should operate at a gap of between 3 and 5 mm when the outer rings are at a standard operating gap the gap 158 at the inlet of the outer rings should be slightly larger than the gap at the outer part of the inner rings the outer part of the inner ring is preferably ground with taper which ranges from flat to approximately 2 degrees depending on application larger tapers and larger operating gaps will reduce the amount of work done in the inner rings the construction of the outer region of the inner ring is such that it should minimize impact on the feed material in order to preserve fiber length at a maximum while properly separating fibers the groove width in the fibrating region 110 should be smaller than the wood particles and in order of magnitude of minimum operating gap for the fibrating region typically no groove should be wider than 4 mm wide this ensures that wood particles are being treated in the gap rather than being wedged between bars and hit by bars from opposing disc in the fibrating inner region 110 or plate inlet for a one piece refiner plate the chips are reduced to fibers and fiber bundles before passing through annular space 160 and entering the outer ring 104 that ring can closely resemble known high consistency refiner plate.