Evaluation technique of head/tape contact using acoustic emission

A new on-line methodology has been developed for both evaluation and analysis of head/tape interface phenomena. It uses the direct relationships between the power in the acoustic emission (AE) signal and wear, and between the power in the AE signal and the normal force acting on the magnetic head. The AE transducer is directly mounted onto the head assembly of a VCR mechanism in order to measure the head/tape contact behavior. This technique has been used to: (a) monitor the effect of relative humidity on head wear; (b) investigate the wear characteristics of Mn-Zn ferrite as a function of crystallographic orientation without direct measurement of the wear volume; and (c) evaluate tape abrasiveness. Explicit correlations were also obtained for the normal force acting on the magnetic head, the tape wrap angle around the head, and the reproduced signal flatness in terms of the tape transverse stress distribution. Moreover, the normal force as a function of the tape stress distribution is closely related to the longitudinal tape vibration at the head exit region.