On the attraction force applied on metal pieces in a traveling wave conveyor

The traveling wave conveyor (TWC) which is generally used for moving high-resistivity particles is employed in this paper to analyze a magnetic attraction force applied on nonferrous metal pieces. A planar three-phase conveyor, constituted of parallel electrodes supplied by high voltage amplifiers controlled by digital function generators, has been used for analyzing the attraction force applied on 15 mm × 15 mm square metal pieces made of copper, bronze and steel. The TWC is supplied by three high voltage amplifiers (2 kV, 20 mA) and fixed on a mechanical device allowing its manual inclination from 0° (horizontal; initial condition) up to an angle of 180°. The intensity of the force is then estimated by measuring the drop angle for which the metal piece detaches from the surface of the conveyor. The obtained results have shown the existence of an electromagnetic force that depends on the frequency and the amplitude of the applied voltage. Based on this force, two new separation techniques of mm-size metal/plastic granular mixtures were proposed and tested succefully.