Control of fiber treatment

The invention relates to a method for controlling a device for treating high-consistency fibrous material (1) with a housing (2) in which a first treatment tool (3) and a second treatment tool (4) are arranged， the treatment tools (3， 4) are each attached to a base plate (7， 8)， have a rotationally symmetrical shape， are arranged coaxially to one another， rotate relative to one another about a common axis (5) and delimit a treatment gap (6) through which the fibrous material (1) flows radially， the gap width of which can be changed via an axial displacement of at least one base plate (7， 8) of a treatment tool (3， 4). Safe and efficient operation of the device is to be made possible with relatively simple means by determining the minimum distance (see M) between the base plates (7，8)， the vibrations on the device are detected and the distance (s) between the base plates (7，8) rotating relative to each other is reduced until the frequency (f) and / or the amplitude and / or the change in frequency (Δf) and / or the change in the amplitude of the vibrations exceeds a limit value and the distance (s) as a minimum distance when the limit value is exceeded (seeM) is determined.