MANUFACTURING METHOD OF SPARK PLUG AND MANUFACTURING APPARATUS OF SPARK PLUG

摘要

PROBLEM TO BE SOLVED: To suppress manufacturing cost of the whole manufacturing equipment of a spark plug and improve the safety of equipment by facilitating installation of such a testing container while improving evaluation precision of voltage resistance of an insulator used for a spark plug.SOLUTION: The manufacturing method of spark plug includes: (a) a process for forming a material including ceramics into a predetermined shape to obtain a molded body; (b) a process for obtaining an insulator by burning the molded body; and (c) a process for applying a predetermined voltage between two electrodes disposed with the insulator sandwiched in a container and evaluating voltage resistance of the insulator against the predetermined voltage. The process (c) includes a process for adjusting a pressure in the container to less than the atmospheric pressure.SELECTED DRAWING: Figure 5