The ability of solid lubricant (graphite) films to withstand repeated contact with a deforming cold or hot aluminum workpiece was investigated by three techniques. Ring compression very readily indicated the gradual wear of the film, but sliding at the interface was limited and tendencies to tool pick-up did not show up. Plane strain compression was much more useful in this respect; changes in the edge-profile of the compressed zone proved to be a sensitive indicator of friction, obviating the need for force measurements. Twist compression imposed the most severe conditions. In all instances, a sandblasted tool surface provided better lubricant retention than a polished one.

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