Noncontact Viscosity Measurement of Molten Glass Using Laser-Generated Ultrasound for Process Control During Melting and Forming Operations

40879 November 13, 1996 Karta Technology, Inc. In almost all glass-manufacturing processes, production yield depends critically on the viscosity of the melt. Because the glass viscosity is a function of temperature, most active control systems monitor the temperature of the molten glass. However, temperature readings are not reliable for measuring viscosity. This project will develop a sensor that can measure the viscosity of molten glass directly, providing better process control. The sensor will use velocity and attenuation measurements of ultrasound pulses, as a function of frequency, to derive the viscosity of the glass. We propose to investigate a completely noncontact sensing approach, laser ultrasonics, which is very suitable for the hostile environment of glass manufacturing and can be used in forming and drawing operations without interfering with the process. Phase I will prove the feasibility of using laser ultrasound to measure the viscosity of molten glass, complemented with an experimental demonstration. Anticipated Results/Potential Commercial Applications as described by the awardee: The potential benefits of laser ultrasonics measurement of viscosity during glass production include better parameter control of the forming process, robust control under changes in glass batch composition, viscosity profiling in three dimensions, and fast scanning of the melt gob. A noncontact viscometer could be used for on-line process control of flat-glass, tubing, hollowware, fiberglass, and fiber-optic manufacturing.