Frequently Asked Questions...
What is the way of heating ?
There are two primary ways to heat temper glass -
horizontally or vertically.
Horizontal heating is accomplished by placing the parts on ceramic rollers in a
furnace that heats both surfaces of the parts with the quenching occurring
sequentially on either metal ringed or polymer ringed rollers in the quench zone
of the equipment.
Vertical heating may be accomplished by two major processes: By placing the
parts vertically in holding racks on overhead-type roller conveyors or by "tong"
type carriers (which hold the parts by clamping bars against the surface) on
overhead-type roller conveyors. Quenching is accomplished while the parts are
still in the same racks or carriers by transferring the rack or carrier to the
quench
zone of the equipment.
The horizontal heating method is preferred over the vertical heating method
because in the vertical method “slumping of the glass” may be caused or a slight
mark will be introduced from the rack. In addition, a “tong type” equipment will
cause a dimple and stress point to be formed on the surface of the glass.
What is the advantages of Tempered Glass ?
1) Tempered glass is 4 times stronger than Annealed Glass (Typical breaking
stress for Annealed Glass-6000 psi and that for Tempered Glass-24000 psi)
2) Typical Impact Velocity causing fracture: For Annealed Glass-30ft/sec. and
for Tempered Glass-60ft/sec.**
3) Withstands higher wind loads (a must for High Rise buildings) Tempered
glass has high resistance to uniform pressure and can thus be used on tall
buildings where one must consider the impact of high wind pressure
4) Can take heavier weights than annealed / ordinary glass of similar
thickness
5) Able to resist temperature differences (200 deg.F - 300 deg. F)
6) Even upon breakage, it fractures into small relatively harmless fragments thus reducing the likelihood of injury to people as there are no jagged or sharp edges.
7) The tempering process does not affect the clarity and transparency of glass.
** ¼” light 5 gm. missile, impact normal to surface..