Diamond-like carbon (DLC) coatings were deposited using a commercial direct ion beam deposition technique on thin-film Al2O3–TiC inductive write heads. The coating thicknesses used were 5, 10, and 20 nm. Accelerated wear tests were conducted with metal particle tapes in a linear tape drive. Atomic force microscopy was used to image the thin-film regions to measure pole tip recession (PTR), relative wear of the pole tip with respect to the air bearing surface. It is found that the coating wears off of the head substrate to a significant extent in the first 1000 km of sliding distance. The coating is worn off the substrate long before it wears off of the thin-film region. The existence of the coating on the thin-film region provides close enough wear characteristics between the substrate and thin film that the two wear at similar rates. This results in little growth in pole tip recession. Early in the wear test, the coated substrate wears at a slightly higher rate than the DLC coated thin-film region due to the difference in tape contact pressure between the two materials; decreasing PTR is the result. As the coating on the substrate wears significantly, PTR begins to increase with sliding distance. Failure does not actually occur until the coating has worn off of the thin-film region. Near failure, the coating delaminates locally. Results indicate that coatings of 20 nm thickness may provide protection against PTR in future tape drives.

Web handling is germane to a diverse set of industries, including paper, polymer, textile, and sheet metal processing. Angular misalignment of the guides used to position a web in its transport system generates non-uniform in-plane forces that can result in transverse buckling of the web, even for misalignments as small as a fraction of a degree. In this paper, the state of stress, the associated in-plane deformation, out-of-plane vibration, and stability of webs with misaligned guides are investigated experimentally and theoretically. The onset of edge buckling, in which transverse corrugations are present along an entire free edge or are localized near a guide, is governed by the stability of a relatively high mode of the nominally aligned web. Two models of common web transport components—termed “free sliding” and “edge guided” —are developed and discussed in the light of laboratory measurements for predicting and bounding critical buckling angles.

A foil bearing is formed when a flexible material passes over a stationary rigid surface and entrains a thin layer of air that lubricates the relative motion. Some applications include the transport of magnetic tape, and the manufacturing of paper and metal sheets. In each case, the transverse displacement of the moving medium couples with the air film’s pressure, requiring simultaneous solution of the governing elastic and lubrication equations. Such simulations can become computationally intensive, particularly when the model incorporates the finite width effects of side flow and cross-web deformation. Of primary focus in this paper is the development of an efficient numerical algorithm for such simulations. Two improvements in that regard are discussed: inexact Newton iteration and adaptive nodal point placement. In two case studies adapted from the literature, implementation of these techniques offered roughly five-fold improvements in computational effort when the equilibrium film thickness, air pressure, and web displacement were calculated. The key advantages of the approach are a more rapid convergence rate, and the opportunity to use fewer degrees of freedom in describing the pressure and film thickness since the nodes are assigned automatically during iteration to regions where the solution is most rapidly changing.

The hedtape spacing for high-performance tape drives is strongly affected by the geometry of the head contour. In particular, head curvature, head width, bleed slot dimensions and bleed slot edge quality can enhance or negatively affect the performance of the head/tap interface. In this paper we study the effect of edge fabrication irregularities on the performance of the headhape interface for the c~s e of single and double module tape heads.Experimental Setup

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