Study on static characteristics of air bearing films over bit pattern media in hard disk drives

A method that combines the finite element method and Newton-Raphson iterative method is applied to study the effects of bit pattern media (BPM) on the static characteristics of slider in the hard disk drive. The static characteristics of sliders with different structures and geometry dimensions of BPM such as pitch angle, roll angle, air bearing film thickness, pressure and load capacity are calculated. The numerical results show that the bit shape and its dimension parameters have significant effects on the static performances of the slider. Compared with the smooth disk, when the slider is flying over the bit pattern media, the pressure distribution in the central region which is close to its read/write head shows a discretization feature. The gas-film load capacity and minimum film thickness of the slider gradually decrease as the bit height increases, while the changes of other characteristics are closely related with the bit distribution. Moreover, a comparison with a cylindrical bit pattern media shows that the smaller roll angle may produce lager maximum film pressure, load capacity and minimum film thickness, and that the static characteristics of the slider flying over cuboidal bit pattern media are better than those over cylindrical bit pattern media. These results are of great significance for the design of structure and geometry parameters of bit pattern media. © 2016, Editorial Office of Journal of Xi'an Jiaotong University. All right reserved.