Laser structuring as a preparation for a metal plastic joint

Abstract

Lasers are a known tool to create different surface structures. In this paper, we describe a flexible surface structuring method for metals using a thin disk nanosecond laser. These structures are well suited for creating strong metal/plastic joints which lack glue, adhesives, or additional mechanical fasteners.When using a high-power short-pulse laser for joining metal and plastics, the first processing step generates a microstructure on the surface of the metal. Short laser pulses with high peak powers create high energy densities which lead to both a partial evaporation and a partial melting of the material. The short pulse and energy transfer times lead to a nearly immediate freezing of the molten mass. The vaporizing gas pressure lifts some of the melted material at the laser spot, and the metal freezes in barbed shaped edge beads. Using a special scanner movement, and the right set of laser parameters, it is possible to create structure depths ranging from a few micrometers to a few millimeters. The resulting structure consists of many small undercuts and, depending on the demands, the generated structure can be either direction-dependent or direction independent. By using laser pulses in the nanosecond range, the material temperature always remains low enough to avoid bulk structural changes to the material itself. With the TRUMPF TruMicro 7000 series laser’s ability to dynamically change pulse energy, the treatment of various metals with an identical optical system is possible.Additionally, a brief description of the plastic-metal joining method is described.Lasers are a known tool to create different surface structures. In this paper, we describe a flexible surface structuring method for metals using a thin disk nanosecond laser. These structures are well suited for creating strong metal/plastic joints which lack glue, adhesives, or additional mechanical fasteners.When using a high-power short-pulse laser for joining metal and plastics, the first processing step generates a microstructure on the surface of the metal. Short laser pulses with high peak powers create high energy densities which lead to both a partial evaporation and a partial melting of the material. The short pulse and energy transfer times lead to a nearly immediate freezing of the molten mass. The vaporizing gas pressure lifts some of the melted material at the laser spot, and the metal freezes in barbed shaped edge beads. Using a special scanner movement, and the right set of laser parameters, it is possible to create structure depths ranging from a few micrometers to a few millimeters. The...