Coefficient of Friction

The coefficient of friction is a fundamental parameter for applications involving sliding between surfaces or mechanical contact between components. The aluminum oxide formed by anodizing has specific tribological characteristics that can be further optimized through special treatments.

The aluminum oxide produced by anodizing has a coefficient of friction that depends on various factors such as surface finish, the presence of lubrication, the mating material, and operating conditions (load, speed, temperature).

Being a ceramic material, aluminum oxide does not create seizing problems (cold welding) with metallic materials, unlike metal-to-metal couplings, which can exhibit adhesion and cold welding phenomena under load and sliding conditions.

For anodized aluminum oxide in dry conditions:

• Static coefficient of friction: μs ≈ 0.4 - 0.7
• Dynamic coefficient of friction: μd ≈ 0.3 - 0.5

PTFE Variants for Low Friction and Non-Stick Properties

The OX with PTFE variants are designed to achieve reduced friction and improved sliding on anodized aluminum components, limiting typical phenomena such as light seizing and sliding wear. PTFE also provides an effective non-stick effect, particularly useful when surfaces work in contact with plastic films, paper, fabrics, or in the presence of process residues.

The available versions differ according to the anodic base and the thickness of the coating. OX-A-PTFE (approximately 15±5 µm) is suitable when sliding and non-stick properties are required with limited thickness. OX-W-PTFE (approximately 30±10 µm) represents the most suitable solution for precision sliding and applications in the packaging sector, thanks to the combination of a hard base and a finish particularly favorable to sliding. OX-HS-PTFE (approximately 50±10 µm) is instead oriented towards more demanding applications, where high wear resistance on significant thickness is primarily required, while maintaining controlled friction.

From a performance standpoint, the use of PTFE makes it possible to maintain a typical dynamic coefficient of friction on the order of μ ≈ 0.3–0.4, varying depending on the counterface, applied loads, and operating conditions, with improved movement fluidity and a reduced tendency for materials to adhere to the surface.

For more information on PTFE variants and selecting the most appropriate treatment for your application, consult the OX Coatings section or contact Durox technical support.