Exploring the Effect of Stick-Slip Friction Transition Across Tape-Roller Interface on the Transmission of Lateral Vibration

In magnetic tape drives, lateral in-plane vibration of the tape leads to misalignment between data tracks and read/write head's position resulting in reduced storage capacity. To attenuate this lateral tape motion (LTM), surface guides-which include grooved, porous or roughened rollers-are used. The axial motion of the tape over the roller surface switches between two states: a sticking state when the axial force is smaller than the static frictional force; and a slipping state when the axial force is larger than the frictional force. A good understanding of the physical phenomena involved in this frictional interaction between the magnetic tape and surface friction guides will allow the appropriate and optimal choice of roller characteristics. We conduct a parametric study of frictional interaction between roller surface and the traveling magnetic tape by systematically varying the axial tension and transport velocity of the tape. An experimental setup is used to independently control these parameters and obtain lateral vibration measurements at two equidistant points-upstream and downstream-from the tape-roller interface. Techniques from spectral analysis are applied to the two signals to analyze and isolate the effect of stick-slip friction on LTM. It is noticed that the coherence function between the LTM signals provides valuable insight into the nature of stick-slip friction at the interface. We subsequently use it as a metric to construct and understand the “dynamic phase diagram,” i.e., to demarcate regions in the tension-velocity phase-space where predominance of stick or slip occurs.