An Instrument for Detecting Faults in Flat Glass

One method of making flat glass is the float process, which produces an endless ribbon of the finished product. The width of the ribbon is approximately 10 feet. The glass contains faults such as bubbles and stones, which are small pieces of refractory material from the glass-melting tank.

In order to assess the quality of the product and be able to cut it into pieces of optimum size, we need to know the number of faults and where they are. At present the glass is examined visually before the ribbon is cut, the inspectors marking each fault with a dab of ink so that after cutting, the pieces containing faults can easily be seen.

To avoid the usual disadvantages of subjective examination, particularly since production speeds are continually rising, there is a need for some form of automatic inspection. An instrument to do this has been developed and, although not yet in full scale use, prototype trials on the production line have been carried out.