The lubricating oils used
in various kinds of internal combustion engines (automobiles, boat, airplanes,
grass cutter, mist blower, water pump, etc) are generally referred to as engine
oils (or motor oils). One of the most important properties of engine oil is its
viscosity, where it must be high enough to form an effective lubricating film,
but low enough to be able to coat the engine parts properly under all conditions.
Engine oils with different viscosity ranges are generally divided into single-
or multi-grade, categorised by SAE numbers. Engine oils are further categorised
by other standards (API, ILSAC, etc) based on their performances, in terms of
anti-oxidation, anti-wear, detergence, foaming and other properties.
Greases are commonly used where
the lubricant is required to stick to the contacting surfaces, or where high pressure
is present. Many types of greases are available. They range from the calcium-based
for general use, to the lithium-based for applications that require better moisture
resistance and higher temperature, and the molybdenum-based for extreme conditions.
The use of water soluble
coolant in modern automated machine tools, especially the CNC machines, is growing
rapidly. These coolants are normally delivered at high pressure and flow rate.
It is hence important for the slideway oil used to provide a film with excellent
lubrication characteristics to minimise the ¡°stick-slip¡±
problem, and yet exhibit good adhesion property to minimise the ¡°wash-off¡±
effect. It is also desired for slideway oil to have rapid demulsification ability
which allows tramp oil to be easily skimmed off for extended coolant life. Other
important properties of slideway oil are excellent anti-corrosion and anti-wear.
Gear oil is specially designed
for use in transmissions, differentials and transfer cases. Its viscosity is typically
higher because most of these devices do not have pumps for transferring the oil.
The higher viscosity ensures that the lubricant from the lower portion of the
gears bathed in the oil sump to be carried and transfer throughout the gear train
when the gears rotate. EP and anti-wear additives are common ingredients to provide
good protection for the gears.
Hydraulic systems are
designed based on the principle of Pascal¡¯s law, where energy can
be transferred from one point to another through the hydraulic fluid. Selecting
a fluid with the right viscosity is therefore important in a hydraulic system,
which depends on fluid flow for energy transmission. Hydraulic oil is also required
to lubricate and protect the internal component of the hydraulic system, requiring
the oil be formulated with good anti-wear and anti-corrosion properties.
Compressors are machinery
that elevates the pressure of a compressible medium, normally air, and other types
of gases. The most common compressors are the reciprocating and rotary types.
In most of the applications, petroleum-based lubricants which exhibit high level
of oxidation stability, wear protection and demulsification ability are excellent
Auto Transmission Oil
of automatic transmission systems are under continuous improvement for increased
durability and efficiency. These changes would require the transmission oil to
operate under tougher conditions such as elevated temperature. It is imperative
that the auto transmission oil is required to possess superior thermal, chemical
and oxidation stability. The two most common categories of auto transmission oils
used today are classified under Dexron and Mercon.
Cutting oil, or commonly
known as coolant, is used to lubricate and cool the cutting tools and the pieces
they are operating on. In order to achieve the increased requirements of high
production yield, and to address the safety and environment issues, the use of
water soluble cutting oils is gaining popularity.