METHOD OF MANUFACTURING SPARK PLUG

摘要

Disclosed is a method of manufacturing a spark plug with an insulator of a low mechanical strength, in which the lowering of yield and productivity can be avoided. In a second process, the insulator (12) is heated to the softening temperature of first to third powder materials (16P, 17P, 18P) or higher, a terminal electrode (15) is inserted to a predetermined position, and a first conductive seal material layer (16) is made from the first powder material (16P), a resistor (17) is made from the second powder material (17P), and a second conductive seal material layer (18) from the third powder material (18P). Furthermore, in this second process, a speed at which the terminal electrode (15) is inserted is reduced during the period from the start to the end.