Load adjusting machine for magnetic disk drive head gimbal assemblies

摘要

A computer controlled regram machine for adjusting the loads on head gimbal assemblies to bring the loads within a desired specification window defined by upper and lower window specifications. The regram machine includes a load cell for measuring actual gimbal assembly loads, a mechanical bending mechanism for implementing mechanical adjust procedures to increase and decrease the gimbal assembly loads, and a heat source for implementing light adjust procedures to decrease the gimbal assembly loads. The algorithm executed by the machine includes: (a) initiating mechanical adjust procedures in an attempt to increase the gimbal assembly loads to a bend load target if the measured loads are below the specification window, the bend load target being a load greater than the upper window specification and an optimum load from which to initiate light adjust procedures; (b) initiating mechanical adjust procedures in an attempt to decrease the gimbal assembly loads to the bend load target if the measured loads are greater than a light adjust threshold, the light adjust threshold being a load greater than the bend load target and characterizing the upper limit of load changes that are to be implemented by light adjust procedures; (c) initiating light adjust procedures in an attempt to decrease the gimbal assembly loads to the specification window if the measured loads are above the specification window but less than or equal to the light adjust threshold; and (d) repeating steps (a)-(c) until the measured loads of the gimbal assemblies are within the specification window.