ACCRUTEK

Polymer Engineering Consultancy

Innovation Design Development

Blow moulding enables the production of bottles, containers and technical components in a wide variety of styles.

 

One of the most common techniques is extrusion blow moulding where a tube or “parison” is extruded vertically to the required length and two mould halves close around it forming a pressure weld around the top and bottom. Compressed air is used to inflate the parison to the form of the mould.

Many innovative shapes have been developed over the years which are now commonplace on store shelves.

 

The other significant technique is injection blow moulding where a preform is injection moulded, providing a precise neck form and test tube shaped body. This is subsequently re-heated to allow blowing in a second mould. As the tube expands to the form of the mould it is bi-axially stretched which significantly increases the strength and optical clarity of the bottle. This very thin pressure vessel has become an essential component in the supply of carbonated drinks and water throughout the world.

 

The packaging industry has also benefited from multi layer extrusion which uses a series of extruders to create a co-axial extrudate. This can be used for the production of bottles and containers but also for film.

 

Technical blow moulding has played a significant role in the automotive industry in the form of multi layer fuel tanks and tubular conduit structures for fluid or air ducting. A large number of components in a sub assembly can sometimes be replaced by one blow moulding. Alternative processes which can be considered are gas or water assisted injection moulding – see injection moulding.

 

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