Surface Analysis: Beyond Roughness

Most discussions on the quality of surface finish revolve around the measure of roughness. Indeed, roughness is the most common measure of surface finish, and parameters such as average roughness (Ra) and mean roughness depth (Rz) are the most commonly specified. But the ways to measure a surface and the reasons for doing so go far beyond roughness.

In fact, many experts choose to use the terminology of "surface texture" rather than simply calling these characteristics "roughness."

Some measurements determine how a surface will bear loads, while others determine how well a surface provides a seal against leaks, either with gaskets or through direct contact. Some surfaces can be made to retain lubricant or adhere a coating.