Patent ID: 8517786

Claim:
A method of producing a spark plug which comprises: a cylindrical metal shell; a cylindrical insulator fitted in the metal shell and including a front end portion exposed from a front end portion of the metal shell; a center electrode which is disposed within the insulator and which includes a front end portion exposed from the front end portion of the insulator and a metal tip which is secured to the front end portion of the center electrode through welding; and a ground electrode which includes a proximal end portion joined to the metal shell and a distal end portion disposed to be spaced apart from the metal tip in a radial direction in such a manner that a predetermined spark discharge gap is formed between the distal end portion of the ground electrode and the metal tip of the center electrode, the method comprising: welding a ground electrode tip to a distal end portion of the ground electrode in a position which faces the center electrode; thereafter, positioning the metal tip on a predetermined position of the front end portion of the center electrode in a radial direction relative to a center axis of the center electrode, thereby forming the predetermined spark discharge gap between the metal tip and the distal end portion of the ground electrode whose proximal end portion is previously joined to the metal shell; and then welding the metal tip to the front end portion of the center electrode after positioning step.