A centrifugal separator facilitates maintenance with a function that provides the user with useful data for investigating the causes of failures and for preventing their recurrence, such as data needed to determine the appropriate management and replacement frequency of consumable parts. The outer layer and inner layer may be transparent to view the electronic device. A second mask is thereafter formed on a surface of the semiconductor substrate. The arrangement comprises further at least two measuring devices for measuring the position of the shoe and means for controlling the position of the shoe based the results obtained by means of the measuring devices so as to be as desired in the direction of nip compression. One end of the elastic arm is angularly connected to the inner plate, and the other end of the elastic arm is defined as a free, and resiliently movable end. An exhaust is provided on the housing for removing and evacuating residue from the end surface area.