Page 13 - Craft Bearing Catalog
P. 13
Nomenclature Breakdown Lubrication
Bearing Company Inc.
hE mAIN PuRPoSE of lubricating a n Grease
bearing is to coat the rolling contact/
Tload bearing surfaces with a lubricant, Type of Grease – Grease “stays put”, is easy
minimizing direct metal-to-metal contact. This to handle, easy to meter using simple methods,
accomplishes the following: and is helpful in further sealing a bearing from
contaminants and moisture. A widely available,
• Reduces heat, friction and abrasion, prolonging broadly used grease type is NLGI type 2, lithium
useful life, complex based grease with extreme pressure
• Transports heat away from the load zone (oil), additives (EP2). This grease type is available
with various viscosity oils—hydrocarbon as well
• Slows or prevents corrosion, and
as synthetic. Synthetic greases perform well
• Helps reduce the ingress of foreign matter into outside the range of standard hydrocarbon based
the bearing (grease). greases, in both low and high temperatures.
Proper lubrication during assembly is They also have the ability to retain their
critical. Please refer to the assembly instructions lubricating properties for a longer amount of
for lubrication requirements when assembling time over standard hydrocarbon greases. Re-
bearings. Proper lubrication during operation is lubrication intervals can be extended. When
also critical. The type and quantity of lubrication harsh conditions are present or a high degree of
depends on the application—the load, RPM, and reliability is demanded, Craft often recommends
temperature all affect the needed lubrication. The synthetics. For most applications, it is standard
majority (about 90%) of rolling element bearings to use lithium complex, EP2 type grease with
are grease lubricated. Oil is generally utilized in ISO VG 220. A consultation with one of many
high speed and high temperature applications. reputable grease suppliers should yield the right
grease for the job. DO NOT MIX GREASES! The
n Oil variations in additives between brands and types
may cause problems.
When necessary (above 8,000 dn), oil can
be pumped, drained, filtered, cooled and re- Quantity of Grease – More bearings fail
circulated. This is very effective in removing prematurely from over greasing than from grease
heat buildup, prolonging both bearing and starvation. How much grease is required in a
lubricant life. Various types of oil lubrication bearing depends mainly on speed. The amount
delivery methods are available, such as static, of grease to satisfy the needs of particular sizes
constant level oilers, re-circulating, and oil mist and series of Craft bearings is based on the
delivery systems. Various additives are available dn value, the product of which is expressed
to improve resistance to thinning, oxidation as a percentage of a full pack of grease. A full
resistance, corrosion resistance, foaming pack chart for various sizes follows this section.
resistance, extreme pressure properties, etc. As used herein, dn = d (shaft diameter in inches)
Consult with a reputable supplier of oil and x n (shaft speed in revolutions per minute);
grease products to better choose the right for example:
lubricating oil for a particular application.
A 3 /16” bearing rotating 1400 rpm has a dn = 4,813 (3.4375 x 1400) [50% pack]
7
A 4 /16” bearing rotating 1400 rpm has a dn = 6,913 (4.9375 x 1400) [33% pack]
15
A 65 mm bearing rotating 1400 rpm has a dn = 3,500 ([65 / 25.4] x 1400) [75% pack]
A 100 mm bearing rotating 1400 rpm has a dn = 5,600 ([100 / 25.4] x 1400) [50% pack]
Craft Bearing Company, Inc. n Newport News, Virginia n www.craftbearing.com Craft Bearing Company, Inc. n Newport News, Virginia n www.craftbearing.com 11
Craft Bearing 2017 Catalog + Spe11 11 8/14/17 1:51:22 PM
