Air Bearing Force Measurement of Pico Negative Pressure Sliders During Dynamic Unload

Abstract

The air bearing forces of “pico negative pressure” (1.25 × 1.0 mm subambient pressure) sliders during the unload process were investigated experimentally. A high speed vertical load/unload mechanism with a sensitive force transducer was developed to measure the air bearing forces. Force histories were measured at various disk rpm and unload velocities. The force histories showed that the suspension load dimple separated from the load beam during the lifting. This separation was held to an acceptable amount by flexure limitors built into the suspension. Force-displacement curves show the need for control of the gap between the limitor and load beam. A technique was developed to determine critical suspension parameters for use in the CML Dynamic Load/Unload Simulator. Simulation of the force history was then in excellent agreement with experimental results. Both simulation and experimental results showed that the lift-off force decreases with increasing disk rpm. Experimental results also showed that higher unload speeds lead to larger lift-off forces. By selecting the correct disk rpm and unload speed, the lift-off force could be minimized. [S0742-4787(00)00103-X]