Numerical Analysis of Microwaviness-Excited Vibrations of a Flying Head Slider at Touchdown

As an extension of the study presented in ISPS 2016, vibration characteristics of a commercially used head slider in hard disk drives at touchdown are analyzed by using a single degree-of-freedom (DOF) slider model, improved asperity adhesion force model, and air-bearing force model. Using parameter values at the head/disk interface, the total interfacial force was evaluated for various air bearing stiffness ratios r. Microwaviness (MW)-excited slider vibration was simulated near the boundary of instability onset (r = 2.4), and slight instability conditions at r = 2. It was found that the simulated results at r = 2.4 and 2 agree well with the touchdown vibrations of actual slider at ID and MD, respectively. The possibility of surfing recording is discussed.

Effect of Laser Heating on Nanoscale Wear of DLC Thin Films in an Air Environment

To achieve magnetic recording densities greater than 10 Tb/in2, the head-disk interface (HDI) spacing is required to be less than 2–3 nm. Thus far, various technologies, such as heat assisted magnetic recording (HAMR), have been studied and developed to achieve such high magnetic recording densities [1]. To ensure the practical applicability of HAMR, it is important to understand the reliability of perfluoropolyether (PFPE) boundary lubricant films and carbon overcoat or diamond-like carbon (DLC) thin films used on the head slider and disk surfaces under heating conditions [2].

Analysis of Microwaviness-Excited Vibrations of a Flying Head Slider in Proximity and Asperity Contact Regimes

The vibration characteristics of a thermal fly-height control (TFC) head slider in the proximity and asperity contact regimes attract much attention, because the head–disk spacing (HDS) must be less than 1 nm in order to increase the recording density in hard disk drives. This paper presents a numerical analysis of the microwaviness (MW)-excited vibrations in the flying head slider during the touchdown (TD) process. We first formulate the total force applied to the TFC head slider as a function of the HDS, based on rough-surface adhesion contact models and an air-bearing force model. Then, the MW-excited vibrations of a single-degree-of-freedom (DOF) slider model at TD are simulated by the Runge–Kutta method. It is found that, when the MW amplitude is less than the spacing range of static instability in the total force, the slider jumps to a contact state from a near-contact or mobile-lubricant-contact state. It then jumps to a flying state even when the head surface is protruded further by increasing the TFC power. When the MW amplitude is relatively large, a drastically large spacing variation that contains a wide range of frequency components below 100 kHz appears in the static unstable region. These calculated results can clarify the mechanisms behind a few peculiar experimental phenomena reported in the past.