Theoretical Prediction of Ramp Loading/Unloading Process in Hard Disk Drives

Air bearing slider dynamic performance during the ramp loading and unloading processes was investigated theoretically in this paper. The air bearing was modeled by the modified compressible Reynolds equation, and it was solved by the finite volume method. Slider dynamic equations were derived in this paper to include the ramp loading/unloading mechanism. These two sets of coupled equations were solved iteratively. Both Tripad and negative pressure air bearing (NPAB) were included in the analysis. Effects of loading/unloading velocity, disk rotational speed, as well as suspension flexure stiffness, were investigated. Slider-disk impact will occur during the Tripad loading process, especially at high loading velocity. On the other hand, this impact can be avoided for an NPAB at loading velocity up to 200 mm/s. However, an NPAB requires a longer unloading time due to its suction force. This unloading process is further delayed if a soft flexure is combined with an NPAB.

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