Page 53 - Curriculum Visions Dynamic Book

(Above and right) Rolling is
used when glass with a texture is needed, for example, in flat glass used in bathroom windows. Rollers are made with special ridges. As the glass moves between them, the pattern is pressed into the glass.
(Above) Glass tubes are used for making thermometers.
3. Tubes and rods
Tubes and rods can be made in several ways. Essentially, glass is pushed through a hole
or allowed to fall from a hole over a special cone-shaped piece of metal called a mandrel. Compressed air flows through the mandrel, and that opens up the glass into a tube.
Glass tube and rod can be made extremely quickly by this method. Production rates can exceed 60 km/hr of tube from each machine.
(Left) Tubes and rods are drawn over a cylinder or cone called a mandrel. Air is blown through the mandrel, and that holds the tube open until the glass has solidified. Rods are also drawn, but no air pressure is used.
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