Just What Is A Lubricant?
By definition, a lubricant is a material by which, when placed between two surfaces that move in relation to one another, its presence reduces or eliminates friction and wear.
Thus, lubricants can be comprised of liquids (oils), semi-liquids (greases), and solids (metals or polymers).
Historically, lubricating oils have been derived from animals, vegetables and petroleum. The animal and vegetable oils were referred to as “natural” being derived from fats, while the petroleum oils were sometimes referred to as “mineral” as in mineral oils or mineral spirits. In the last twenty years, synthetic versions of these oils have become more common and actively promoted for their remarkable chemical stability when exposed to temperature, pressure and time.
Animal-based oils are derived from the purified renderings of the feet and shinbones of various types of cattle. “Neatsfoot oil” is a typical example of this derivation from the shin bones of calves. Thus, it can be seen that these oils are derived from fats. Fats are simply compounds of esters of glycerine and fatty acids.
Prior to the turn of the century, whale blubber was the source of the fats necessary to create the desired oils.
These oils have traditionally been highly prized, having high purity and low viscosity making them ideal for fine mechanisms and even leather tanning.
As with animal-based oils, vegetable-based oils are derived from plant fats—also esters of glycerine and fatty acids. Probably the most common example of a vegetable-based industrial oil is castor oil. Used in a formulation with nitromethane and methanol, it can be recognized as two-stroke engine racing fuel used in motorcycles, go-karts and even model airplanes.
Without question, the most common feedstock for modern oils is petroleum, called in the industry, polyalphaolefins (“PAO’s). Often and erroneously referred to as “fossil fuels” these oils are actually primordial in their origin, a result of exposing the basic elements of hydrogen and carbon to tremendous heat and pressure over long periods of time. Mineral oils are then derived from this petroleum feedstock via fractional distillation.
By definition, true synthetic oils are formulated from small molecules subjected to a chemical reaction. Perhaps the oldest process is known as the “Fischer-Tropsch process” that converts carbon dioxide, carbon monoxide and methane into liquid hydrocarbons. This was, in fact, the process originally developed and used by the Germans during World War II to supplement limited supplies of crude oil.
By taking the short chain hydrocarbons thus synthetically created, and polymerizing them into longer single chain hydrocarbons, synthetic oils with controllable performance characteristics can be created.
While it is easy to focus on synthetic forms of petroleum oils, we would be remiss in not including other forms of synthetics wherein the hydrogen (as in hydrocarbon) is replaced with fluorine (as in fluorocarbon) to produce a synthetic oil most commonly used in vacuum pumps. These fluorocarbon oils (e.g. DuPont Krytox) are exceptionally stable with very low vapor pressures making them ideal for high temperature and low pressure applications such as in aerospace.
By adding a thickener to any of the above-described oils, one creates a grease. A thickening agent serves to retain a film of lubricating oil in proximity to the moving parts thus preventing migration for applications where a constant bath of oil or a reservoir are not practical. Thickening agents come in many forms. Typical examples are:
- Molybdenum Disulfide
Solid lubricants actually fall into three classes. The first being what are called the “dry-lubricants” such as molybdenum disulfide, or graphite. The second is manifested in the form of the metals such as sintered bronze bearings. The third is found in the more modern engineering plastics. Typical examples of engineering plastics that can be used as bearings or wear surfaces are:
- UHMW (ultra high molecular weight polyethylene)
We carry the top watch-maker’s oil formulations. Widely regarded as the top brand and certainly most famous is Moebius of Switzerland. They make a wide range of both natural and synthetic high-purity oils for fine mechanisms, high-quality wrist watches and clocks. The Moebius oils come in a variety of formulations (viscosities) depending upon their intended purpose.
Krytox High Performance Lubricants:
Here you will find a selection of the most common use PFPE greases conveniently packaged in 2 oz. tubes or syringes for easy dispense. These greases and oils are ideal for deep vacuum environments such as aerospace or semiconductor processing. Krytox fluorinated oils are clear, colorless synthetics that are nonreactive, nonflammable, safe in chemical and oxygen service and exceptionally long-lasting.
Greases are thickened with PTFE with a melting point of 617°F and a submicron (0.2 micron) particle size making it ideal for use in bearings. The base oils have vapor pressures below the micro-Torr level making them ideal for deep vacuum applications.
Krytox lubricants are based on fully-saturated synthetic oils containing only carbon, oxygen and fluorine.
- Completely nonreactive—safe for both chemical and oxygen service.
- Odorless, colorless
- Exceptionally wide operating temperature range
- Low vapor pressure is ideal in deep vacuum applications
- Useful operating ranges from as low as -70F up to 550F
The extremely low vapor pressure of PFPE’s produces a family of greases that will not outgas at either high temperatures or low pressures. This family of high performance lubricants includes formulations for the following critical environments:
- Aerospace applications
- Vacuum chamber and semiconductor process equipment applications
- Extreme pressure applications
- Rust inhibited versions
- Food grade
There are three basic types of Krytox PFPE grease from which to choose depending upon desired specific characteristics.
Clean, pure white buttery greases with the same properties as their base oil. A clean, non-staining grease useful for most applications including bearings in vacuum chambers.
These are black greases from the addition of Molybdenum Disulfide for extreme pressure applications such as gearing and heavily loaded bearings.
White greases containing sodium nitrite for corrosion resistance and rust protection.
Each of the three types is further divided into operating temperature ranges with the addition of the following suffixes to the type number:
AZ = -70F up to 300F
AA = -60F up to 350F
AB = -40F up to 450F
AC = -30F up to 550F
AD = -20 up to 550+F