Overflow downdraw method

Question 1

When was the overflow downdraw method created? What’s it used for?

Answer 1

~ 1960’s

~ used for very thin flat panel displays

Question 2

How does the overflow downdraw method work?

Answer 2

1. molten glass overflows from a supply trough, flows down, adhering to the two converging sides.
2. the molten glass re-joins (fuses) at the tapered bottom, where it is drawn away in sheet form
3. exterior surfaces are pristine, formed only in contact with air
4. air jets, which can heat or cool, control glass temp and therefore viscosity. Feedbak control of laser thickness monitors to air-jet temp, achieves a setpoint thickness