Surface Flattening and Nanostructuring of Steel by Picosecond Pulsed Laser Irradiation

Tomoki Kobayashi, Hiroshi Sera, Tomohiro Wakabayashi, Haruyuki Endo, Yuichi Takushima, Jiwang Yan

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)


Steel is used as a mold material for press/injection molding of plastic products. High accuracy and releasing ability are required for a steel mold surface. This paper proposes a surface finishing method for steel molds by using picosecond pulsed laser irradiation. The process involves two steps: one is surface flattening by removing the surface asperity through laser ablation, and the other is forming nanoscale laser-induced periodic surface structures (LIPSS) on the flattened surface. The two steps are realized by using the same laser at controlled laser fluence and focus position. Experimental results showed that LIPSS was successfully formed after surface flattening under specific ranges of laser fluence and defocus length. Furthermore, plastic forming experiments demonstrated that a steel surface with LIPSS significantly decreased the effective contact area and, in turn, reduced the mold releasing force. These findings provide the possibility of fabricating high-performance steel molds by picosecond pulsed laser irradiation.

Original languageEnglish
Pages (from-to)217-224
Number of pages8
JournalNanomanufacturing and Metrology
Issue number4
Publication statusPublished - 2018 Dec 1


  • Mold releasing ability
  • Nanostructure
  • Picosecond pulsed laser
  • Plastic molding
  • Steel material
  • Surface flattening

ASJC Scopus subject areas

  • Industrial and Manufacturing Engineering
  • Mechanical Engineering
  • Materials Science (miscellaneous)


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