What are dry film lubricants, and what are they used for?

What are dry film lubricants?

Dry film lubricants or solid film lubricants are materials that reduce friction between surfaces. Ideal for use in extreme environments, including high and low temperature, high and low pressure, and where liquid and oils need to be avoided.

Dry film lubricants are an attractive alternative to fluid lubricants because they minimise friction and prevent seizing and galling, especially in extreme applications where fluids may freeze or vaporise. For instances where traditional lubricants, like oil or grease, can undergo a state change (i.e. freeze) and thus no longer provide protection, a dry-film lubricant will remain intact and provide continuous lubrication and protection.

How do dry film lubricants work?

There are two main types of dry-film lubricants, which are known as crystalline lattice (lamella) type structures such as Molybdenum Disulphide, Tungsten Disulphide and Graphite(DRY MOLY, DRY GRAPHITE SPRAY, etc) and Fluorocarbons such as PTFE (DRY PTFE).

In crystalline form structures such as DRY MOLY and DRY GRAPHITE, the shear forces between opposing layers are weak resulting in lubricity between sliding surfaces.

Fluorocarbon containing dry lubrications, like DRY PTFE are uniquely capable of resisting attack from another chemical structure, as well as have extraordinary bond strength. Additionally, it has the ability to repel other atoms at a molecular level, which in combination gives DRY PTFE its ultra-low coefficient of friction and superior chemical resistance.

What are dry film lubricants used for?

There is a wide variety of applications for dry film coatings, some of which include:

Fasteners, springs bearings, cams, gears and seals
Aerospace hydraulic fittings, valve components and non-intrusive medical instruments
Shafts, splines and bushes
Rubber and other non-metallic substrates
Saw blades and secateurs
Automotive fasteners, seat slides and rails
Petrochemical, oil and gas subsea and topside components

Dry-film lubricants are useful in conditions where conventional lubricants are inadequate.

One such example is where reciprocating motion is present. A standard application of dry-film lubricant could include where a sliding or reciprocating motion that requires lubrication to minimise wear is present. An example of this use can be observed in gear and change lubrication. Liquid lubricants will squeeze out while solid lubricants will not escape interlocking or reciprocating parts.

Dry-film lubricants can also be used in ceramic applications for cases where chemically active lubricant additives have not been found for a particular surface, such as polymers or ceramics.

Also, the benefits of dry-film lubricants can be applied to instances where lubrication is required in a high-temperature environment or where there is an oxidising atmosphere. Liquid lubricants such as oil and grease will typically not survive these conditions.

Furthermore, where extreme contact pressures are present, dry-film lubricant provides a high bearing-load combined with a low shear stress due to the lamellar structure of the lubricant.