Three dimensional study of air flow in 3.5 inch hard disk drive (HDD)

Abstract

The Hard Disk Drive (HDD) has also improved the development in order to gain more capacity and access time. The higher spindle motor speed is needed. The change of motor speed affects the airflow inside of the HDD. It is well known that airflow is one of the factor of the head recording vibration while the head is flying on the data track. This paper is to study the airflow in the 3.5-inch disk single head with 7200-rpm motor speed. The 3D Finite Element Model will be used in this study to compare the airflow of 2 different Head Gimbal Assembly (HGA) position models, Outside Disk position (OD) and Inside Disk position (ID). The simulation results by RNG K-epsilon found that the change of HGA position has affected the airflow inside of HDD with the velocity of air when it buffets and flow across the arm and HGA at OD is faster than the ID. The causes are due to 1. The constant angular velocity of airflow on the disk, the velocity outside is faster than inside. 2. The airflow from the outside of the disk (Voice coil area) returns in to the disk area then buffets and crosses the arm and HGA at the outside disk position. So, the arm and HGA at OD position will face the vibration problem higher than the ID position. These results will be used for the next study in the flow inducing vibration on the HGA.