Why do spark plugs wear over time?

Spark plugs wear over time primarily due to the constant blast of electrical energy at the electrodes. When a spark plug operates, it generates a spark that ignites the air-fuel mixture in the combustion chamber. This process involves high temperatures and pressures, which can lead to significant wear at the electrodes. The electrical arc causes a form of erosion, where material is gradually worn away from the spark plug's electrodes. This erosion reduces the spark plug's effectiveness in creating a strong spark, which can ultimately affect engine performance.

While wear and tear from friction is a factor in many mechanical components, in the case of spark plugs, the electrical discharge and the resultant high temperatures are the predominant causes of wear. Overheating of the engine can exacerbate spark plug wear, but it is the direct effect of electrical energy on the electrodes that is the primary concern regarding their longevity. High operating pressure does not directly cause wear on the spark plug but can affect overall engine performance and efficiency.