Ultrasonic Applied in Super Precision polishing of Magnetic Recording Heads

In the traditionary nanogrinding way, a sub-nanometer smooth surface can be achieved, but the PTR can be only controlled under ten nanometers. To find a new way to reduce the PTR. ultrasonic was applied in the polishing experiment. At first, the experiment with two kinds of samples. AlTiC bulk and NiFe bulk were carried out in free abrasive lapping way with the float-piece polisher. It was discovered that the material removal rate and the roughness of surface is improved in different extent of different material, the material removal rate (MRR) of the AlTiC bulk was increased from 10 nm/m to 16 nm/m. while the MRR of the NiFe bulk was increased from 23 nm/m to 30 nm/m. Encouraged by the result of the experiment, the specimen of 70 mm*1.25 mm rowbar with 60 GMR magnetic head was polished in the same condition, as a result, the PTR was reduced from 65 nm to 45 nm. Furthermore, the ultrasonic was introduced into nanogrinding of recording head. In this way. the PTR was controlled at lnm or so and smoother surface was achieved. Two kinds of mechanism about the role of the ultrasonic were prompt to explain in what way that the material removal rate is improved and why the improved ratio is different in different materials in the polishing.