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 Lubrication (continued) __________________________________________________________________
Other factors: :Grease manufacturers supply a wealth of information on their products. Measured parameters include oil separation %, oxidation stability, evaporation loss %, and particulate content by size. Dynaroll can supply manufacturers' specification sheets upon request.

Percentage fill: The percentage fill of a grease is the ratio (as a percentage) of the actual grease volume to the total available volume for the grease between the bearing raceways. A 20-30% percentage fill is considered normal for small bearings, although fills as low as 10% may be used where the load is low and low torque is a requirement, especially for channeling greases. The percentage fill of a bearing is a purchasing specification (see Dynaroll part numbering system).

DYNAROLL LUBRICATION CODE
PERCENTAGE FILL
S
50% (+/-5%)
L
30% (+/-5%)
K
20% (+/-5%)

Note: In some cases, lubricant quantity may be specified by weight. Contact Dynaroll for more information.


LUBRICATION METHODS

Grease (standard): Grease is deposited between the balls in the bearing raceways in carefully controlled clean conditions, according to the specified quantity. Bearings are not normally rotated after this process, so that run-in is necessary to distribute the grease evenly.

Oil (standard): Oil is deposited in the bearing raceways in carefully controlled clean conditions. Normally, oil quantity is not specified by the user, but is factory determined according to bearing size. In some cases a specified weight of oil can be used. Contact Dynaroll for more information.

Centrifuging: For torque sensitive applications, centrifuging may be specified to remove excess oil, leaving a
very thin film.

Vacuum impregnation: If the bearing retainer (cage) is made from a porous material, then vacuum impregnation can be used to force lubricant into the pores, providing an oil reservoir. When a porous retainer is used with grease, then the cage may be impregnated with the base oil to prevent leaching from the grease.

Plating: Bearings may be immersed in an oil or grease that has been diluted with a carrier solvent. When the carrier evaporates, the bearing surfaces are completely coated with a small amount of the original lubricant which acts both as a corrosion shield (if applicable) and a lubricant where only a very small amount is required (e.g. for low torque). The choice of solvent must be compatible with the base lubricant. Contact Dynaroll for more details of the plating process.

Dry (no lubricant): Bearings may be specified without any lubricant. However, they may be susceptible to corrosion. Bearings made from 52100 chrome steel are always supplied with a coating of corrosion-inhibitor (even when supplied “dry”), since, without this coating, corrosion would be rapid and unavoidable.