The shape and accuracy of electrode is one of vital factors of welding quality in spot welding process. The electrode was made with a conventional lathe in a staged shape, and the dimension and shape of wire groove was hardly controlled, which lead to "spark" or weak joint.

Using a CNC lathe, the axial shape of electrode could be built into a stress equalizing profile, and the radial dimension and shape could be controlled in small tolerance with economical efficiency , thus increase the welding quality.