Analysis and design of hydrodynamic journal air bearings for high performance HDD spindle

Abstract

In this paper, we proposed the design concept of NRRO-free non-contact bearings for a high performance hard disk drive (HDD) spindle. We numerically analyzed three types of hydrodynamic journal air bearings [gas dynamic bearing (GDB)], such as a partial herringbone groove, a sinusoidal wave, and a taper-flat type. And we compared their performances in terms of pressure distribution, load capacity, radial stiffness, unbalance response, and stability threshold. For the design examples, we examined the Case 1 with 2.0 μm bearing clearance and 10000 rpm, and the Case 2 with 1.0 μm clearance and 15000 rpm. As a result of numerical analysis, we found that the taper-flat type was the most promising for high performance HDD spindle compared with the other types. It can have the bearing stiffness of about 3.0 × 10⁶ N/m in Case 1 and of about 2.0 × 10⁷ N/m in Case 2. We also discussed the allowance of parameters for the optimal design of the taper-flat type journal bearing.