What is Fretting Corrosion?
Fretting corrosion is one of the leading causes of connector failure and yet many still remain unaware of what it is or how it can be prevented. Fretting corrosion is the result of micromotion caused by vibration and/or thermal expansion due to heating or cooling cycles. These micromovements wear down through the metal coatings into the base material that then becomes oxidized. As this oxide layer builds up and increases, the oxide film acts as an insulator between the contacts which creates an open circuit resulting in voltage drop across the terminal and ultimately, power failure or signal loss.
To minimize fretting wear and keep oxidation at bay, the implementation of a connector grease is key. Connector grease has two primary benefits:
- The grease reduces physical wear between the connecting surfaces as they undergo micromotions and fretting wear. This helps to preserve the layered coatings on the connectors, designed to prevent oxidation and minimize resistance.
- They insulate the system from the surrounding environment, preventing the build-up of insulative oxide layers which are ultimately responsible for resistance increase and signal loss.
Unlubricated vs. Lubricated Connectors
The difference in fretting wear between lubricated and unlubricated connectors is obvious. Nye engineers built a custom fretting wear test apparatus that monitors the fretting cycles (micromotion) of terminals until resistance increases 100 milliohms over the static baseline.
This allows our engineers to predict the life of terminals when exposed to fretting conditions. A connector lubricated with Nye’s NyoGel® 760G lasted for 6.7 million cycles before 50% failure values were reached compared to unlubricated connectors that only reached .5 million cycles before failure.
Greases Formulated to Fight Fretting
Not all connector greases protect against fretting equally. Nye offers a line of greases formulated with anti-fretting technology to protect against fretting more effectively than other connector lubricants.
| Product | Chemistry | Temperature Range | Fretting Cycles to Failure Point |
|---|---|---|---|
| NYOGEL 760G | PAO | -40 to 135°C | 6.7 Million |
| RHEOTEMP 769G | PAO/AN | -40 to 175°C | 18.7 Million |
| UNIFLOR 8917 | PFPE | -70 to 225°C | 16.8 Million |
*Test Conditions: 2.8mm APEX Copper-Tin Terminals, CTM (10Hz, 100 microns), 50% Failure Values
Visit our Connector page to learn more about grease can reduce insertion force and protect your connectors from wear, environmental corrosion, and oxidation.
