what is abrasion?

What exactly is abrasion? For many products, it is easy to identify something that is worn. But understanding how it got to that state is not as simple! ASTM International defines wear as "damage to a solid surface (generally involving progressive loss of material), caused by the relative motion between that surface and a contacting substance or substances". In most instances, the material removal is a gradual process and the motion is a repetitive action.

Wear is a complex phenomenon that is influenced by many parameters. These include, but are not limited to:

• contact geometry
• length of exposure
• interacting material surfaces
• normal force
• sliding speed
• environmental conditions
• material composition and hardness

Depending on the materials involved, the product and/or contacting surfaces may appear to be relatively smooth. In actuality, there are asperities that form the contact junctions of the materials. Similar to the peaks and valleys shown in the diagram, these asperities support the load and tend to deform when the surfaces slide over one another. With repeated movement, material is eventually removed from one or both surfaces.

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