Abstract: The differences in performance of a screening cylinder during screening of a fiber suspension (e.g. low consistency paper pulp) at the inlet end compared to the reject end is accommodated by constructing the feed side surface of the screening cylinder so that it induces greater turbulence in the vicinity of the screen cylinder surface adjacent the reject end of the screen than adjacent the inlet end. Typically this increase in turbulence is at least about 10% (preferably at least about 40%, and typically greater than 100%). The turbulence increase can be provided by a substantially smooth screening medium surface at the inlet end and a contoured screening medium surface adjacent the reject end, or by first and second contoured surfaces of different aggressiveness.

Abstract: The invention relates to a method of manufacturing a screen product and to a screen product manufactured according to the method. In particular, the invention relates to the manufacture of a screen or a filter plate or a cylinder by a new machining method by which a product receives flow properties substantially better than the ones of the prior art devices. It is characteristic of the invention that an aperture having curved wall surfaces is machined in one work phase in the plate in the depth direction. It is characteristic of the screen product of the invention that the screening aperture is progressively widened in the direction of the flow through the plate, and preferably inclined under the ridge adjacent the groove in a plate.