Pursuing Quality and Performance

“There is nothing more satisfying than taking a bottle design and seeing it go into full manufacture, our dedicated production teams being responsible for every aspect of the manufacturing process, their focus being on making sure each and every bottle is the very best it can be.”

Richard Summers, Operations Director

How Glass Packaging is Made

The mixture

Glass for packaging is made from abundant natural raw materials:

  • Silica (sand)
  • Sodium in the form of Sodium Carbonate (soda ash)
  • Calcium in the form of limestone
  • Other ingredients, including colorants.

Cullet is also added to this mixture. Cullet is broken glass, at Allied we use scrap from the manufacturing process, or from recycling centres which are resourced by bottle banks or kerbside collection systems. The use of cullet is beneficial because it enables discarded packing to be utilised whilst also saving energy and raw materials.

Melting

The mixture of raw materials and cullet is melted in the furnace, where they are heated to a temperature of around 3,180° F. It takes around 24 hours from the raw materials entering the furnace for them to be converted into glass. At Allied, the furnaces operate 24 hours a day, seven days a week and have a lifespan of about ten years.

The molten glass is carried through a series of distribution channels these are known as forehearths – to the forming machines. At the end of the forehearths, the glass flow is cut into gobs whose weight, shape and temperature are precisely controlled.

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Forming

The forming process transforms the compact mass of the glass gobs into a hollow shape:

  • The gob is transformed by pressing or blowing into an intermediate hollow pocket shape, with the opening fully formed.
  • A mechanical arm then transfers this partially formed shape over to a finishing mould for blowing into the final shape of the bottle or jar. The finished glass object is then taken out of the finish mould by tongs and held briefly over a cooling plate, before being conveyed away.

The whole forming cycle only takes a few seconds.

Cooling

To make the containers more resistant to scratches, they are treated with two surface coatings, one applied when they are still hot and again when they are cooled.

To ensure the solidity and stability of the formed glass containers, they then need to be cooled in a controlled way. This takes place within an ‘annealing lehr’, the process taking between 30 minutes and two hours.

Inspection

Then every container made at Allied undergoes rigorous quality checks with a range of equipment, inspecting the neck area, dimensions, glass thickness and appearance.

Any container which is unacceptable is automatically rejected and returned to the furnace to be re-melted.