How is a spark plug composed?

Spark plugs generally consist of center electrodes, side electrodes, threaded parts, insulators, spark plug shells, joints, seals, etc.
Center electrode: It is the electrode located in the center of the spark plug. The power from the high-voltage wire is transported to this part and uses the gap between the electrodes on the same side to generate sparks. The electrodes of high-performance spark plugs are finely machined and welded to platinum. In order to quickly discharge a large amount of heat energy, the center electrode of some spark plugs is also equipped with an electrode copper sheet inside the insulator.
Side electrode: The side electrode is the electrode connected to the threaded part of the spark plug, and is connected to ground through the thread. High-performance spark plugs also cut a very fine groove on the surface of the side electrode to make it easier to generate sparks.
Threaded part: The threaded part is mainly used to fix the spark plug, support the side electrode, and also has a heat dissipation function. Different types of spark plugs or the same type of spark plugs are used in different engines, and their thread diameters and thread lengths are different. Therefore, the same type of spark plugs will also be classified into finer categories depending on the car model.
Insulator: Insulator not only has supporting properties, but also prevents the leakage of electrical energy. Between the joint and the spark plug shell, in order to extend the insulation distance and reduce the impact of dust and moisture on leakage, the insulator is designed in a folded skirt shape.
Gasket: The main function of the gasket is to ensure a good seal between the spark plug and the cylinder when the spark plug is tightened. When the same spark plug is screwed on and removed repeatedly, the sealing effect of the gasket will be weakened. The electrode part of the spark plug is the focus of use and maintenance.
The shapes of the ends of the center electrode and side electrodes and the gap formed between the two electrodes are important factors affecting the ignition of the spark plug. Therefore, when judging whether the spark plug can be used, first visually inspect whether its shape is intact and check whether the gap is appropriate. Generally, a thickness gauge can be used to measure the gap of the spark plug.