Inspection can occur during or after the manufacturing process.
The images shown below are from an armature of a used fractional horsepower electric motor and highlight its commutator. The commutator must have a smooth, defect-free surface that is concentric with the armature's shaft to provide efficient, reliable and quiet motor operation. A highly compressed image of a commutator of a typical part is shown below. Small defects that could readily escape notice by human inspectors were readily detected on uncompressed images. The previous image is a 360 combination End View and Top View of the commutator.