Numerical and experimental investigations of the head/disk interface

Experimental techniques were developed for the investigation of slider dynamics for ultra-low spacing head/disk interfaces. Voltage pulsing and mapping techniques were established for the investigation of clearance and flying height modulation as functions of head/disk interface parameters. Numerical methods were developed to analyze forces acting on sliders of discrete track recording head/disk interfaces. A finite-element- based air bearing simulator was used to predict the steady state flying characteristics of arbitrarily shaped slider contours flying over discrete track recording disks. The direct simulation Monte Carlo method was used to simulate the rarefied gas flow in nano-channel

Numerical and experimental investigations of the head/disk interface

Experimental techniques were developed for the investigation of slider dynamics for ultra-low spacing head/disk interfaces. Voltage pulsing and mapping techniques were established for the investigation of clearance and flying height modulation as functions of head/disk interface parameters. Numerical methods were developed to analyze forces acting on sliders of discrete track recording head/disk interfaces. A finite-element- based air bearing simulator was used to predict the steady state flying characteristics of arbitrarily shaped slider contours flying over discrete track recording disks. The direct simulation Monte Carlo method was used to simulate the rarefied gas flow in nano-channel

Numerical Simulation of the Head/Disk Interface for Patterned Media

The use of patterned media is a new approach proposed to extend the recording densities of hard disk drives beyond 1 Tb/in.2. Bit-patterned media (BPM) overcome the thermal stability problems of conventional media by using single-domain islands for each bit of recorded information, thereby eliminating the magnetic transition noise (Albrecht et al., Magnetic Recording on Patterned Media, 2003). Considering steady state conditions, we have transferred the pattern from the disk surface onto the slider surface and have investigated the pressure generation due to the bit pattern. To reduce the numerical complexity, we have generated the bit pattern only in the areas of the slider near the trailing edge, where the spacing is small. Cylindrical protrusions were modeled using very small mesh size on the order of nanometers to obtain the flying characteristics for the entire slider air bearing surface (ABS) using the “CMRR” finite element Reynolds equation simulator (Duwensee et al., Microsyst Technol, 2006; Wahl et al., STLE Tribol Trans, 39(1), 1996). The effect of pattern height, pattern diameter, slider skew angle, and slider pitch angle on flying height of a typical slider is investigated. Numerical results show that the flying height decreases for a patterned slider and the change in flying height is a function of the pattern height and ratio of the pattern diameter to the pattern pitch. In comparison to discrete track media, the flying height loss is larger for a patterned slider disk interface for the same recessed area of pattern

Tribological testing of sliders on discrete track media and verification with numerical predictions

“Flyability” tests were conducted with sliders designed for discrete track recording disks. Laser Doppler vibrometry and acoustic emission were used to characterize the dynamics of the sliders as a function of discrete track parameters. Lubricant depletion was observed depending on the slider nominal flying height. Comparison of experimental results with numerical predictions showed good qualitative agreement