Ultra Precision Polishing of GMR Hard-Disk Magnetic Head

Though the material of substrate of magnetic head is very brittle, it can be removed in ductile way by controlling load and size of diamond in lapping. Different material removal mechanism can be produced by rolling grain and sliding grain. The material is removed in fatigue way by rolling grain but removed in micro-cutting way by sliding grain. For very brittle and hard reason, the substrate can be removed in fatigue way, while the pole tip can be removed by micro-cutting for the ductile reason. In theory, the pole tip is easy recessed when the grain mainly moved in sliding way. In this investigation, the ratio of rolling grains to sliding grains was adjusted by changing the pad roughness, diamond size, size distributing and lapping load to obtain an excellent magnetic head surface and high removal rate. The quality of magnetic head surface after nano-grinding will be better than that after lapping, but the removal rate in nano-grinding will be lower than that in lapping. So, nano-grinding was only used in the final process. The fabricating of nano-grinding pad is the main factor that influences the surface quality. Ultra-smooth magnetic head surface was achieved by integrated a serial of lapping and nano-grinding process