Manufacturing 2

8/2/2019 Manufacturing 2

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By,Aaman Daredia

Joseph Chakkery

Alan Fernandes.


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Silica ( SiO2 ) Soda Lime

Cullets ( 25 % Broken Glass)

For Certain Glass Types: Metallic Oxides to add a colour

tint. Mg and Al to increase resistanceto atmospheric agents.


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Float glass Manufacture

Blown glass Manufacture


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Float glass is sheet glass made by floating moltenglass on a bed of molten tin. This method gives theglass uniform thickness and a very flat surface.

The molten glass spreads on the surface of the metaland produce a high quality, consistently level sheetof glass that is later heat polished.

The glass has nowave distortion and is now the

standard method for glass production; over 90% ofthe world production of flat glass is float glass.


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Batching of Raw Materials. Melting of Raw Materials in the Furnace. Drawing the molten glass onto the Tin Bath.

Cooling of the molten glass in the AnnealingLher. Q uality checks,automating cutting and storage.


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The main components,namely,soda lime glass,silica sand (73%) ,calcium oxide (9%) ,soda (13%)and magnesium(4%), are weighed and mixed

into batches to which recycled glass (cullet) isadded. The use of cullet reduces the

consumption of natural gas. The materials aretested and stored for later mixing undercomputerised control.


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The batched raw materials pass from amixing silo to a five-chambered furnace

where they become molten at a temperatureof approximately 1500C.


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The molten glassis floated" onto a bath of moltentin at a temperature of about 1000C. It forms aribbon with a working width of 3210 mm which isnormally between 3 and 25 mm thick. The glasswhich is highly viscous and the tin which is very fluiddo not mix and the contact surface between these

two materials is perfectly flat.


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On leaving the bath of molten tin, the glassnow at atemperature of 600C - has cooled down sufficiently topass to an annealing chamber called a lehr. The glass is

now hard enough to pass over rollers and is annealed,which modifies the internal stresses enabling it to be cuand worked in a predictable way and ensuring flatness

of the glass. As both surfaces are fire finished, they neeno grinding or polishing.


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After cooling, the glass undergoes rigorous qualitychecks and is washed. It is then cut into sheets ofsizes of up to 6000 mm x 3210 mm which are inturn stacked, stored and ready for transport.


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Float glass is used for glazing wherever fulltransparency is required in buildings.

It is used as a base material for safety glass,reflective and self-cleaning glass, amongothers.

It can be used in precision mechanics,especially where extreme surface flatness isrequired. E.g., for visual displays.


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Melting and refining Float bath

Blowing Annealing Inspection


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A ball of melted glass is placed on the end of ahollow iron tube. Air is then blow n into the tubeto shape the glass on the other end. Air can beblown in manually or by machine. The glass is

reheated often during this process so that it stayspliable. When the glass blower is finished with thepiece, it is allowed to cool and is then broken freefrom the blowing tube.


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Borosilicate Glass Commercial Glass

Glass Ceramics Glass fibre Lead glass Optical glass Bulletproof glass


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Most of us are more familiar with this type of glass in the form ofovenware and other heat-resisting ware, better known under thetrade name Pyrex. Borosilicate glass, the third major group, ismade mainly of silica (7080%) and boric oxide (7-13%) withsmaller amounts of the alkalis (sodium and potassium oxides) and

aluminium oxide. This type of glass has a relatively low alkalicontent and consequently has good chemical durability andthermal shock resistance (it doesn't break when changingtemperature q uickly.)


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Most of the glass we see around us in oureveryday lives in the form of bottles and jars,flat glass for windows or for drinking glasses

is known as commercial glass or soda-limeglass, as soda ash is used in its manufacture.


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Some of these "Glass ceramics", formedtypically from lithium aluminosilicate glass,are extremely resistant to thermal shock and

have found several applications where thisproperty is important, including cooker hobs,cooking ware, windows for gas or coal fires,

mirror substrates for astronomical telescopesand missile nose cones.


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Commonly known as lead crystal, lead glass isused to make a wide variety of decorative glassobjects.It is made by using lead oxide instead ofcalcium oxide, and potassium oxide instead of all

or most of the sodium oxide. Lead glass has a high refractive index making it

sparkle brightly and a relatively soft surface sothat it is easy to decorate by grinding, cutting

and engraving which highlights the crystal'sbrilliance making it popular for glasses,decanters and other decorative objects


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Optical glasses will be found in scientificinstruments, microscopes, fighter aircraft and

most commonly in spectacles.


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Bullet-resistant glass is a type of strong butoptically transparent material that is particularlyresistant to being penetrated when struck bybullets, but is not completely impenetrable.

Bullet-resistant glass is usually constructedusing polycarbonate, thermoplastic, and layersof laminated glass.

It is made from layers of polycarbonate (a toughtype of plastic), sandwiched in between pieces oftoughened glass. This sandwich of layers is calleda laminate.


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Manufacturing 2