Enhancing tribological performance of the magnetic tape/guide interface by laser surface texturing

Air-lubricated foil bearings are used in a variety of applications such as turbomachinery, journal bearings, dentistry equipment, etc. [1–3]. One of the most intricate applications of air-lubricated foil bearings can be found in magnetic tape drives [4], where a magnetic tape moves over a read/write head and tape drive components such as guides (stationary) and rollers (rotating). Friction is an important parameter in designing a tape transport for a commercial high-performance tape drive. The overall friction force between tape and tape drive components determines the torque needed by the motor to drive the tape and affects the wear of the tape. Metal particulate (MP) tape is widely used in commercial tape recording systems since the tribological performance of the magnetically superior metal evaporated (ME) tape is inferior to that of MP tape. Lateral tape motion (LTM) is defined as the timedependent motion of the tape perpendicular to the tape transport direction. It is a friction related phenomenon that can cause track misregistration [5]. Although friction between tape and tape drive components was observed to attenuate LTM [6–8], it is well known that tape drives with pressurized air bearing guides instead of rotating guides exhibit significantly lower LTM than tape drives with rotating guides [9]. Elimination of rotating tape drive components suppresses LTM due to run-out of those components. However, pressurized air bearing guides require an external compressor, which is an obstacle for commercialization of this type of tape drive. Based on the above information, it is therefore desirable to create an efficient self-acting foil bearing between the tape and the guide, thereby eliminating the need for an external compressor, while still benefiting from a low friction air bearing. In a recent study [10], it was observed that for a tape tension of 1 N, a tape speed of at least 8 m/s was needed to achieve full fluid lubrication and hence, a low friction coefficient. This paper explores the possibility of creating an efficient low speed air bearing between a magnetic tape and a cylindrical guide, thereby expanding the speed range of low friction. We use a novel approach to tape guide design by using laser surface texturing (LST) of the guide surface. We have compared the tribological performance of the laser surface textured guide with various non-textured guides, thereby showing the benefits of textured guide surfaces.