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LUBRICATION

12.3 Lubricants Table 12.2 Grease Properties

12.3.1 Lubricating Grease Name Lithium Grease Sodium Grease Calcium Grease Mixed Base Complex Base Non-Soap Base Grease
(Popular Grease Grease (Non-Soap Grease)
Grease is a semi-solid lubricant consisting of base oil, name) (Fiber Grease) (Cup Grease)
a thickener and additives. The main types and general (Complex Grease)
properties of grease are shown in Table 12.2. It should
be remembered that different brands of the same type Thickener Na + Ca Soap, Ca Complex Soap, Urea, Bentonite, Carbon Black, Fluoric
of grease may have different properties. Li + Ca Soap, Al Complex Soap, Compounds, Heat Resistant Organic
Li Soap Na Soap Ca Soap etc. Li Complex Soap, Compound, etc.
(1) Base Oil etc.
Base Mineral Oil Diester Oil, Silicone Oil Mineral Oil Mineral Oil Mineral Oil Mineral Oil Synthetic Oil (Ester Oil,
Mineral oils or synthetic oils such as silicone or diester Oil Polyatomic 170 to 210 70 to 90 Mineral Oil Polyatomic Ester Oil,
oil are mainly used as the base oil for grease. The Ester Oil 160 to 190 Synthetic Hydrocarbon
lubricating properties of grease depend mainly on the Properties Oil, Silicone Oil, Fluoric
characteristics of its base oil. Therefore, the viscosity Based Oil)
of the base oil is just as important when selecting
grease as when selecting an oil. Usually, grease made Dropping 170 to 195 170 to 195 200 to 210 180 to 300 > 230 > 230
with low viscosity base oils is more suitable for high Point,°C –20 to +110 –50 to +130 –50 to +160
speeds and low temperatures, while greases made –20 to +130 –20 to +60 –20 to +80 –20 to +130 –10 to +130 < +220
with high viscosity base oils are more suited for high Working 70 100 60
temperatures and heavy loads. Temperatures, °C Good Good Good 70 40 70 70 70 40 to 100
However, the thickener also influences the lubricating Fair Fair Poor
properties of grease; therefore, the selection criteria for Working Good Good Good Poor Good Good Good Good
grease is not the same as for lubricating oil. Moreover, Speed, %(1)
please be aware that ester-based grease will cause Fair Poor Fair to Good Fair to Good Fair Fair
acrylic rubber material to swell, and that silicone-based Mechanical Good
grease will cause silicone-based material to swell. Stability Poor Good Poor for Na Good
Soap Grease
(2) Thickener Pressure Poor to Good Fair to Good
Resistance Fair to Good
As thickeners for lubricating grease, there are several Long and short Suitable
types of metallic soaps, inorganic thickeners such as Water Resistance Good fiber types are for extreme Good Good
silica gel and bentonite, and heat resisting organic available. Long pressures
thickeners such as polyurea and fluoric compounds. Rust Prevention Good Good Poor fiber grease is mechanically Fair to Good Fair to Good
The type of thickener is closely related to the grease unsuitable for stable
dropping point (1); generally, grease with a high General Good low Mainly for high high speeds. Extreme pressure Often used for Mineral oil base grease is middle
dropping point also has a high temperature capability purpose temperature temperature Attention to grease containing roller bearings and high temperature purpose
during operation. However, this type of grease grease used and torque applications. water and high high viscosity and large ball lubricant. Synthetic oil base grease
does not have a high working temperature unless for numerous characteristics. Unsuitable temperature is mineral oil and bearing. is recommended for low or high
the base oil is heat-resistant. The highest possible applications Often used for for bearings requred. extreme pressure temperature. Some silicone and
working temperature for grease should be determined small motors for high and additive (Pb fluoric oil based grease have poor
considering the heat resistance of the base oil. Remarks and instrument low speeds or soap, etc.) has rust prevention and noise.
The water resistance of grease depends upon the type bearings. Pay heavy loads or high pressure
of thickener. Sodium soap grease or compound grease attention to those having resistance.
containing sodium soap emulsifies when exposed rust caused numerous
to water or high humidity, and therefore, cannot be by insulation sliding-contact
used where moisture is prevalent. Moreover, please be varnish. areas (roller
aware that urea-based grease will cause fluorine-based bearings, etc.)
material to deteriorate.
Note (1) The values listed are percentages of the limiting Remarks The grease properties shown here can vary between brands.
Note (1) The grease dropping point is that temperature speeds given in the bearing tables.
at which a grease heated in a specified small
container becomes sufficiently fluid to drip. Table 12.3 Consistency and Working Conditions

(3) Additives Consistency 0 1 2 3 4
Number
Grease often contains various additives such
as antioxidants, corrosion inhibitors, and extreme Consistency(1) 355 to 385 310 to 340 265 to 295 220 to 250 175 to 205
pressure additives to give it special properties. It is 1/10 mm
recommended that extreme pressure additives be
used in heavy load applications. For long use without Working ·For centralized ·For centralized ·For general use ·For general use ·For high
replenishment, an antioxidant should be added. Conditions oiling oiling temperatures
(Application) ·For sealed ball ·For sealed ball
(4) Consistency ·When fretting is ·When fretting is bearings bearings ·For grease seals
likely to occur likely to occur ·For high
Consistency indicates the “softness” of grease. Table temperatures
12.3 shows the relation between consistency and ·For low
working conditions. temperatures

Note (1) Consistency: The depth to which a cone descends into grease when a specified weight is applied, indicated in units
of 1/10mm. The larger the value, the softer the grease.

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