UNDERSTANDING DRY-FILM VS. OIL LUBRICANTS
AND WHEN TO USE THEM

Applications for lubricants are endless and it is important to know when best to use a dry-film lubricant over an oil-based lubricant or vice versa. Factors to consider include: re-lubrication cycles, temperature limitations, life expectancy, surface area, and environments (outdoors vs. closed-conditions). Let's start with differentiating the two.

Oil film or wet lubricants are traditional oils and greases common to the market that are usually very easy to apply. Oil lubes manage friction extremely well under ambient and closed conditions. Depending on temperature, they provide the best coefficient of friction out of all the lubricants. Because they are liquid in nature, the lubricant can flow and migrate to very hard to reach places like chain linkages to provide relief from stress and wear. They are recommended for use in enclosed environments in order to avoid attracting and trapping particles such as sand, dirt, dust, and other foreign airborne debris. Once trapped, these contaminates will increase friction to cause excessive wear, increase noise, and produce thermal build-up resulting in premature part failure. Although messy, oil lubricants are preferred for controlling high friction situations and penetrating deeply into small crevices.

Dry film lubricants are solid lubricants such as graphite. They are wet when applied, but quickly dry to form a slippery and durable coating. These products are typically painted on to the surface by brush, spray, or aerosol application. Graphite is widely used in the market as a dry lubricant because of its unique flat molecular structure allowing it to easily slide with itself like a deck of cards. Other dry lubricants are available in the marketplace, but they are typically more expensive.

There are several reasons someone would choose oil lubricants over dry lubricants. Again, oil lubrication works best for applications that require a very low friction. The coefficient of friction of dry lubricants will be higher than petroleum-based lubricants. Because of its ability to flow, oil lubricants can easily migrate to different areas of the part. Very light oils or low viscosity oils can reach into very difficult to reach places. Once applied, the effects are very immediate.

On the other hand, dry film lubricants are preferred under certain conditions due to their properties as a solid. Dry film lubricants will wear away over time but at a much slower rate compared to oil based lubricants. Since a dry film lubricant can adhere like a paint, the lubricant is bonded to the surface making it difficult for water to simply wash away. Oil lubricants can float to the surface in the presence of water because of its lower density to point that the part can be without lubrication.

Another advantage of dry lubricants is that it will not attract and trap dust, grit, sand, dirt, mud that can lead to increased friction and part failures. Just think of throwing some sand on a surface coated with oil and another with a dry lube. Which one would the sand stick to? For this reason, dry lubricants are ideal to create slippery non-stick surfaces.

In the case of SLIP Plate¨ products, the solid film of graphite lubricant will perform under temperature extremes. Once dry, the material will not change consistency in response to the outside weather temperature. Graphite is also a hydrophobic material. Simply put, it means that graphite is naturally water resistant and therefore, rain and snow easily repels from its surface making it ideal for outdoor environments.

Graphite is a natural mineral lubricant made of carbon and is an environmentally conscience alternative to petroleum-based wet film lubricants. While there are more eco-friendly oil-based products being introduced into the marketplace daily, traditional oil based lubricants still dominate the marketplace. These oils are typically synthetic and very difficult to break down in nature.

Key Factors to Consider When Choosing a Lubricant

Summary Table	Dry Film Lubricants	Oil Lubricants
Friction Management	Slightly higher coefficient of friction. Provides a longer consistent lubrication over time. Material does not typically change over time. Will not attract dust, dirt, and debris. These elements simply will blow off surface.	Lower coefficient of friction. Will degrade or breakdown easily over time. In an open environment, can attract dust, dirt, and debris over time. This can create a paste and significantly lower the coefficient of friction and become potentially abrasive. Cleaning and re-application will be required depending on the environment.
Temperature	Because it is a solid, it does not change performance with ambient temperatures. Graphite lube breaks down thermally at extremely high temperatures (450°F). Handles very low temperatures (-75°F).	Because it is a liquid, it will change performance as the viscosity under low and high ambient temperature conditions. Material can thermally break down in ambient temperatures.
Flow	Does not easily flow into small areas. Adheres to the surface securely. Requires much effort to remove it from the surface.	Easily can flow into small areas for good lubrication, but can flow off the surface easily. This means that the product will need to be re-applied more often. Material can thermally break down in ambient temperatures.
Reactivity to Water	Material is hydrophobic. Lubricant is typically bonded on tightly to the surface. Difficult to wash off.	Material is hydrophobic. Water can displace the oil lube and easily be washed off the surface.
Environmental	Graphite lubricants are mainly carbon and natural to earth in its usable state.	Petroleum based lubricants are typically synthetic and can cause environmental harm.

Thus, a dry film lubricant remains dry to provide a more consistent friction management system, giving a longer lasting anti-friction surface, and extending the life of mechanical parts regardless of the change in ambient temperatures. As a natural mineral made of carbon, graphite is a very environmentally friendly lubricant. Oils can provide a better anti-friction surface and easily flow into very hard to reach places.

Choosing the right lubricant can extend the life of your devices, prevent a mess, and reduce re-application. A little research can offer you a great return in terms of maintenance and efficiency.

Article and information courtesy of Superior Graphite.