A Damaging Process on Mechanical Wear of Metallic Thin Film Media

The authors studied processes by which metallic thin film (CoCr/NiFe) type flexible disks are damaged when run against a head. Scratches formed in disk surfaces when run against a head were examined, an ITV camera was used in dynamic observations of surface scratching, scratch tests using a diamond needle performed, and computer analysis were conducted to determine stresses and strains caused by a small foreign object lodged between head and medium. It was concluded that small (several μm), hard objects caught between head and medium may cause large stressing of the metallic thin film and consequent scratching; that strain in the scratched film may cause the medium to bend locally, increasing spacing losses of reproducing signals; and that greater stressing of the metallic film may cause cracking of the latter.