Micro/nanoscale tribology of linear tape drives.

摘要

To increase storage capacity, future high performance linear tape systems will require the use of smoother and thinner magnetic tapes, lower head-tape spacing, lower track width, and higher track densities. In the case of magnetic tapes, smoother surfaces lead to increased static/kinetic friction, and low flying heights lead to partial contact between the head and the tape both of which result in the head and the media degradation and failure due to tribological aspects. Miniaturization of magnetic recording heads requires better understanding of wear mechanisms on a nanometer size scale. Better tape guiding and tape dimensional stability is needed for better tracking performance as track widths are reduced and track densities are increased. Higher track density necessitates the use of narrower data tracks that are placed closer to the tape edge; tape edge damage becomes a concern. During drive operation, damage to the tape edge may result in tape dimensional changes, leading to problems in tracking, generation of loose tape debris, which may show up at the head-tape interface and cause signal loss.;An attempt is made to employ micro/nanotribological techniques to detect wear precursors for the tape head materials. Nano-Kelvin probe is used to detect changes (structural and/or chemical) occurring at the surface top most layers under wear at ultra low loads, which precede appearance of wear debris and/or measurable wear scars. The effect of environmental conditions on the durability of the head-tape interface is studied for a commercial tape drive with a magnetoresistive head and belt driven cartridge loaded with metal particle tape. Possible failure mechanisms are discussed.;An increase in the pole tip recession (a spacing between a head and a tape) results in a signal loss in magnetic tape drives. Test results and analytical modeling suggest that three-body abrasion is the operative wear mode. We study three-body abrasion in detail, by injecting loose particles into the head-tape interface. An experimental setup has been developed. This study of the root cause provides some information about what ultimately needs to be controlled (particle size, concentration, hardness) to minimize pole tip recession.;The research also addresses tape guiding and associated tape edge damage by correlating the occurrence and severity of edge damage with the type of the guides, edge guiding forces, operating conditions and number of file passes. An experimental setup has been developed to measure tape displacement (tape lateral motion) perpendicular to the direction of tape motion and normal forces at the tape edge-flange interface. A methodology has been developed for evaluation of magnetic tape edge quality. The proposed methodology allows quantitative evaluation of the quality of tape edges.