Applied Thermal Fluids

Grease Lubrication – Bearing Grease Lubrication
Krytox Industrial gearbox-oils

Grease Lubrication – Bearing Grease Lubrication

Grease Lubrication – Bearing Grease Lubrication

Why grease lubrication?
Properties
Grease compatibility chart
NLGI Grease consistency grading

Why grease lubrication?

Greases are typically applied in areas where a continuous supply of oil cannot be retained, such as open bearings or gears.  Factors to be considered when selecting a suitable grease are operating temperatures, water resistance, oxidation stability etc. The second factor, not less important, are the grease’s characteristics, including viscosity and consistency.

A lubricating grease consists of a base oil, performance additives and a thickener which forms a matrix that retains the oil in a semisolid state. Most grease thickeners are soaps, i.e. lithium, calcium, or aluminum soap. Complex soap greases have superior temperature resistance and are commonly usable up to 180ºC, at which the mineral oil vaporizes. A smaller number of greases, restricted to very special applications, are manufactured with non-soap thickeners such as organoclays, polyurea or silica compounds.

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Krytox Properties Lubricants Consistency
Krytox Does Not Oxidize

Krytox Properties Lubricants Consistency

Dupont Krytox Properties Lubricants Consistency

Krytox Oil Viscosity

There are two measurements of viscosity: kinematic and dynamic, or absolute viscosity . The viscosity expressed here is kinematic viscosity, the ratio of dynamic or absolute viscosity to density . This is the value usually measured . It can be converted to dynamic viscosity using the following relation:

Kinematic viscosity x density = Dynamic viscosity (Centistokes, cSt x g/cc = Centipoise, cP)

Because of the high density of DuPont Krytox fluids, the dynamic is almost double the kinematic viscosity .

Choosing what viscosity of oil to use depends on the application . Generally, lower viscosity oils flow more readily and are used in operations where high speed is desired. High viscosity oils are preferred for low speeds or heavy loads . Since viscosity drops as temperature increases and rises as temperature decreases, the choice also depends on temperature . Thus, for the same reference temperature, a lower viscosity oil would be preferred for high speed operations and a higher viscosity oil would be preferred for low speeds . This typically applies to choosing a base oil for grease as well .

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Krytox Performance lubricants Characteristics

DuPont Krytox Performance Lubricants Characteristics – Part II

Extreme Temperature Performance

  • Krytox oils and greases are the product of choice in extreme temperature conditions. Most petroleum products begin to degrade above 99 °C (210 °F) and are too viscous at temperatures just below –18 °C (0 °F).
  • Krytox synthetic lubricants have extreme temperature stability, with operating ranges from below –75 °C up to 350 °C (–103 °F to 662 °F) and temperatures up to 400 °C (752 °F) with appropriate metallurgy. Under the D-3336 test conditions of 177 °C (350 °F) and 10,000 rpm, the majority of competing hydrocarbon lubricants fail in less than 1,000 hr.
  • But the general purpose line of Krytox lubricants has been shown to last over 5,000 hr without failure, even at an increased temperature of 200 °C (392 °F). This extreme condition performance is what distinguishes Krytox performance lubricants from other competing products.

Cost Effective of Krytox Performance lubricants 

  • Krytox lubricants are cost effective across a wide range of applications. Due to their inert nature, Krytox lubricants provide a much longer usable life as compared to typical hydrocarbon oils and greases, and the longer usable life allows them to remain for considerable periods of time before needing to be replaced, if they are replaced at all.
  • That translates to savings over time, both by lowering the amount of lubricant purchased and any downtime incurred during relubrication.

Performance Additives of Krytox Performance lubricants 

  • Anti-corrosion additives are combined with Krytox grease to enhance its ability to protect metallic surfaces from corrosion caused by moisture and oxygen.
  • DuPont also offers a patented oil-soluble additive to give the same corrosion protection to our oils.
  • Krytox greases containing anti-wear additives have properties that give high specific load-carrying capacity and the highest protection against wear.

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Chemours Krytox Lubricants Advantage
Chemours Krytox High Performance Lubricants!

Chemours Krytox Lubricants Advantage

Chemours Krytox Lubricants Advantage MIL-G-27617 – Part I

Discovered in 1959, the polymer that would become known worldwide as Krytox showed remarkable thermal and oxidative stability. Potential uses envisioned then included lubricant for the MACH 3+ turbine engine, hydraulic oil, rocket gear box lubricant, and even gyroscope oil.

In 1963, Krytox oil was used in a GE engine test for the supersonic transport aircraft. In 1964, new Krytox PFPE-based grease formulations were developed jointly with the US Navy and the Air Force, resulting in military specification MIL-G-27617, which was developed specifically to cover Krytox. The first commercial sales of Krytox were for non-flammable lubricants for the Apollo space program in 1965.

Prior to 1981, the only commercially available Krytox lubricants were aerospace oil and greases. Since then, PFPE-based oils and greases have been adopted across a very wide range of industries and applications. There are PFPE oils and greases for industrial operations, vacuum pump fluids, incidental food contact, automotive uses, reactive gas, and of course, military applications — to name just a few.

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