to prevent corrosion.
2. Repacking
a. Cleaned bearings should be lubricated immediately
with the specified lubricant. Rolling elements may
be pre-lubricated with Krytox™ oil that has the same
viscosity as the base oil in the grease. Lubricate eachrolling element with a drop of oil and slowly rotate witha slight thrust by hand, so that the elements rotate toevenly spread the oil.
b. The correct amount of grease should be weighed ona gram balance and transferred to a clean syringe.
Remember that the specific gravity of Krytox™ grease isabout 2.0 mg/L, and fill by volume rather than by weight.

Krytox™

Performance Lubricantsc. Once the syringe is packed with the correct amount oflubricant, inject half of the grease equally in each of thecavities between the rolling elements, from one side of
the bearing. Repeat, using the remaining grease on theother side of the bearing.

Because Krytox™ grease is heavier than hydrocarbon
lubricants, its higher density must be considered when
determining the fill quantity by weight. Consult yourbearing manufacturer for the capacity of the specificbearing you are using.

d. Rotate the bearing slowly by hand to spread anddistribute the lubricant. Enough thrust should beapplied by hand to cause the rolling elements to rotate.

To ensure that another type of grease is not accidentally
put into the bearing, grease fittings should be changed
to a different style, such as button-head or pin type. A
dedicated grease gun that matches the fitting should
be used.

e. Replace seals or shields carefully to avoid causing
damage that would allow the grease to leak out
prematurely.
How much grease to put in a bearing?
Proper lubrication is achieved by using the correct
amount of grease. Too little grease in the bearings causes
premature failure. Too much grease at the initial fill orduring re-lubrication can cause overheating of bearings
that are running at medium to high speed, resulting inbearing failure. The amount of grease put in the bearing
depends on the application and operating speed.
• For applications such as conveyor rollers and lowspeed machinery with DN values (inner race ID in mm xrpm) below 50,000, the bearing can be filled to about
60–75% of the free volume.
• For medium-speed applications, i.e., DN 50,000 to200,000, the bearing can be filled 35–50%.

Speed Factor
The speed factor (DN) indicates the permissible speed
range for grease in a rolling bearing. The DN value is theinner race i.d. in millimeters multiplied by the RPM. DNvalues of 100,000 to 400,000 and higher have beenachieved at temperatures of 204 °C to 260 °C (400 °F
to 500 °F) in actual field service using Krytox™ greases. Atvery high speeds, a special break-in run might be needed
to spread the grease to avoid overheating.
The speed factor is affected by the base oil type, inaddition to viscosity and thickener type, and is a measureof the lubricant’s internal friction. The limiting speed
for grease-lubricated rolling bearings is dependent
on the type of bearing, its load, speed, precision, andlubrication system.

• For higher-speed systems, the fill is typically 25–35%.
• Some extreme-speed special applications have grease
fills of only 10–15% (see Speed Factor for definition of
DN values).

The information set forth herein is furnished free of charge and based on technical data that Chemours believes to be reliable. It is intended for use by persons having technical skill, at theirown discretion and risk. The handling precaution information contained herein is given with the understanding that those using it will satisfy themselves that their particular conditions of use
present no health or safety hazards. Because conditions of product use are outside our control, Chemours makes no warranties, express or implied, and assumes no liability in connection withany use of this information. As with any material, evaluation of any compound under end-use conditions prior to specification is essential. Nothing herein is to be taken as a license to operate
under or a recommendation to infringe any patents.

© 2023 The Chemours Company FC, LLC. Krytox™ and any associated logos are trademarks or copyrights of The Chemours Company FC, LLC. Chemours™ and the Chemours
Logo are trademarks of The Chemours Company. .

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For product information, industry applications, technical assistance, or global distributor contacts, visit krytox.com or within theU.S. and Canada, call 1-844-773-CHEM/2436 or outside of the U.S., call 1-302-773-1000.

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NO PART OF THIS MATERIAL MAY BE REPRODUCED, STORED IN A RETRIEVAL SYSTEM OR TRANSMITTED IN ANY FORM OR BY ANY MEANS ELECTRONIC, MECHANICAL, PHOTOCOPYING,RECORDING OR OTHERWISE WITHOUT THE PRIOR WRITTEN PERMISSION OF CHEMOURS.