Simulation on contact between the droplet and the slider at head-disk interface based on water-hammer pressure model

Abstract

To understand the cause of read/write error due to lube accumulation, a model to simulate the slider's response to the contact impact, which can occur between a lubricant droplet on the disk and a slider, was developed. The contact impact model is based on the water-hammer pressure model with an additional damping force, where the wave-shock pressure is assumed to function as the contact pressure, and the damping force defines the damping characteristics of the impact which are due to the lubricant's high viscosity and squeeze between the droplet and slider contact area along the slider local velocity direction. The transient contact impact is dependent on lube droplet density, disk velocity, pitch angle of the slider, and contact area between the droplet and the slider. The measured read/write signal jump due to lube pickup can be explained by the simulation results. This modeling and simulation are helpful to us in understanding the read/write signal loss due to a lube droplet at head disk interface.

Characterization of light contact in head disk interface with dynamic flying height control

“…3. The light contact or lubricant surfing has been widely discussed (Vakis et al 2009;Ng et al 2009;Canchi and Bogy 2010;Li et al 2010). In order to extract information from the weak signal in the region III in Fig.…”

“…Juang and Bogy (2007) investigated the relationship between air bearing surface design and thermal actuation of a slider. More recently work can be found in (Xu et al 2009;Hua et al 2009;Vakis et al 2009;Shiramatsu et al 2009;Li et al 2009;Tani et al 2009;Ng et al 2009;Canchi and Bogy 2010;Knigge et al (2006); Li et al 2010;Canchi and Bogy 2010). Although the above studies have clarified many aspects of current-induced thermal pole tip protrusion, there are still many areas lacking of understanding.…”

Air Bearing Design to Prevent Reverse Flow from the Trailing Edge of the Slider

“…The accumulated lubricant on the slider surface may transfer onto the disk surface to form a droplet there. And, the slider and the lubricant droplet might make contact, which might induce a small vibration of the slider, causing a signal jump in a hard disk drive [7,8]. Figure 3 shows the air flow pattern at 0.9 h, reverse flow and stagnation line on the whole ABS at the disk inner diameter (ID), middle diameter (MD) and outer diameter (OD).…”

“…This is because the lubricant layer not only consumes valuable head/disk spacing and modifies the effective ABS profiles, but also because it may impose other negative effects such as flying stiction on the slider's flying dynamic performance. Recent research has indicated that the contact between the lubricant on the disk and the slider could cause the slider to vibrate, which would result in the read/disk signal loss that is usually observed in hard disk drive failure [7,8].…”

Flying Instability due to Organic Compounds in Hard Disk Drive

“…At this small clearance flying instability, which results in a few nanometers of clearance variation, may cause read/write errors due to the high sensitivity of magnetic recording performance to clearance. In addition to direct contact between head and disk, collision between a lubricant droplet and head may cause vibrations and induce a read/write "signal jump" such as reported by Li et al [1]. Fowler and Geiss [2] observed droplets of OC (alkane) on the head that can cause the stiction at the HDI with a visualization setup.…”