Lapping control of Hard Disk Drive Heads (I): Modeling

Bar lapping is a key process in fabricating computer hard disk drive heads. The purpose is to remove a small amount of material in a way that minimizes the stripe height variation across the bar. This article presents the first part of this study: establishing a method of simulating the material removal process. The Preston model is identified to be a reasonable constitutive relationship relating lapping rate to pressure and relative velocity. A pressure estimation method is established based on the modified beam on elastic foundation model (MBOEF) to incorporate the effect of surface shape. Simulation is conducted based on the proposed constitutive relationship and MBOEF. Results show good agreement with production observations. Hence the simulation model can serve as a tool to identify the structure of the lapping control model in the second part of this study.