Types Of Sliders Research Articles

The effect of slider on lubricant loss and redistribution

The effect of the slider geometry and ABS on lubricant loss and redistribution has been studied by flying heads over disks with step-profile lubricant film. Two types of sliders, one with a negative pressure air bearing and truncated side-rails and the other with a positive air bearing, in the standard catamaran geometry, were used. The disks after flying were examined with a scanning reflectance analysis probe. After a short period of time, it was found that both sliders caused a comparable amount of lubricant depletion in the thick-film region. However, the redeposition in the thin-film region is seen prominently only under the slider with the negative pressure air-bearing. The result suggests that the lubricant depletion in one case results primarily from net lubricant loss or pickup, and in the other case from transfer and redeposition. Based on these results, a transfer mechanism under each slider type has been proposed. A discussion on the design implications is also included.

102 ヘッドスライダのディスク表面うねりに対する追従特性と最適設計指針

This paper describes optimum air-bearing design of a tri-pad slider in terms of tracking ability to micro-waviness based on theoretical analysis of the two-degree-of-freedom slider model and the distributed and concentrated air-bearing stiffness model. Although a short tri-pad type slider was introduced through the load/unload technique, we point out that this type of slider is superior to the traditional rail type slider in terms of tracking ability to micro-waviness. More importantly, the distance between head-gap position and the rear air-bearing center should be made as small as possible. The spacing variation due to lower mode resonance can be eliminated if the positions of front and rear air-bearing centers are located at the center of percussion. The resonance amplitude of the higher order mode in spacing variation can be reduced if the length of the rear air-bearing pad is designed to be 1.2∼1.3 times the wavelength of the higher mode resonance frequency. Since the momental stiffness of the front air-bearing prevents the head-gap from tracking micro-waviness, the front air-bearing length should be made short or the ratio of rear to front air-bearing stiffness should be made large. If the resonance amplitude of the lower mode must be decreased, the front air-bearing length should be designed to be 1.2∼1.3 times the wavelength of the lower mode resonance frequency.

The effects of slider design on thermal asperity rejection capability

Particle contamination has been an ongoing problem affecting the reliability of the magnetic hard disk drives. Especially the recent use of MR head requires much tighter control of particle contamination due to thermal asperity (TA) phenomenon. In this study, the effects of slider air bearing surface design on TA reduction capability were investigated by manufacturing two types of sliders. Numerical methods were used to simulate the motion of particles in the head/media interface. Experiments were conducted to verify the results predicted by the numerical simulation. Drives were built and exposed to particle contamination using a particle injection chamber, which turned out to be a very simple and reliable particle generation method over conventional aerosol technique. Then the number of TA generated in the drives was recorded and compared. Also the contacts between slider and particles were investigated by acoustic emission study. It was found that a new ABS design, which has aerodynamic U-shaped rail and central flow passage, was beneficial in reducing the particle contamination on the slider.

Effect of particulate concentration, materials and size on the friction and wear of a negative-pressure picoslider flying on a laser-textured disk

The effect of particulate contamination on friction and wear between a negative-pressure picoslider and a laser-textured disk has been studied. Particles of different concentration, materials and size were injected at the head-disk interface consisting of disks with various textures and slider types at different speeds. Durability increases and coefficient of friction decreases as the disk speed is increased in a contaminated environment. Frictional characteristics and durability in the data zone were better than those in the laser-textured zone. It was also found that durability of head-disk interface (HDI) decreased as the particle concentration increased. Hard particles and large particles made the HDI failure early and resulted in an extensive damage to the slider and disk surfaces. The interface durability with the picoslider was better than that with the nanoslider at any condition in a contaminated environment. Based on the test results, the mechanisms are proposed to explain the reasons why durability with the picoslider is superior to that with the nanoslider and the mechanism of the HDI failure with the picoslider is also presented.

Automated process planning for the manufacture of sliders

This paper presents a methodology of a computer-aided process planning system for an injection mould component, slider, which will facilitate the standardisation of process planning and significantly reduce lead-time. A combination of generative and variant approach is used for the development of the system. The input to the system is a 3D slider model. Firstly, the system classifies the slider types and extracts the feature parameters from the model. Each slider type refers to a standard process plan template, in which a set of processes in sequence is presented. Secondly, the system selects machines, cutters, fixtures and cutting parameters for each process in the plan template based on the actual dimensions of features and the available machining resources. The process plan execution is then simulated on the screen step by step. Although the system is developed for sliders, the approach is generic in nature and could be easily extended to include other mould components, such as lifters, mouldbases, etc.

