When heating a sheet of glass larger than 1500mm×1500mm and with a nearly square shape in the glass tempering machine, it is recommended to use a low-temperature and long heating time. This is because the heat absorption process of the glass in the glass tempering furnace starts from the edges and gradually moves to the centre area.
If the heating time is too short, the centre area of the glass will not absorb enough heat, resulting in either one of the following situations:
- The glass spontaneously explodes when leaving the furnace after completing the heating process.
- The glass bends into a spherical shape after the tempering process due to uneven heating.