Container Glass Manufacture by Automatic Process
Until the second half of the 19th century bottles were made by hand gathering, blowing and finishing the neck. A semi automatic method of bottle making was developed after 1850 but this has since been replaced by the fully automatic process. All bottles and jars are now made automatically by one of two methods - Press and Blow or Blow and Blow.
The Blow and Blow method
Molten ‘gobs’ of glass are delivered into a mould known as a ‘blank’ or parison mould. A puff of compressed air blows the glass down into the base of the mould to form the neck or ‘finish’ part of the bottle or jar. A second blast of compressed air is then applied through the already formed neck of the container to form the ‘parison’ of pre-form for the bottle against the walls of the parison mould cavity. The thick walled parison is then transferred to the final mould during which time the surface of the glass ‘reheats’ and softens again enough to allow the final container shape to be fully formed against the walls of the final mould cavity by the application of either compressed air or vacuum. The container is then removed and transferred to an annealing oven (lehr) where it is reheated to remove the stresses produced during forming and then cooled under carefully controlled conditions.
The Press and Blow method
Molten ‘gobs’ of glass are delivered into the parison mould and a plunge is used to press the glass into the parison shape. The final mould stage of the process is the same as that described for the Blow and Blow Process. Making Glass Containers by Automatic Process
The Press and Blow Process
The Blow and Blow Process
Independent Section, or Individual Section, (I.S.) Machines
The I.S. machine process has now universally replaced almost all others. It is not certain whether ‘IS’ denotes its inventors, Ingle and Smith, or its main characteristic which is independent synchronised units with a synchronised gob distribution system to each section (i.e. Individual Section). I.S. machines can comprise of several sections and 10 & 12 section or even 16 to 20+ section tandem machines are now common.
These machines can operate on the blow and blow or press and blow principle and double, triple or even quad gob production, i.e. delivery of two/three/four gobs of glass at the same time is common. A typical modern machine configuration is capable of producing more than 600 containers every minute.
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The energy saving from recycling a single bottle will power a 100-watt light bulb for almost an hour or a colour TV for 20 minutes.