Narrow Results

As the areal recording density increases in hard disk drives (HDDs), the flying physical spacing between the head and the disk decreases and the likelihood of head-disk contact during full speed rotation increases. Therefore, the simulation and modeling of the air bearing slider with ultra-low flying heights becomes an important issue for the operational shock simulation. The static/dynamic properties, including the influence of the radial position and the skew angle of the slider, the rotating speed of the disk, and the shock simulation, of the air bearing slider were analyzed. Generally speaking, for a given rotating speed of the disk, as the slider moves from the inner diameter to the outer diameter, the maximum contact pressure, the skew angle, the pitch angle, and the maximum air bearing pressure increase; while the flying height decreases. These trends are strengthened by a faster rotating speed of the disk. There are obvious oscillations in the air bearing force and the minimum spacing when contact occurs during a shock.

This paper presents some results of simulation using ANSYS CFX software in design air spindle which has the structure in the form of orifice and grooves to ensure uniform pressure distribution and avoiding air hammer; it is also easy to manufacture and reduces costs. The results of simulation are good in investigating operation of air-spindle which is changed some parameters to find the optimal working mode for the air spindle with speed in the range of 5000–20,000 rpm.

An efficient scheme was developed to analyze head-disk interfaces (HDIs) in hard disk drives. HDIs were studied by decoupling the nanometer scale variations of the air bearings and the micrometer scale changes of the suspensions. The nonlinear variations of the air bearing forces and moments were described with analytical expressions obtained from a surface fitting scheme. Combined with a 3 degree of freedom (DOF) suspension model whose parameters were estimated from a comprehensive finite element model, the historical behaviors of a subambient slider during an unloading process can be obtained in a very short computation period, thus providing a way of exploring a large number of parameter values of the suspension stiffness matrix.

A 1 N•m torque standard machine has been designed and developed at National Institute of Metrology (NIM) since 2011. The torque standard machine adopts the moment arm-deadweight type, the air bearing with low friction is adopted to support the moment-arm at the fulcrum, the invar with the low expansion coefficient is used as the material of the moment-arm, the weight suspension part and weight loading system are specially designed to ensure the applied force by small weights accurately and reliably. This paper introduces the mechanical structures of the machine, the electrical control system is described. 1 N•m torque standard machine is capable of realizing the torque from 1 mN•m to 1 N•m both in clockwise and anti-clockwise directions.