Toughened glass

Toughened glass Glass is naturally fragile. Thanks to the toughening process, the internal stresses within its structure change, which results in an increase in its bending strength. Toughened glass means safety.
When it breaks, the pane is shattered into tiny pieces with blunt edges.

This characteristic makes toughened glass particularly suited for use in highly sensitive places, with a high risk of being broken or exposed to high insolation – which means a big increase of internal thermal stresses.

Advantages

    • bending strength is five times higher in comparison with non-toughened glass,
    • resistance to thermal shock and heating caused by solar radiation,
    • decreased risk of injury when the pane is broken.

    Toughened window panes:

    • in the shape of single formats or double and triple glazing,
    • with holes and cuttings,
    • with chamfered, ground or pol-ished edges;
    • in triangular, rectangular and polygonal shapes, arcs and circles;
    • covered with silicon coatings and enamelled,
    • silk screen printed.
Toughening
type
Glass thickness
[mm]
Minimum dimensions
[mm]
Maximum dimensions
[mm] T-thermofloat
Standard

4

5

6-19

100×250

100×250

100×250

1700×2500 (T:1500×2500)

3200×7000 (T:2300×3800)

3200×7000

Directional hardening

An inseparable component of the toughening process is the so-called glass waviness.
PRESS GLASS informs all customers that this effect can occur, in order to be fair in service.
The waviness effect is of particular importance if glass panes are assembled in building
facades, especially with big glazed surfaces. It is visualised by a distortion of the view
reflected in the facade. To decrease the distortion ef-fect of a reflected picture,
it is suggested that directional toughening is made. It means that e.g. in the case of
toughening along the height, waviness will occur perpendicularly to this dimension.

Semi-toughened glass

Semi-toughened glass differs from the toughened glass by the kind of breaking netting,
which occurs during glass panel damage. Due to its breaking characteristic, the panel assembled
in the frame stays there after the damage, which protects against injury. Thanks to this feature,
TVG is starting to become interesting as an alternative for toughened. However, semi-toughened glass
is not counted among the types of safety glass.

Glass thickness
[mm] T-Thermofloat
Minimum dimensions
[mm]
Maximum dimensions
[mm]

4

5

6-19 (T:6-10)

200×450

200×450

200×450

1700×2500 (T:1500×2500)

3200×7000 (T: 2300×3800)

3200×7000

Heat Soak Test

Heat Soak TestThe manufacturing process of float glass is done by the smelting of separate ingredients. Molten glass is poured out in special baths, and then formed to the required thickness in a floating process on the surface of melted tin, where it cools down.
There exists a risk during this process that inclusions of nickel sulfide will occur. This phenomenon causes an increase of internal stress in the hardened glass, which could finally lead to self-breaking.
Even though this phenomenon occurs extremely rarely, one must allow for this possibility. It is suggested that the toughened glass is put under pre-heating process, during which the glass panes which have pollution content are eliminated from the shipment.

PRESS GLASS Company offers the possibility of carrying out an extra glass check by means of the Heat Soak Test method

Machining of edges

Depending on the customer’s request, before starting the toughening process,
the glass must undergo the machining process i.e. cutting, drilling, grinding
or grinding and polishing together. Safety glass which is tempered, undergoes
checking according to the Polish standard EN 12150- 1 and the Polish technical
criteria of KT ISiC 027/S/2003.
Hardened safety glass produced by PRESS GLASS can not undergo further machining. All requirements have to be presented together with the order for tempered glass.

If there is no additional description all hardened glass panes up to 8mm in thickness are produced by PRESS GLASS with blunt edges (it is included in the price). Glass panes which are thicker than 8 mm have matt grinded edges (grinding is not included in the price and should be added to the price of tempered glass).

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