Douris , Ê et al. December 5, 2000 Abstract An extruder screw having at least one raised part forming a thread projected on a core intended to be rotatably mounted inside an extruder roll in which the raised part includes a crown wall and side walls intersecting with the crown wall, the intersections between each of the side walls and the crown wall forming edges intended to cut the material, the crown wall of said raised part being provided with a coating of at least two materials of different hardnesses placed side by side on the crown wall.
