A comprehensive engineers' reference source for radial ball bearings and thrust ball bearing




Channeling: If a grease stays in place after it has been displaced by the balls during initial rotation, it is referred to as a channeling grease. This property is useful to reduce torque. A non-channeling grease will tend to migrate back into the raceways, which can promote better lubrication in heavy load applications.

Dropping point: The temperature at which a grease heated in a specified small container becomes sufficiently fluid to drip. Dropping points for common greases are listed in the table of commonly available lubricants. Above the dropping point, a grease will lose its essential characteristics.

Consistency: The consistency of a grease is characterized by its penetration, which is the depth in 1/10th millimeters that a standard cone sinks into the grease under prescribed conditions. High numbers indicate softer grease, since the cone has sunk further. Grease may change consistency once it is worked (kneaded), so penetration levels are referred to as worked or unworked. If a grease has a uniform consistency, then there will only be a small spread between the worked and unworked values. Channeling greases tend to be thicker, so will have lower penetration values. Specific penetration values are available from grease manufacturers (ranging from approximately 100 to 400 x 1/10th mm).

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).

50% (+/-5%)
30% (+/-5%)
20% (+/-5%)

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

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