Glass is manufactured through a process involving melting raw materials like silica sand, soda ash, limestone and cullet at high temperatures, then rapidly cooling to form an amorphous solid. The main raw materials are classified into glass formers, fluxes, modifiers and fining agents. Common glass types include soda-lime glass, borosilicate glass and lead glass. Glass products are formed through processes like float glass, fiber glass, tubing and are used as window glass, fiber insulation, laboratory equipment and more.

1. Presented by; M usman
khurram iqbal
Ahmad Naeem
Presented to; Dr. Asim

2. Glass Manufacturing

3. Contents
What is glass
Raw material
Manufacturing steps
Glass forming
Types and applications

4. An amorphous, rigid and brittle material,
typically transparent or translucent, made by
fusing sand with soda, lime, and sometimes
other ingredients; and cooling rapidly.
What is glass

5. Glass manufacturing materials can be divided
into 5 categories
1. Glass former
2. Flux
3. Modifier
4. Coloring agents
5. Fining agents
6. Cullet (broken glass pieces)
Raw Material

6. Glass former:
one of the most important components present
in any glass
Silica (SiO2),
boric oxide (B2O3) and
phosphoric oxide (P2O5) are the most
common type of glass formers present in
oxide glass
Raw material ……cont

7. The use of silica glass is wide but melting
temperature of silica is too high(1600-
1725ºC).
To reduce the processing temperature of
silica, different types of flux such as Na2O
and PbO can be used
Raw material
……cont

8. The addition of fluxes to silica reduces the
overall cost of glass processing but results in
degradation of properties.
Sodium carbonate and calcium carbonate are
common fluxes. Potash glass is more dense than
soda glass.
To overcome this problem, different property
modifiers or intermediates such as boron,
sodium, magnesium, titanium, and calcium can
be used to modify the properties of glass.
Raw material…. cont

9. Colorants are used to control the color in the
final glass.
The amount of iron oxides (impurities)
present in the glass results in unintentional
change in color of glass.
The other types of colorants used are gold
and silver. These types of colorants change
glass color by forming colloids in glasses
Raw material….
cont

10. As the raw materials melt and react inside the
furnace, carbon dioxide and water emission takes
place which causes formation of bubbles.
Fining agents such as arsenic, antimony oxides,
potassium and sodium nitrates are added to raw
materials to remove bubbles from the melt
The high temperature and low viscosity is maintained
to raise the gas bubbles at the upper surface of the
melt and hence removed from the melt.
Raw material….cont

11. • Fining is important because it controls the
homogeneity of glass by eliminating bubbles.

12. The manufacture of glass is in four phases:
(1) preparation of raw material,
(2) melting in a furnace,
(3) forming and
(4) finishing.
Manufacturing steps

13. Process flow diagram

14. Depending upon the applications, there are
different processes of forming the glass.
The most common type of glass forming
process can be categorized as:
1. Flat glass
2. Glass fibers
3. Glass tubing
Glass Forming

15. Flat glass, sheet glass, or plate glass is made
by two processes.
The processes are
float glass process and
rolled glass process
1) Flat glass

16. Ribbon of glass is made by pouring molten
glass from the furnace to a bed of molten
metal such as tin, lead and low melting point
alloys under controlled atmosphere.
Float glass process

17. In the drawing or rolling process, the
continuous stream of molten glass from a
furnace passes through a pair of water cooled
rollers
Rolled glass process

18. Fiberglass is available in two types
continuous glass fiber and
short glass fiber (glass wool).
The first one is used in fabrication of
composite materials and latter one is used for
thermal insulation.
2. Glass fibers

19. Continuous glass fiber is produced by drawing
molten glass through multiple orifices
Continuous glass fibers

20. In glass wool process , the molten glass is
ejected from a rotating head by centrifugal
spraying process
Short glass fiber

21. In this process, molten glass flows around a
rotating hollow cone-shaped or cylindrical
mandrel through which air is supplied
continuously to avoid the collapsing of glass
tube while the glass is drawn out by set of
rollers.
3. Glass tubing
In this process, molten glass flows around a rotating
hollow cone-shaped or cylindrical mandrel through
which air is supplied continuously to avoid the
collapsing of glass tube while the glass is drawn out by
set of rollers
Glass tubing

22. 1. Soda-lime glass
2. Fused silica glass
3. Lead glass
4. Borosilicate glass
Types and applications of glass

23. Main constituent of practically all commercial
glass is sand.
Sand by itself can be fused to produce glass but
the temperature at which this can be achieved is
about1700°C. Adding other minerals and
chemicals to sand can considerably reduce the
melting temperature.
The addition of sodium carbonate (Na2CO3),
known as soda ash, to produce a mixture of 75%
silica (SiO2) and 25% of sodium oxide (Na2O), will
reduce the temperature of fusion to about 800°C
due to sodium silicate.
Soda-lime process

24. However, a glass of this composition is water-
soluble and is known as water glass.
To give the glass stability, other chemicals like
calcium oxide (CaO) and magnesium oxide
(MgO) are needed.
These are obtained by adding limestone which
results in a pure inert glass.
Soda-lime glass is a mixture of sodium silicate
and calcium silicate.
Soda – lime glass(water glass)

25. Simplest type off glass, consists mainly of
silica
Made by heating silica to a molten liquid,the
liquid is then cooled rapidly to form an
amorphous solid
Fused silica glass

26. Commonly known as Crystal or lead crystal
Made by using lead oxide instead of calcium oxide,
and potassium oxide instead of all or most of the
sodium oxide
Glass containing at least 24% PbO can be described
as lead crystal. Glass containing less than 24% PbO,
is known simply as crystal glass.
Lead Glass

27. Lead glass has a high refractive index making it
sparkle brightly and a relatively soft surface
Lead glass

28. Glass in the form of ovenware and other heat
resisting ware, better known under the trade name
Pyrex.
Borosilicate glass (or sodium-borosilicate glass) is
made mainly of silica (70-80%) and boric oxide (7-
13%) with smaller amounts of the alkalis (sodium and
potassium oxides) and aluminium oxide.
As it doesn't break when changing temperature
quickly.
sodium borosilicate glass is widely used across the
chemical industry, pharmaceutical sector for laboratory
apparatus
Borosilicate Glass

29. The basic flat glass product that is the first result
of the float process.
It is common glass that tends to break into large,
jagged shards.
It is used in some end products and often in
double-glazed windows.
Also the starting material used to produce more
advanced products through further processing
such as laminating, toughening, coating, etc
Annealed Glass

30. Glass can fracture due to stress concentration.
To avoid the fracture of glass, local high compressive stresses are
induced near the surfaces.
This is done by thermal toughening of glass.
Heating the glass plate to 650ºC after which rapidly cooling the
outer surface by air blasts.
Due to which thin compressive layer is created at the outer
surface and the center of the glass becomes the region of tensile
stresses. This causes the self-equilibrium.
Toughened or tempered glass

31. The glasses used in glazed door and making
tabletops are made by this process and is
termed as toughened or safety glass.

32. Made of two or more layers of glass with one or more
"interlayers" of polymeric material bonded between the glass
layers.
Laminated glass is produced using one of two methods:
Poly Vinyl Butyral (PVB) laminated glass
(Ethyl Vinyl Acetate (EVA) or Polyurethane (PU) are also used)
Cast in Place (CIP) laminated glass is made by pouring a resin into
the space between two sheets of glass that are held parallel and
very close to each other.
Laminated glass

33. Safety and security
Rather than shattering on impact, laminated
glass is held
together by the interlayer. This reduces the
safety hazard
associated with shattered glass fragments.