Friction in Magnetic Tapes II: Role of Physical Properties

Abstract

Experiments were conducted to examine the relationship between the coefJicient of friction and the physical properties of magnetictape surfaces. Based on the experimental data, it was obserued that the coefficient of friction has a strong dependence on complex modulus rlf the materials i n contact. Sofiening of the polymer binder of the tape surface at elevated temperatures results i n a n increase i n friction. This demonstrates the need for a relatively hard binder with tz softening temperature (at the appropriate rate of deformation) above the maxzmum operating condition. Surface topography has a strong influence on friction. A rougher surface results i n higher contact stress at the contacting asperities, and, therefore, in less nu1 contact area and lower friction. A rougher surfnce, however, may result i n higher head wear and poorer magnetic signal amplitude. These observations demonstrate the need for optimization of the surface topography to maintain high performance of a magnetic-&ape product.

Measurement of Creep Properties in Compression and Their Influence on the Friction of Magnetic Tapes

“…Although PET film of 0.025 mm (92 gauge) as a substrate and ink thicknesses of about 3 to 5 pm are used in most magnetic tapes, we selected thicker films. Meaningful data on thinner PET films or magnetic tapes cannot be obtained because (1) the ratio F (to be discussed later) should be kept to a minimum, (2) it is difficult to hold the thinner films flat, and (3) the deflection of thinner films is too small to measure.…”

“…[ l ] and [2], we get Therefore, to keep the ratio F to a minimum for a given specimen material and thickness, the radius'of the probe should be as small as possible. Commercially available probes come in radii of 0.457, 0.889, and 1.524 mm; we chose the 0.457 mm probe for this study.…”

“…Interlayer pressure at EOT near the hub was about 1.5 MPa. Friction measurements were made before and after aging using a reciprocating friction tester (2). In this tester, a tape segment was pulled over a glass head at a speed of 1.5 cmls.…”

Frictional Properties as a Function of Physical and Chemical Changes in Magnetic Tapes During Wear

“…vacuum columns), capstans, supply and take-up reels, and cleaner blades. The normal pressure in a tape drive is usually low (7)(8)(9)(10)(11)(12)(13)(14) and the number of full-file passes a tape is subjected to during its lifetime is from 200 to 5000 passes.…”

“…A reciprocating friction test (ReFT) apparatus was used to measure the coefficient of friction (11). During the test, a tape is pulled back and forth over a glass head (one cycle) at an average sliding speed of about 1.5 cmls.…”