How to measure the flatness of glass?

1. The camber of tempered glass is calculated by measuring the distance between glass and steel wire with a straight thin steel wire as the reference;

2. Measure the waviness of tempered glass. Place tempered glass horizontally, use a 300 mm knife-edge ruler to cling to the bend of the glass surface vertically, with the direction perpendicular to the roller table of the tempering furnace, test the lower surface of the glass, and measure the distance between the glass and the knife-edge ruler with a feeler gauge;

3. Measurement of the warpage of tempered glass: place the tempered glass horizontally, use a 300 mm knife-edge ruler to cling to the edge of the glass vertically, with the direction perpendicular to the roller table of the tempering furnace and test the lower surface of the glass, and use a feeler to measure the distance between the glass and the knife-edge ruler.