A pneumatic air table realized by micro-EDM

This paper presents a one-dimensional (1-D) pneumatic actuator fabricated by combining several micromachining technologies such as microelectrodischarge machining (micro-EDM) as well as isotropic and anisotropic wet etching. Unlike the existing pneumatic actuators, which usually convey the object by means of friction, this device employs the dynamic pressure of inclined driving jets in order to enhance the horizontal transportation performance. Typical slider speeds of up to 5 cm/s can be obtained. Comparisons between different types of sliders are presented. By an appropriate patterning of the slider bottom surface, the speed could be increased by 50%-60%. Similarly, a maximum tangential force of 20 /spl mu/N (equivalent shear stress: 2.2 /spl mu/N/mm/sup 2/) was obtained using this dynamic pressure concept. The latter is about two times larger than that of a slider with a smooth surface.

1/f noise and its coherence as a diagnostic tool for quality assessment of potentiometers

The excess noise of different types of potentiometers has been investigated, and all showed a 1/f noise power-spectral density. Two types of conductive tracks are considered: carbon black resin type and metal-oxide glass cermet type. Also considered are different types of sliders: 1) metal-point contacts, 2) metal-line contacts and multiple-finger contacts, and 3) carbon brush contacts. The contributions of the end contacts, the stationary wiper (movable) contact, and the track have been investigated. The resistance and the noise of the stationary wiper contact are constriction dominated. Two different biasing conditions are proposed to measure either the coherence between current fluctuations or between voltage fluctuations in a potentiometer. The coherence measurement can serve as a fast diagnostic tool for the noise characterization and the quality of the movable contact in a potentiometer. Physical models are proposed to explain experimentally observed trends. Potentiometer 1/f noise is due to contact noise between grains in the track. >

A computational analysis for thin air film lubrication of magnetic recording disk memory. (1st Report).

The rarefied gas lubrication was analyzed based on modefied Reynolds equation and a FEM formulation was adopted for the computation with a trial function separated locally. The air film under the slider has such a thin dimension as 1/3000 (depth/width) and flows in one direction. Therefore the distribution of the pressure in transversal direction is almost constant except the boundary region. Typical two dimensional FEM formulation is not adequate for this type of problem. Results presented in this report show the above perspective. The computational analysis was done for three types of sliders, that is, a tapered flat slider, a two rail slider and a zero load slider. All results reveal the applicability of the present method of computation.

Analytical Stability Criteria for Gas-Lubricated Sliders for Magnetic Disk Drive

Stability criteria for gas-lubricated sliders for magnetic disk drives are analyzed using Hori's method. Some relations between flotational stability and float factors are discussed. Equations of slider motion for a rigid body slider are expressed using linearized coefficients for gas-lubricated films accounting for second-order slip flow. Stability of the slider is analyzed using the Routh-Hurwitz stability criteria. The calculated results make it clear that some types of sliders become unstable when ambient pressure is reduced, or gas compressibility number is increased. Furthermore, analytical results were confirmed not to conflict with experimental work. Presented as a Society of Tribologists and Lubrication Engineers Paper at the ASME/STLE Tribology Conference in Baltimore, Maryland, October 16–19, 1988

Dynamics of magnetic recording sliders investigated using laser Doppler interferometry

The dynamic response of low flying sliders is investigated using a laser Doppler vibrometer. The motion of sliders excited by an artificial defect is studied in both the time and frequency domain and the dynamic response of different types of sliders is examined, including narrow rail, ‘bleed-slot’, and negative pressure sliders. In addition, suspension loading and disk velocity effects on the slider dynamics are investigated. A simple spring/mass model describing the dynamics of the slider is discussed.

Measurement of head/disk spacing modulation using a two channel fiber optic laser Doppler vibrometer

A two-channel laser Doppler vibrometer system is described for studying spacing modulation of the head/disk interface in a magnetic recording disk file. Three types of sliders, namely a standard two-rail slider, an experimental negative-pressure slider, and a cross-cut slider, are studied. In comparing the results from the single-channel and dual-channel laser Doppler systems, excellent agreement is observed for the resonant frequencies of the air bearing. The single-channel system, however, exhibits problems with offset in the velocity and displacement signals that are absent with the two-channel system. >

An investigation of wear and material transfer in magnetic recording disk files

Wear of specially designed and fabricated slider bearings, similar to the ones used in magnetic recording disk files, is investigated as a function of sliding velocity using interferometric analysis for measuring dimensional changes due to wear. The relationship between wear and the amount of material transfer is determined, after neutron activation, utilizing autoradiographic methods and optical microdensitometer analysis. For the specific slider type investigated, transfer and wear rates are seen to decrease to zero for velocities above 2000 cm/s, thus indicating hydrodynamic flying of the slider.

自動スライド式メリヤス針

自動スライド式メリヤス針