Abstract: A carding machine includes clothed rolls for processing and carrying fiber material thereon; an arrangement for separating lightweight waste from the fiber material processed by the clothed rolls; a conduit for receiving the lightweight waste; an air stream generating arrangement for generating an air flow in the conduit for removing the lightweight waste; an adjusting device for varying a degree of carding intensity of the carding machine; and a detecting device for measuring quantities of the lightweight waste produced at a respective degree of carding intensity.