FrettingWear

FrettingWear is a form of wear produced by small-amplitude oscillatory relative motion at contact interfaces under load, leading to surface damage and debris. It is common where components experience repetitive tangential forces such as joints, fasteners, pivots, bearings, and dental implants.

Mechanism: The motion causes micro-slip, high local contact stresses, frictional heating and oxide layer disruption. Repeated cycles can initiate surface cracks and remove material, with corrosion potentially exacerbating the damage when the environment is oxidizing. Wear patterns include pitting, furrows, and transfer layers. The wear rate depends on load, stroke amplitude, frequency, lubricant presence, roughness, temperature, and material compatibility.

Evaluation: Fretting wear is studied with specialized fretting tests that apply controlled normal load and oscillatory tangential displacement. Measurements include wear rate via mass loss or profilometry, friction, and crack initiation. Wear maps and contact-stress analyses help predict regimes: slip, mixed, or partial slip. Debris and coating integrity are important outcomes; fretting can also accelerate corrosion.

Mitigation and materials: Solutions include increasing preload to reduce slip, selecting materials with compatible hardness and ductility, applying coatings (hard coatings, DLC, ceramic, or oxide layers), using lubricants or dry-film lubricants, improving surface finish, and designing geometries to reduce contact stress and micro-slip. In aerospace and mechanical assemblies, fretting wear must be considered in maintenance planning; in implants, biocompatibility and wear debris control are important.