Iridium is 6x harder and 8x stronger than platinum, this allows DENSO engineers to shrink the center electrode tip to only 0.4mm, the world’s smallest, and still maintain durability. This tiny electrode reduces the required voltage for the plug to fire resulting in improved firing performance. DENSO uses a patented Iridium alloy formula which employs over 90% Iridium, and small amounts of another material called Rhodium, which is added to even further reduce oxidation.
Also, a U-Groove has been cut inside the ground electrode to maintain the large volume of space required to form the nucleus of a flame. While still keeping the required voltage low, this technology enables excellent firing performance without increasing the spark gap.
The tip of the ground electrode has been cut to form a taper. This greatly improves firing performance by reducing “quenching,” or the absorption of spark energy by the electrode.
At first, the use of Iridium as an electrode material was impossible due to its extreme hardness and high melting point. Now, DENSO has developed a patented 360° laser welding process to firmly affix the Iridium material to the center electrode in a bond so reliable the electrode resists wear even in the harshest conditions.