Measure flatness

Measuring the flatness of surfaces is of great importance in various applications. Some examples are the testing of sealing surfaces between two bodies, such as the cylinder head gasket in automobiles. Measuring flatness is also an important factor in the production of preliminary products in the metal industry, such as the production of axis guides for measuring systems, or in the production of wafers in the semiconductor industry.

Definition flatness

Flatness is the difference between the highest and lowest points of a surface located between two ideal flat (planar) surfaces. The distance between the two planar surfaces defines the flatness tolerance.

In the real world, flatnesses of a few nanometers can be achieved, e.g. for highly polished flat glass surfaces. For metallic measuring objects, which are manufactured in large quantities using the usual production methods, flatness tolerances of a few µm to a few tenths of a mm are common.