Waviness is the measurement of the more widely spaced component of
surface texture. It is a broader view of
roughness because it is more strictly defined as "the irregularities whose spacing is greater than the roughness sampling length". It can occur from machine or work
deflections, chatter,
residual stress,
vibrations, or heat treatment. Waviness should also be distinguished from
flatness, both by its shorter spacing and its characteristic of being typically periodic in nature.