A study of geometrical a changes in a head surface caused by sliding wear against a tape. (1st Report, Experimental study).

Abstract

The changes in head geometry caused by head-and-tape contact are investigated experimentally and analytically. Dummy heads made of copper and lapping tapes are used for wear tests in which the dummy head slides on the lapping tape travelling under constant tape tension and sliding velocities, leading to a constant contact force. An optical interference microscope and a surface profilometer are used to examined the head geometries, and an optical microscope is used to examine the head-and-tape contact area. The tape deformation is calculated using the finite element method under a condition of uniform pressure applied to the tape. From these investigations, the following is clarified. At the early stage of wear, the head wears selectively where the contact force is high. The head reaches specific geometries in spite of the difference in initial geometries of heads. This means that the contact pressure between the head and tape becomes uniform in accordance with the progress of wear. The head geometry in a steady state of wear is very close to the tape deformation calculated under uniform pressure. This result shows the occurrence of uniform wear, and the wear volume V calculated by V = cPvt, where c is the specific wear rate, P is the contact force, ν is the sliding velocity and t is the sliding period.