pressure. Contact pressure depends on the head contour,
contact area, head protrusion, tape tension and tape stiffness.
One might surmise that such a study would be possible by
increasing or decreasing one or more of these factors, for
example, tape tension for either system. However, the
complex design of systems and heads makes this approach
not feasible. The issue in complicated slightly by the fact
that LTO heads are slotted and the slots will tend to act as a
reservoir for loose debris, however, we believe that this is a
second order effect. Generally wear rate is inversely
dependent on the material hardness [9] and dependant on
contact pressure [10]. Linear dependencies are only true,
however, if the wear is wholly abrasive. In this case, wear
and transfer of material are not simple processes, but are
very dependent on mechanical-chemical interactions. These
interactions are very sensitive to the energy dissipation at
the real areas of contact, hence to contact pressure.
As we have shown in previous work, environment has a
profound effect on these interactions. The ambient temperature
is important, as is the amount of water vapour
present at the interface. Relative humidity (RH) values,
however, give a poor indication of the actual amount of
water vapour present in the atmosphere. Therefore,
correlation between results and RH are poor unless
temperature is held constant. Thus as before we have
considered normalized water content of the atmosphere
(normalised to 15 8C, 15% RH) as a controlling factor.
High temperature increases the speed at which tape ages
and aged tape is more likely to generate debris [11]. The
aged tape shows a substantial increase in an extractable
binder of low molecular weight, which results in an increase
in friction and stiction. Absorbed water content affects the
mechanical and physical properties of polymeric binder
materials, usually; these materials become softer with
increasing water content and show higher friction values.
The objective of this study is to investigate the effect of
contact pressure and operating environment (temperature
and water content) on the head-tape interface in LTO system
and Travan5 system. By using what is essentially the same
media under exactly similar operating conditions, it is
possible to isolate the effects of contact pressure.