Joining of polymer to metal using material extrusion additive manufacturing

This study investigates the joining of metal to polymer by material extrusion additive manufacturing. Direct joining by layered extrusion was used to fabricate hybrid single lap joints of acrylonitrile butadiene styrene (ABS) and aluminum alloy 5052. The influence of the printing speed, bed temperature, and nozzle Z-offset on the lap shear strength was studied experimentally. The interface between the two materials was also observed under scanning electron microscope, and the chemical state of the polymer after printing was analyzed using differential scanning calorimetry (DSC), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The results revealed that elevated bed temperature and pressure application through lowering the Z-offset promoted better polymer filling of the metal surface structure and improved the joint strength by mechanical interlocking. Also, long exposure time to the heated build plate corresponding to low printing speeds lowered the mechanical performance of the polymer bulk due to thermal degradation. Mechanical interlocking was the main joining mechanism, but under high bed temperatures where the carbonyl group had formed due to degradation, a (C-O-Al) chemical bond was detected.