1. Fabricating debris on the roller conveyor of the glass tempering furnace will cause regular scratches in the glass surface. As the location of fabricating debris  is fixed, the scratches in the glass will show a regular pattern. We can check the state of the rollers in the heating oven and cooling section and tackle the issue accordingly.

2. If the Kevlar rope around the roller conveyor in the cooling section of the glass tempering furnace is damaged or has debris, the steel drive rollers in the tempering section will cause scratches in the surface of the glass when the glass is in motion. In that case, we must replace the damaged Kevlar rope and clean the debris in time.

3. The failure of the furnace door could also cause damage to the glass surface. The partial opening of the door  or the debris may have come into contact with the glass surface. If that happens, we should check the door for malfunction and adjust the opening height of the door.

4. When the heating elements or thermocouple in the upper part of the furnace come off, it may also cause different degrees of scratching on the glass surface. In that case, we must stop the furnace to repair the faulty heating element or thermocouple.