Fretting occurs in situation where parts are vibrating or impacting against each other over a very limited contact, so that the relative motion is in the order of 50 to 500µ. This is particularly the case in splines and couplings where motion is transmitted from one part to another via a loaded contact. It can also occur in parts fastened or fitted together where there is a source of external vibration (e.g. heat-exchangers), as well as on bearing housings.

The sequence of events is characterised by:

1. Vibration and sliding
2. Adhesive wear and generation of debris
3. Oxidation of that debris, which remains trapped in the small contact area
4. Abrasion by that debris, with an increased wear rate and even more debris production
5. It results in significant localised damage and sometimes a 'runaway situation.

Fretting Corrosion is the term applied to situations where significant amounts of oxide dust is generated in and around the contact; a characteristic red colour in the case of steel components.

Fretting Fatigue applies to situations where the load and cycles are sufficient to initiate and propagate fatigue cracks, with the onset of failure accelerated by the corrosive element of the wear process.

Fretting is best combated by oxidation resistant coatings (e.g. Electroless Nickel) or softer, ductile self-lubricating coatings like silver or indium. For specific coatings to combat fretting, click below.

• Apticote 350 Polymer composite anodising for fretting with aluminium alloys
• Apticote 400 Electroless Nickel coatings
• Apticote 460 Electroless Nickel/Solid Lubricant composite coatings
• Apticote 600 Silver and Indium coatings
• Apticote Keronite 3000 for fretting with aluminium alloys

Poeton Industries Ltd. Head Office, Eastern Avenue, Gloucester GL4 3DN, England, UK   Tel: 01452 300500  Fax: 01452 500400
Production facilities in Cardiff & Gloucester and in Wisconsin. USA.