Simulation of Airflow inside a Computer Hard Disk Drive to Develop an Impinging Air Jet Particle Detachment System for Cleaning Head Stack Assemblies

A computer hard disc drive (HDD) contains a number of mechanical components inside. One of these is the head stack assembly (HSA). This paper describes how numerical simulation was used to investigate the particle velocities and trajectories that are experienced by the HSA inside an HDD. The resulting velocity and particle trajectory information can then be used to understand the key design variables to be used to invent an effective system that cleans particles from the HSA surface prior to installation inside the drive. The HDD performance is highly sensitive to such particles. The resulting cleaning system uses impinging air jets to remove solid particulate contaminants adhering to the surfaces of the HSA. This air jet system was then evaluated using experimentation to validate that the quantity of particles, ranging in size from 0.2 to 5 μm in diameter, was effectively reduced after implementation of the new system.