Denso past and present patented technologies make denso iridium, denso iridium spark plug, the best plugs you
can buy today. The U-groove design, Iridium alloy, and lazer welding process are unique
to DENSO, giving your car the highest level of performance achievable by a spark plug.
The U-Groove Design
In 1972, we received a patent for the popular U-Groove ground electrode design. This
electrode was developed to meet the demand for improved ignitability, which is necessary
for an increase of efficiency in emission gas purification and fuel consumption. The
U-Groove gives the flame a groove to grow in, thereby creating a larger flame front for
a more complete combustion even in the case of lean air-fuel mixture. A conventional,
flat ground electrode design of regular plugs crushes the flame preventing full spark potential.
In a never-ending effort to improve upon success, DENSO developed an Iridium alloy that is
superior to platinum based on hardness, strength and melting point. The new Iridium alloy is
composed primarily of Iridium with rhodium mixed in for oxidation wear. Pure Iridium has a
melting point of almost 700?C higher than platinum, and had the greatest potential for
resistances against wear. Iridium by itself is susceptible to oxidation wear at temperatures
over 900?C, however, ordinary driving around town an engine would never reach these temperatures.
Further testing proved that Iridium alone would not meet DENSO's demanding standards. After
testing other pure metals combined with Iridium, rhodium proved to be the best choice to meet
the needs of DENSO's spark plug engineers.
Laser Welding Process
DENSO's Iridium Alloy had all of the qualities to produce the world's best spark plug, but
conventional tooling prevented DENSO from mass manufacturing. Due to the high melting point
there wasn't a welding process hot enough to join the Iridium tip to the nickel base. Necessity
to melt the Iridium to the nickel base forced DENSO to pioneer its third patent, the 360? Laser
Welding Process, to provide a seal so reliable; the electrode resists wear even in the worst
Ultra Fine Electrode
By harnessing the power of Iridium, DENSO is suddenly able to shrink the surface area of the
center electrode - the critical component of a spark plug. Unlike a typical platinum plug that
has a 1.1mm diameter center electrode, DENSO Iridium Power plugs have the world's smallest
center electrode measuring 0.4mm in diameter. This means that the voltage requirements are
decreased while firing performance is greatly improved.
For more information on DENSO, visit their website at Denso iridium spark plug