The most popular process for architectural
glass manufacturing today is the PPG process which was invented by Sir Alistair
Pilkington in 1952. This process includes five main stages by mixing multiple
The first stage
is melting and refining process which involves mixing Silica Sands SIO2,
Sodium Oxide Na2O, Calcium oxide CaO, Dolomite MgO, and Feldspar Al2O3
in a furnace and heat it up to 1500 degree Celsius. These material are used to
produce colorless glass and different oxides are added to achieve a specific
desired color. The most common oxides used are Oxides
of Nickel & Cobalt NiO & CoO to give a grey tinted color, oxide of
Selenium SeO to give a Bronze tinted color, oxides of iron Fe2O3
to give a green tinted color, and oxides of Cobalt CoO to give a blue tinted color.
reduce the melting point of the mix, broken glass (cullet) is added which
increases the energy consumption efficiency of the process.
stage is Float bath where glass flows over the refractory spout from the
furnace to a molten tin mirror-like surface. The flux enters the Float bath at
1100 degree Celsius and comes out of at as 600 degrees as solid ribbons.
The third stage
is Coating which is essential in manipulating the optical properties of the
glass. Coating is applied by multiple high temperature technologies and the
most common one nowadays is the Chemical Vapour Deposition (CVD). The CVD allow
us to apply multiple coatings on the glass ribbon.
fourth stage is Annealing to remove the internal stresses as the glass
cools to make the cutting process more feasible
The final stage
is cutting the glass with a diamond steels trim off selvedge or an equivalent
course, all these stages has to go through a quality check inspection. The
inspection process helps discovers any failures in the upstream process (such
as air bubbles that were not removed during the refining process) and allow the
downstream processes to steer round the flaws. After the completion of all
these processes, the product is then sold to external companies for their use.