Wegner & Bretschneider
Spark plug and manufacturing process thereof
 A spark plug with a rivet-like tip center discharge electrode is obtained by melting powdery metal essentially consisting of noble metal Au, Ag and/or alloys thereof with Pd or the like charged in a small end bore formed at a discharge end bottom of a ceramic insulator then allowing to cool. Sealing and/or resistor incorporation together with setting (sealing) of a terminal rod may be done one-stepwise with the center electrode formation or two-stepwise after the center electrode formation. A resultant space in the center bore may be utilized for various purposes. 
NGK Spark Plug Co., Ltd.
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inventional inventional inventional
Kanemitsu Yasuhiko Shunichi
Nishio Suzuki Takagi