PURPOSE: To enhance the reliability of welding process simultaneously avoiding the troubles of solution control and immersion time control for removing Cr oxide film thereby enhancing the reliability in case of welding a metallic can by a method wherein only a part of the Cr oxide film formed on the surface of a metallic ring to be welded into the metallic can is mechanically removed by grinding process.

CONSTITUTION: When a metallic ring 1 made of stainless steel is fusion-sealed with glass 2, a Cr oxide film 5 is formed on over-all surface of the metallic ring 1. During the welding process of a metallic can 6, in order to remove the Cr oxide film 5 on the part to be welded i.e. the surface of flange part 1a of the metallic ring 1, a terminal after the glass fusion sealing process is fixed to be ground by a cylindrical grind stone 4 adhering to the surface of the flange 1a and turning above the terminal. Through these procedures, the metallic can 6 can be electric-resistance welded into the sealing terminal on the surface of the flange 1a as a part to be welded wherefrom the Cr oxide film 5 is removed.