How is glass made

A powerpoint presentation on how glass is made.

1. Submitted by : Amarjeet Singh (K15914) Devesh Vijay (K15918) Submitted to : Dr. K M Sharma How is glass made ?

2. CONTENT Introduction Glass Ingredients Glass Making Process Glass Shaping Glass Types Glass heat treatment Glass Advantages Glass Disadvantages

3. Introduction Definition of glass : Solid material that is usually transparent and breaks easily. Glass is formed by fusing sand( SiO2 ), sodium carbonate( Na2CO2) , and calcium carbonate( CaCO3) under extreme heat. Glass is used for making windows, eye glasses, and bottles etc.

4. Percent of ingredients in glass Silica sand 72 % Soda ash 17 % Lime 5 % Other 6 %

5. Glass Making Process In a commercial glass plant, sand is mixed with waste glass (from  recycling  collections), soda ash (sodium carbonate), and limestone (calcium carbonate) and heated in a furnace. The soda reduces the sand's melting point, which helps to save  energy  during manufacture, but it has an unfortunate drawback: it produces a kind of glass that would dissolve in  water ! The limestone is added to stop that happening. The end-product is called  soda-lime-silica glass . It's the ordinary glass we can see all around us. 

6. Glass Shaping 1. Floating Process : Molten liquid of glass poured on top of a big vat(A large tank or tub used to hold liquid, especially in industry.) of molten tin metal to make perfectly flat sheets of glass for windows.

7. Glass Shaping 2. Blowing Process : A "gob" (lump) of molten glass is wrapped around an open pipe, which is slowly rotated. Air is blown through the pipe's open end, causing the glass to blow up like a balloon. With skillful blowing and turning, all kinds of amazing shapes can be made.

8. Glass Shaping 3. Pressing Process : Molten gobs of glass are delivered into the mold and a plunger is used to press the glass into the shape.

9. Heat Treatment Annealing : Glass products usually have undesirable internal stresses after forming, which reduce their strength. Annealing is done to relieve these stresses. Annealing involves heating the glass to an elevated temperature and holding it for a certain period to eliminate stresses and temperature gradients, then slowly cooling the glass to suppress stress formation, followed by more rapid cooling to room temperature. Annealing temperatures are around 500 C.

10. Glass Types For green-tinted glass we use iron and chromium based chemicals to the molten sand. Bullet proof glass is made from laminate of multiple layer of glasses and plastic bonded together. For a fine crystal glass that can be cut more easily, we use lead oxide in it. Toughened glass use in car windshield is made by cooling molten glass very quickly to make it much harder. Green-tinted Bullet proof Crystal Glass Windshield

11. Advantages Preferred for food and beverages Important role in transportation Key element in architecture & buildings Part of renewable energy strategy Crucial in modern communications Many pharmaceutical, health and science applications

12. Disadvantages Manufacturing of glass is high energy consuming process due to high temperature required for processing the raw material. The glass is very rigid and brittle material so when it is subjected to stress it breaks without significant (strain). Use of glass also enhance the cost of security. The glass is also unsafe for earthquake proven area. And many more.