So many works have been done on the slidingwear of cast iron, but still left a few questionable points.
  In this work, the sliding surface and the powders produced during wear process were observed and from the observation, the mechanism of dry sliding wear of cast iron was examined. And further, the relation between wear mechanism and reproducibility of wear loss amount or volume was studied.
  Results are summarized as follows.
  (1) In the oxidation wear range, conventionally called, plastic deformation due to frictional force is observed on the sliding surface. It is named that the layer of plastic displacement and of plastic flow.
  (2) In the range of mechanical wear, wear develops by breaking out from the crack propagating from the both end of graphite flake to adjacent graphite or to the surface.
  (3) In the range of adhesion wear, conventionally called, wear develops by breaking out from the cracks on the sliding surface which are the results of thermal stress generated by frictional heat. It is named the high temperature destruction wear.
(4) Study is done within the range of preferable reproducibility in wear loss. In the lighter load and slower velocity range than oxidation wear limit, as slide distance increases, wear mechanism changes from oxidation type to mechanical one, but mechanical wear does not change with increase of slide distance.