The optimum design of micro gripper for lifetime improvement based on fatigue analysis and six sigma analysis

Abstract

This article reports a problem in hard disk drive manufacturing (HDD) process and a practical solution. A traditional micro gripper of stainless steel 304, practically used in an HDD factory, has a low life expectancy. Therefore, the fatigue analysis was employed to solve this problem. Firstly, 27 cases of possible designs of micro gripper were proposed according to the full factorial design of six sigma (6σ) analysis. Each case is different regarding the micro grippers shapes which are degree, radius, and length. Secondly, 3D models of the micro gripper for all cases were created and transferred to the finite element analysis to simulate the equivalent stress and the compressive force. After the simulation completed, we found that the optimum design of micro gripper has 457.9 MPa of the equivalent stress and 0.991 N of the compressive force, which was less than those of the traditional design. Finally, the optimum design was brought to analyze in more details by using the fatigue analysis. The comparing results of simulation showed that the maximum equivalent stress and the compressive force of the optimum design compared to the traditional design were reduced 14.5% and 19.4%, respectively. These make approximately extending 136.5% of the life cycle and increasing 17.5% of the safety factor. This improvement was expected that it could be able to extend the lifetime of the micro gripper and save up to 60 million dollars annually.