| 摘要 |
PROBLEM TO BE SOLVED: To provide a manufacturing method of a spark plug capable of preventing exfoliation of a zinc-plated layer formed on a grounding electrode without lowering strength thereof at low cost, while improving productivity. SOLUTION: A metal fitting assembly 200 formed by connecting one end 42 of the grounding electrode 4 to a metal fitting main body 1 is prepared, and a zinc-plated layer 141 containing zinc as a main component is formed on a whole surface of the metal fitting assembly 200. The grounding electrode 4 having the zinc-plated layer 141 is heated so that at least temperature at a side part of the other end part M1 reaches 700°C or higher and less than 1,000°C, whereby, a part of the zinc-plated layer 141 is alloyed with the surface of the grounding electrode 4, and a remaining part is removed by evaporation. COPYRIGHT: (C)2006,JPO&NCIPI
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