Laser surface pretreatment of metal for joints of metal and dissimilar materials

Abstract

Joining technology of metal and dissimilar materials is attracting attention in various industrial fields. Especially in the automotive industry, the joining of metal and plastics is expected to be a key technology for weight reduction. A new joining technology of metal to plastics has been developed by laser surface pretreatment to metal. The pretreatment is done by a continuous wave (cw) single mode fiber laser. High energy density and high scanning speed are required for making characteristic surface shapes of metal that are suitable for joining. The characteristic shape is not just a simple corrugation, but has tunnel-like shapes, which is called as stitch anchor. In the present work, a laser beam of 10–30 μm in diameter is focused on the work piece. The intensity is more than 10 MW/cm2. To make stitch anchor, the laser beam is moved at more than 2 m/s using Galvano-mirrors. It is confirmed that the characteristic surface shape is not only good for metal-plastics joining, but also for metal-metal, metal-rubber, and metal-adhesive-metal joining.