The present invention provides an apparatus and a method for coating small Nd—Fe—B magnets. The apparatus includes a furnace having a roller including at least one stirring piece disposed in the compartment. The stirring pieces have an isosceles triangle or trapezoidal shaped cross-section. The side wall of the furnace defines an inlet aperture and an outlet aperture disposed diametrically opposed to one another. A plurality of target source holders include two first target source holders and two second target source holders disposed on the side wall and spaced from one another and between the inlet aperture and the outlet aperture. The method includes a step of disposing a plurality of conductors with the small Nd—Fe—B magnets in the compartment of the roller. The small Nd—Fe—B magnets are mixed with the plurality of conductors in the roller with the roller being rotated of between 5 rpm and 20 rpm.