Robotic wire-based friction stir additive manufacturing

High axial force requirement for existing friction stir additive manufacturing technologies is a substantial obstacle to manufacturing of complex reliable components by high-freedom robots. Here, we proposed a new robotic wire-based friction stir additive manufacturing (R-WFSAM) method, characterized by paraxial feeding wires and pre-plasticization process, to enable the formation of deposited layers with significantly low force. The spiral groove design on the screw tool facilitates the pre-plasticization of materials prior to deposition and the continuous extrusion of the material, reducing axial force and diminishing the reliance on high-stiffness equipment for solid-state relevant technologies. Fully dense aluminum alloy components on the 2D plane and 3D curved surface by hybrid position/force control were successfully manufactured. The sufficient material flow and material mixing behavior during deposition on the plane induced by the multi-pin design strengthened the interfacial bonding. Homogeneous and fine grains were also achieved due to severe plastic deformation. The RWFSAM Al-Si alloy component possessed an ultimate tensile strength of 230 +/- 5 MPa and an uniform elongation of 28.1 +/- 1.0 %, exhibiting excellent isotropic mechanical properties. This method provides a novel approach for manufacturing large-size complex structural components with high flexibility and field re-manufacturing.