Screw shaft surface

Screw press, preferably for removing liquid from a material to be conveyed, comprising a screw shaft complete with a helical conveying flight mounted on the screw shaft and a housing shell surrounding it, where a transport channel is formed for the material to be conveyed between the screw shaft, the conveying flight, and the housing shell. In order to prevent conveyed material components from adhering to the screw shaft, and thus uneven filling of the transport channel, the invention provides for the screw shaft to have a surface profile, at least in one section of the transport channel.