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Toughened glass
1. MATERIAL DOCUMENTATION - TYPES OF GLASSES
ABSTRACT
Toughened or tempered glass is a type
of safety glass processed by
controlled thermal or chemical treatments to
increase its strength compared with normal
glass.
SHAROON
SHAMITHA
ZEESHAN
R.PRAMOD
BUILDING CONSTRUCTION
MATERIALSTOUGHENED GLASS
2. INTRODUCTION
• Toughened glass is also known as Tempered glass.
• Toughened or tempered glass is a type of safety glass processed by
controlled thermal or chemical treatments to increase its strength
compared with normal glass.
• Tempering puts the outer surfaces into compression and the inner
surfaces into tension.
• Such stresses cause the glass, when broken, to crumble into small
granular chunks instead of splintering into jagged shards.
• The granular chunks are less likely to cause injury.
3. HISTORY
• The first patent on tempered glass was held by chemist Rudolph A.
Seiden, born in 1900 in Austria.
• Though the underlying mechanism was not known at the time, the
effects of "tempering" glass have been known for centuries Its
popularity has increased in recent decades because of its use in the
automobile and construction industries, as well as in microwaveable
glassware.
• Among the most common current uses are for side and rear windows
and windshields in automobiles, display cases, patio doors, and
shower doors.
4. PROPERTIES
• Toughened glass is physically and thermally stronger than regular glass.
• The greater contraction of the inner layer during manufacturing induces
compressive stresses in the surface of the glass balanced by tensile stresses
in the body of the glass.
• For glass to be considered toughened, this compressive stress on the
surface of the glass should be a minimum of 69 MPa.
• For it to be considered safety glass, the surface compressive stress should
exceed 100 MPa.
• The greater the surface stress, the smaller the glass particles will be when
broken Any cutting or grinding must be done prior to tempering.
5. MANUFACTURING
• Cut the glass into the desired shape first.
• Inspect the glass for imperfections.
• Sand the cut edges smooth.
• Wash the glass.
• Heat the glass in a tempering oven(600 Degrees Celsius)
• Quench the glass to cool it.
6.
7. Thickness (mm)-2.8, 3 ,4 ,5, 6 ,8 ,10, 12 ,15 ,19, 22, 25.
Monolithic types- a. Transparent,
b. Bodily coloured,
c. Colourfully glazed,
d. Film plated,
e. Toughened glass Combination,
f. Toughened insulating glass,
g. Toughened laminated glass,
h. Toughened insulating laminated glass.
Max size possible(mm) - 5100 x 3200.
Min. size possible (mm) - 300 x 300.
8. SAFETY
• Through the quenching process, the inside of toughened
glass possesses the compressive stress, it will with stand
the impact force to certain extent, even though it
encountered greater load of impact and broke, its
fragments seemed to lot of tiny particles with obtuse angle
that hardly would do any harm to human body.
• While with the fragments of ordinary glass, they are
similar to large size broken sharp pieces easily causing
serious injuries to the people.
11. USES
•Toughened glass is used when strength, thermal resistance, and
safety are important considerations.
•The most commonly encountered tempered glass is that used
for side and rear windows in automobiles It is used for its
characteristic of shattering into small cubes rather than large
shards and is sometimes referred to as safety glass in this context
•Toughened glass is also used in buildings for unframed
assemblies (such as frameless doors), structurally loaded
applications, and any other application that would become
dangerous in the event of human impact.
Balcony doors, athletic facilities, swimming pools, facades,
shower doors .
12. The term "toughened glass" is generally used to describe fully tempered glass
but is sometimes used to describe heat- strengthened glass as both types
undergo a thermal "toughening" process.
There are two main types of heat-treated glass: heat- strengthened and fully
tempered.
Heat-strengthened glass is twice as strong as annealed glass while fully
tempered glass has typically four to six times the strength of annealed glass and
withstands heating in microwave ovens.
The difference is the residual stress in the edge and glass surface It is important
to note that the tempering process does not change the stiffness of the glass.
13. DISADVANTAGES
• Toughened glass must be cut to size or pressed to shape
before toughening and cannot be re-worked once
toughened.
• Polishing the edges or drilling holes in the glass is carried out
before the toughening process starts.
• Because of the balanced stresses in the glass, damage to the
glass will eventually result in the glass shattering into
thumbnail-sized pieces.
