/g38/g82/g81/g73/g76/g74/g88/g85/g68/g87/g76/g82/g81/g3/g20/g3/g177/g3/g53/g72/g86/g88/g79/g87/g86/g29/g3 The first configuration for discussion is the upper roller 440 F steel, annealed  and passivated and the lower roller material Ti6Al4V, anodized. This configuration matches that of a tested qualification unit [1,2]. A motivation for this test was to demonstrate that the test conditions selected for this work (i.e. the speed, load, misalignment angle, and duration) would produce the relevant wear phenomena. One test was completed using this configuration. Significant adhesive wear and plastic flow of material occurred throughout the test. After 78,000 cycles high vibrations were occurring, and the  test was stopped early of the targeted 90,000 cycles to avoid damage to the apparatus. The final roller  conditions for this test are provided in Figure 6(a). The upper steel roller lost 0.0710 g mass while the  lower Ti6Al4V roller gained 0.059 g mass. As a pair the rollers lost 0.011 g mass. Stylus profile  inspections of the tested upper roller revealed a material peak along one edge of the contact, likely from  plastic flow, reaching over 100 micrometer heights. Similar inspection of the tested lower roller revealedadded material in the contact region reached 60 micrometer of height. This test confirmed that the operating conditions selected for this study reproduced the relevant wear phenomena of the qualification test unit. /g38/g82/g81/g73/g76/g74/g88/g85/g68/g87/g76/g82/g81/g3 /g21/g3 /g177/g3 /g53/g72/g86/g88/g79/g87/g86/g29 The second configuration for discussion is the upper roller 440 C steel  hardened to HRC 58-60 and passivated and the lower roller anodized Ti6Al4V. The three tests completed  using this configuration all had similar wear behavior. Significant adhesive wear had occurred after 25 percent of the test duration. The final conditions of the rollers featured distinctive worn surface topographies and significant adhesive wear had occurred; see Figure 6(b). From profilometer inspections the steel roller wear valleys had typical depths of 15 micrometers. The Ti6Al4V roller had a region with material removed and just adjacent another region with material added. Mass measurements confirmed that in the net the steel rollers lost mass and Ti6Al4V rollers gained mass. The sizes of the valley features of the steel roller and the peak features of the Ti6Al4V roller for this configuration were of smaller magnitudes by a factor of two to three as compared to Configuration 1. This result is consistent with the  general trends observed in the earlier NESC study [3-4] that had quantified wear rates being less by order  of two to three for hardened 440C rollers compared to annealed 440 F rollers. /g38/g82/g81/g73/g76/g74/g88/g85/g68/g87/g76/g82/g81/g3/g22/g3/g177/g3/g53/g72/g86/g88/g79/g87/g86/g29/g3 The third configuration for discussion comprises one test with the upper roller  material polyimide and the lower roller anodized Ti6Al4V. The lower anodized roller abraded the upper  polyimide roller like a machining process. The test created a great amount of polyimide debris [Figure 6(c)], and the test was stopped after 38,000 cycles far short of the intended 90,000 cycle duration.   After cleaning with a soft-bristle brush, rollers look almost like the new condition. This material configuration might be suitable for situations where the polyimide wear debris could be tolerated, but it is not suited for the present application. /g38/g82/g81/g73/g76/g74/g88/g85/g68/g87/g76/g82/g81/g3/g23/g3/g177/g3/g53/g72/g86/g88/g79/g87/g86/g29/g3 The fourth configuration for discussion is the upper roller material of hardened  and passivated 440C steel with a solid lubricant bonded film. The bonded film was a commercially  available PTFE type with an inorganic binder. The product vendor considered the mean test pressure as  “uncomfortably close to” the binder strength limit. The lower roller material was anodized Ti6Al4V. One test comprising 83,000 cycles of this configuration was completed. The bonded film was abraded and worn away by the anodized surface of the lower roller. A great volume of powdery debris was formed and transported toward one edge of the roller contact by the sweeping action of the misaligned rollers [Figure 6(d)]. Once the bonded film was compromised, adhesive wear occurred with similar wear rate of uncoated rollers. It appears that the binder strength was indeed insufficient, per the concerns expressed by the product provider. This configuration is obviously not suited for the present application. 94