The working principle of The fourth generation mental magnetic liners: Since the magnetic field of the liner, the mill work, the work on the adsorption layer of liner debris ore grinding media and the magnetic particles to form a protective layer, so that the wear liner surface from direct to magnetic liner given instead of high manganese steel liner companies will bring huge economic benefits. Component: Metal magnetic liner is composed of a metal body (shell), permanent magnet (cover polyaddition magnet), the elastic layer of three parts. Circuit design using a ball mill liners in the cylinder, the end cap to the circumferential direction of the N-S poles alternately arranged, is an open-type magnetic system.