Glass sheet must undergo fine edge grinding before loaded into the tempering furnace. Make sure that the glass surface is not scratched during the grinding process; glass with no edge grinding or fine grinding may lead to the risk of explosion in the oven during heating and cooling process as the result of stress concentration or uneven stress distribution, causing severe damage to the glass tempering furnace. 

When the sheet glass is loaded into the chamber with no edge grinding or only rough grinding, the edges could carry small glass particles that may fall on the rollers when being transported. Especially when the particles fall on the ceramic rollers inside the furnace, they will be sintered on the rollers under high temperature and the pressure of the glass sheet rolling forward. Glass being transported by them will be seriously pitted. This type of problem can only be resolved by shutting down the furnace and having the ceramic rollers thoroughly cleaned after cooling down. While the frequent downtime definitely increases the operating cost of the machine, it also results in adverse effects to the useful life of the tempering furnace.

Moreover, when glass that has not gone through fine edge grinding process is transported on the rollers, it will cause some degree of damage to the roller surface. Damages to the ceramic rollers will be permanent and irreparable. 

For the same reason, specially shaped glass or glass undergone cutting, drilling, and cold processing should have the edges finished by edge grinding or beveling treatment.