Patent ID: 8164021

Claim:
An electrically assisted friction stir welding apparatus for reducing required downward forces on a workpiece during friction stir welding, the apparatus comprising: a tool comprising: a casing; a pin for contacting said workpiece, the pin extending through the casing, and mounted for axial rotation with respect to the tool; a motor for rotating the pin; a resistive heating circuit for heating the pin and for creating a localized heated zone on said workpiece, the resistive heating circuit comprising: a power source; a positive junction connected to the casing; and a negative return junction defining the localized heated zone, wherein the negative return junction comprises: a first electrical contact positioned on said workpiece; and a second electrical contact positioned on said workpiece, wherein when the pin contacts said workpiece, the pin is substantially halfway between the first electrical contact and the second electrical contact, wherein in the negative return junction, the first electrical contact comprises a first elongated plate, the second electrical contact comprises a second elongated plate, the first elongated plate and the second elongated plate positioned on said workpiece.