Taking the radiation glass tempering furnace for example, the set heating time (the time glass stays in the furnace) for each millimeter of thickness is usually about 40 to 50 seconds. For instance: the heating time for a 6mm glass pane is approximately 6×40 seconds＝240 seconds. The set heating time may vary according to the actual situations such as the size of the glass pane and processing quantity of a single batch. Adjustments are required in actual operations for the best results.