Effect of Micro Pits on Workpiece Surface on Friction Behavior in Metal Forming

Zhrgang Wang, Kuniaki Dohda, Yoshio Haruyama, Nobuyasu Yokoi

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


The purpose of this paper is to clarify the mechanism and lubricating effects of the outflow behavior of lubricant trapped in pits. The pits regularly arranged on a workpiece surface were produced by coining a die surface topograghy. The effects of pit size, array and area ratio of pits on the friction behavior were investigated by using a rolling-type tribometer. Lubricant flows out from oil pits in the direction of the friction stress. The outflow trace becomes deeper for the lubricant of higher viscosity or for the annealed workpiece. With increasing the area ratio of pits or decreasing the pit size or arranging the pits to cross array, the outflow lubricant from pits covers wider surface area and the lubricating effects of the pits become larger. The lubricating effects of the pit also become larger with decreasing viscosity of the lubricant or roughness of the surface around the pit and with increasing the hardness of the workpiece.

Original languageEnglish (US)
Pages (from-to)3408-3415
Number of pages8
JournalNihon Kikai Gakkai Ronbunshu, C Hen/Transactions of the Japan Society of Mechanical Engineers, Part C
Issue number636
StatePublished - 1999


  • Area Ratio of Pit
  • Friction Coefficient
  • Hardness of Workpiece
  • Oil Pit
  • Pit Array
  • Pit Size
  • Plastic Forming
  • Tribology

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Industrial and Manufacturing Engineering


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