Glass can be
machined on a lathe with glass-hard steel cutters, turning out shaped pieces in
the same way as from wood or metal. Glass is ground and polished using usual
abrasive powders, tools, and methods that have long been known and widely used
in the metalworking industry.
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| Glass Grinding |
Glass can be
founded from single silica sand which chemical formula is SiO2.
However, this requires a very high temperature (above 1700° C). Obtaining such
temperatures in industrial-type furnaces is associated with great difficulties.
Usual furnaces that use solid, liquid or gaseous fuels are not suitable for
this. For the melting of quartz sand, electric furnaces of special device or
burner are used, in which hydrogen is burned in a stream of oxygen. Molten
quartz sand is such a thick and viscous mass that it is difficult to remove air
bubbles from it and give the desired shape to the products.
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| Glass Machining |
In glassmaking,
only the purest varieties of quartz sand are used, in which the total amount of
pollution does not exceed 2–3%. Especially undesirable is the presence of iron,
which even in insignificant quantities (tenths of a percent) colors the glass
in a greenish color. If soda (Na2CO3) is added to the
sand, then it is possible to found the glass at a lower temperature (200 - 300°
lower). Such a melt will be less viscous (bubbles are easier to remove, and
products are easier to form). But! Such glass is soluble in water, and products
from it are subject to destruction under the influence of atmospheric effects.
To make the glass insoluble in water, a third component is brought in it -
lime, limestone or chalk. All of these three substances are characterized by
the same chemical formula - CaCO3.
