Improvement of production efficiency and optimization of exit-hole–free FSSW joints using adhesive-bonded consumable pin and lubrication

This work presents an optimum methodology for producing friction stir spot welding (FSSW) joints using a detachable consumable pin. The study is carried out by welding two AA6061-T6 sheets using a consumable pin of the same material attached to the H13 steel tool. Three methods for attaching the consumable pin to the tool are explored: (1) push-fitting the pin in an indentation on the tool, (2) adhesively bonding the pin to the tool with a cyanoacrylate adhesive, and (3) adhesively bonding the pin to the tool with a thermosetting glue. After welding, the pin gets detached and assimilated into the workpiece. Cyanoacrylate adhesive–bonded consumable pin was the most effective in producing exit-hole–free FSSW joints with good joint strength. The use of lubricants along with adhesive-bonded consumable pins resulted in a reduction of energy requirement by 35 − 42% without compromising joint strength. Optimization was carried out using data from experiments as well as finite element method simulations. For simulating the lap shear test, the Cockcroft-Latham damage model was used. The optimum process parameters for obtaining the maximum joint strength were a rotational speed of 900 revolutions per minute and a plunge rate of 15 mm/min. Based on the study, a strategy for batch production is also proposed for enhancing productivity.