Laser based process chain to use LIPSS on forming tools

Friction during forming is conventionally reduced using mineral oil-based lubricants. From ecological and economic points of view, alternative lubricants are of great interest. The focus is on tools' surface functionalization by laser-induced periodic surface structures (LIPSS) creating hydrophilic surfaces potentially enabling water as lubricant. However, these structures must be protected from direct tribological contact due to wear. For this purpose, dimples are created by laser ablation onto the contact surface of strip drawing tools made of X153CrMoV12. Their bottoms are smoothed by laser polishing, the tool is hardened by laser hardening and finally the LIPSS are applied to the bottom surfaces. Using a combination of various pulsed and continuous laser processes, it has thus been proven that it is possible to harden the surfaces in contact while retaining the hydrophilic properties of LIPSS, which are protected from direct contact, and simultaneously keeping the distortion of the tools within tolerable range.