APPARATUS AND METHOD FOR PROCESSING WOOD FIBERS

A refining member including a refining body with a refining surface including first and second refiner bars separated by first and second refiner grooves. The first and second refiner bars extend from respective first and second radially inward positions to respective first and second radially outward positions. The first and second refiner bars have a respective first and second height extending upward from a floor of a respective, adjacent first or second refiner groove. The second height is a minimum height of the second refiner bars and is spaced apart from the second radially inward position, with the second height being at least about 0.35 mm less than the first height. The first refiner bars are adapted to refine wood fibers and the second refiner bars are adapted to break up fiber bundles.