Abstract: A thermokinetic mixer for melt mixing plastics waste includes a housing enclosing a mixing chamber, and a shaft protruding through the mixing chamber and connectable to a drive unit. In the mixing chamber, Y-shaped mixing blades protrude radially from the shaft, wherein the free end of the mixing blades protruding into the mixing chamber is cuboid, and the end opposite the free end of the mixing blades has two legs in each case having at least one through bore. The shaft has polygonal recesses, in which recesses the legs can be fastened by a fastener protruding through the through bores.