A pretreatment method for pretreating components, which are each formed of at least two different materials, prior to a coating process. The pretreatment method includes the steps: alkaline degreasing; chemical pickling in a first pickling medium; anodic pickling in a second pickling medium; and cathodic degreasing.

Disclosed is a method for manufacturing a spark plug in which a tip is welded to a ground electrode. After the tip is welded to a distal end portion of the ground electrode, polishing treatment or grinding treatment is performed on at least a part of an edge region of a distal end face of the ground electrode. After the polishing or grinding treatment, an image of the distal end face of the ground electrode and the tip is taken with the use of reflected light and then analyzed by image processing.

A device for cleaning ionizing electrodes includes a coil spring fixedly mounted at opposite ends, and an ionizing electrode operable by an actuator plunger for reciprocating movement relative to an axis of the coil spring along a line that extends from an outer periphery of the spring toward an inner periphery thereof, whereby during each reciprocating movement a tip of the electrode penetrates a complete cross-section of the coil spring so as to intersect the adjacent coils at opposing extremities thereof each of which is thereby able to collect dust and other waste deposits from the electrode.

A device for cleaning ionizing electrodes includes a coil spring fixedly mounted at opposite ends, and an ionizing electrode operable by an actuator plunger for reciprocating movement relative to an axis of the coil spring along a line that extends from an outer periphery of the spring toward an inner periphery thereof, whereby during each reciprocating movement a tip of the electrode penetrates a complete cross-section of the coil spring so as to intersect the adjacent coils at opposing extremities thereof each of which is thereby able to collect dust and other waste deposits from the electrode.

A pretreatment method for pretreating components, which are each formed of at least two different materials, prior to a coating process. The pretreatment method includes the steps: alkaline degreasing; chemical pickling in a first pickling medium; anodic pickling in a second pickling medium; and cathodic degreasing.