1. The fault of the heating element in the glass tempering furnace will cause it not to work properly, resulting in uneven heating in the glass tempering furnace.

2. Failure or inaccurate calibration of the thermocouple(temperature sensor) in the glass tempering furnace can also lead to uneven heating in the tempering furnace. 

3. Damage to the SSR or SCR, causing uneven heating.

4. Poor grounding of the equipment, leading to significant interference and inaccurate temperature measurements by the thermocouple , resulting in uneven heating.

5. Failure of the equipment's PT platinum resistance, leading to inaccurate temperature measurements by the thermocouple, and causing uneven heating.

6. The glass is placed unreasonably on the rollers. Since ceramic rollers are poor heat conductors, repetitive use of a certain area of the heating furnace will lead to temperature reduction in the area. In the meantime, the area of ceramic rollers not carrying glass will have a relatively higher temperature, resulting in temperature differences between the areas and uneven heating for the glass. 

7. Poor edge sealing of the heating furnace will cause more local heat loss at the edges of the heating furnace, resulting in uneven heating in the glass tempering furnace.

8. Unreasonable heating process parameters setting for the equipment can also cause uneven heating in the tempering furnace