Glass Manufacturing Process Essay

Glass Manufacturing Processes

Glass Production involves two main methods:
• Float glass process
• Glassblowing

Float Glass Process
Float glass process is used to produce glass sheets of uniform thickness and a high degree of flatness precision. It is also known as the Pilkington process, as it was invented by Sir Alastair Pilkington in 1952. The process was initially used to make glass of only the standard 6 mm thickness, however with the expansion in science and technology, glass sheets with thicknesses ranging from 0.4 mm to 25 mm can be manufactured using this process.

Raw materials
Basic composition of float glass includes silica sand, soda ash (sodium carbonate), dolomite, limestone, saltcake (sodium sulfate) etc. Soda ash is added to facilitate easy melting, limestone increases the durability of the product and dolomite is added to improve the working and weathering properties. Other materials may be used as colorants or refining agents. The percentage composition of the raw materials has been shown in the table below.

Material Percentage Composition
Sand 72.6
Soda ash 13.0
Limestone

Raw materials enter through one end and plates of cut glass leave through the other. The six stages of production are as follows:

• Stage 1: Melting and Refining
Finely grained constituents, in a controlled ratio, are mixed into a batch which is then made to flow as a thin layer over molten glass inside a furnace maintain at 1500°C. Typically flat glass furnaces are 9m wide and 45m long and can accommodate between 1200 and 2000 tons of glass. Several processes like melting, refining, homogenizing of the constituents occur at separate zones in the furnace. This process is carried on for 50 hours until glass stabilized at 1100°C and is free from inclusions and bubbles. This entire process is the key to high glass quality.

• Stage 2: Float