Jin-Gyoo Yoo

Ramp Tolerance Analysis Considering Geometric Errors

Load/Unload (L/UL) system has many components such as ramp, limiter, lift-tab and so on. In this paper, we focus on ramp and ramp tolerance analysis considering geometric errors such as assembling and manufacturing errors because the large ramp geometric errors bring about unloading fail that means unloading process does not occur. Specially, we numerically investigated the effects of ramp tolerance because a ramp has both upper and lower sides. From the analytic method, unloading point, air-bearing breaking point, maximum ramp translation length (TL) and maximum tilt angle (TA) were investigated. Also, we proposed the maximum ramp tolerances such as translation and rotation.

Design and Performance Test of Comb-Shaped Clamp/Spacer for Improvement of Recirculation Filter Efficacy in a Hard Disk Drive

With the recent increase of the rotational speed of hard disk drives, nanoparticle contamination can cause serious problems including thermal asperity. We designed a comb-shaped clamp and spacer to improve the efficacy of the recirculation filter in the operation of the hard disk drive (HDD). We calculated flow characteristics by a commercial computational fluid dynamics (CFD) code for six cases of the comb-shaped clamp and spacer. The calculation results showed that the outward velocity was the highest when the comb-shape angle was 45deg. We measured temporal variations of particle concentration during the operation of the HDD by experiments. Considering the decay rate and the percent clean-up of particle concentration, we found the case of 45deg to be the best design.

Experimental and numerical studies about the effect of airflow on slider vibration with and without a disk damper

As the recording density and data transfer rate of a hard disk drive increase, TPI and rotational speed have been increased so that a single actuator alone may not be enough to control TMR budget. High-speed rotation of a disk induces airflow inside HDD cavity and the influence of airflow on HSA has become critical as TPI increases. A disk damper, which is designed to suppress the disk flutter, changes the airflow significantly so that the E-block and slider are open to the flow with relatively large pressure fluctuation. The effect of disk damper shape on the airflow field is studied numerically and experimentally from the aerodynamic point of view. Unsteady airflow in HDD cavity is simulated numerically by using a large eddy simulation method and frequency spectrum of the pressure fluctuation near the slider is obtained. Numerical results are compared with experimental results for three different-shape disk dampers and two types of E-blocks. The relationship is analyzed between the vibration of the slider and the pressure fluctuation of the airflow near the slider. A newly proposed shape of disk damper shows good characteristics on suppressing the vibration of the slider due to the airflow.

Optimal Design of Slider Air-Bearing for Discrete Track Recording Technology

This paper suggests a design methodology for slider air bearings over a discrete track recording (DTR) disk using a simplified static analysis including the flying-height (FH) loss equation instead of a computationally expensive, time consuming transient dynamic analysis. Because a slider over a DTR disk has different flying characteristics than a slider over a continuous track recording (CTR) disk, the design of the slider requires modification. However, it is challenging to dynamically simulate slider air bearings over a DTR disk. Furthermore, it is nearly impossible to design the slider using an expensive dynamic analysis as a solver. Therefore, we define the flying characteristics of the DTR slider as a function of that of the CTR slider by using the FH loss equation based on averaged flow effect. A design optimization problem is formulated to meet the design requirements of the DTR slider, which include target FH, FH flatness, altitude FH drop, pitch and roll angle ranges, and altitude pitch drop. The design problem is changed to an inverse problem using a conventional static analysis for a CTR disk instead of an expensive dynamic analysis for a DTR disk. Simulation results showed that the optimally designed DTR slider can meet the target FH while satisfying all design requirements over the entire recording band.