Mechanical wear and degeneration of the magnetic properties of magnetic heads caused by the tape

One kind of abrasive wear of magnetic heads is characterized by the generation of a lot of small scratches (typical dimensions: 0.1 ¿m) due to hard particles embedded in the tape. After scratching, the outer head surface is left under a very high compressive stress (up to 3000 N/mm2in ferrites) which greatly change the magnetic properties of the material. This gives rise to a decreasing short-wavelength sensitivity due to a more or less non-magnetic layer on the head surface.