The shock performance of the head/disk interface (HDI) of 3.5 and 2.5 in. hard disk drives (HDDs) is investigated. The displacement of the actuator arm, the suspension, and the disk due to linear shock loads is studied experimentally for both non-operating and operating states of the disk drive. A finite element model of the disk drive was developed to simulate the shock response. Numerical simulation results and experimental results are compared and presented.

Commercially available microdrives were tested using linear and rotary shock and vibration testing equipment. Several microdrives designed with different slider and disk configurations were tested to track hard and soft errors as well as head/disk failures. The shock amplitude for operational and non-operational shock was gradually increased to determine the maximum shock that a microdrive could withstand before failure. After failure, the microdrive was examined to determine whether a mechanical failure occurred or whether the failure was due to a magnetic hard/soft error. During a shock event, the displacement and frequency of the vibrations of the microdrive were examined at various locations on the arm and suspension. A scanning laser Doppler vibrometer (LDV) was also used to determine the amplitude and frequency of the vibrations of the front cover and to investigate whether these vibrations contribute to failure of the head/disk interface. A finite element model of the disk drive was also developed to simulate the shock response. The maximum amplitude for failure to occur was determined numerically for operational and nonoperational conditions using a pulse width of 2 ms. A comparison of experimental and numerical results is given.

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Several air bearing designs were investigated with respect to dynamic Load and Unload (LUL) induced vibrations. Different ABS designs as well as design changes in the suspension of heads were analyzed using an LDV scanning system as well as a Capacitance Probe unit synchronized together. It was observed that the head and suspension exhibited either stable or unstable flying height behavior during the Load or Unload process over a range of velocities to and from the ramp. The results were used to determine a range of LUL speeds that prevented unstable head resonances as well as disk dings and scratches. Most of these head resonances were due to dynamic instabilities of the suspension and head system. The resonance points were investigated at the center and trailing edges (roll and pitch sensitivity) of the head and suspension. A Polytec LDV and Capacitance Probe were used to follow the stable and unstable flying behavior of the head while stationary and the ramp was allowed to move. Methods are discussed to minimize and dampen out the most severe head/suspension vibration levels. Simulation of the flutter of the integrated lead suspension traces due to air flow and possible ways to damp the flow induced resonance is also discussed 1 Introduction