1. To measure the overall bow of tempered glass, place the glass on an inspection bench. Run a metal string line on the two edges of the glass and fasten the strings. Raise both ends of the string by using the feeler gauge of the same thickness. Use another feeler gauge to measure the gap between the midpoint of the glass and the metal string. The difference between the gap distance and the thickness of the elevating feeler gauge is the amount of deformation. Divide the amount of deformation by the length of the glass to calculate the overall bow of the tempered glass.
2. To measure the waviness of the tempered glass, place the tempered glass on an inspection bench. Press a 300 mm knife edge ruler vertically against the glass surface (about 200mm away from the edge of the glass) in a direction perpendicular to the direction of the conveyor rollers of the glass tempering furnace during operation. Measure the lower surface of the glass while it is being processed. Use the feeler gauge to measure the gap between the glass and the knife edge ruler.
3. To measure the warp of the glass, lay the tempered glass flat on an inspection bench. Press a 300 mm knife edge ruler vertically against the edge of the glass in a direction perpendicular to the direction of the tempering furnace rollers during processing. Measure the lower surface of the glass. Use the feeler gauge to measure the gap between the glass and the knife edge ruler (measure the amount of deformation within about 200mm along the edge of the glass).