The effect of temperature and joining speed on the joining quality for conduction laser joining of metals to polymers

Laser joining of metals to polymers offers several advantages to produce lightweight hybrid assemblies. An important one is the exceptional control over the heat input which defines the temperature at the interface of the materials. Initially, the in-situ heating observation of PA inside ESEM is considered. Then, aluminum and polyamide are joined in an overlap configuration while the temperature was recorded simultaneously at different areas between the materials. The results show that due to excessive heat input, polyamide degrades and leaves bubbles in the melted area. Finally, the materials are laser joined with several joining speeds to investigate different cooling rates of the polyamide during the joining process. It is concluded that joining with high cooling rates generates an amorphous melted layer of the polyamide which is different from the semi-crystalline structure of the bulk. This difference acts as a stress concentration zone and reduces the shear strength of the assembly.