The Self-Cleaning cycle uses very high heat to burn away soil and grease. During the cycle, the oven gets much hotter than it does for normal baking or broiling. This high heat breaks up the soil or grease and burns it away.
The graph at the right is representative of a normal, 3-hourSelf-Cleaning cycle. Note that the heating stops when the 3-hour setting is up, but it takes longer for the oven to cool enough to unlock.