PET technology favours wider ranges, shorter runs

Developments in polyethylene terephthalate (PET) injection blow moulding technology are now benefitting UK manufacturers, with options of wider container ranges (and wider necks), as well as economical shorter runs.

Amcor PET Packaging has installed the latest single-stage moulding at its Gresford factory, and is currently installing a second machine. According to business development manager Mike Hanratty, the first of these will be devoted to Glaxo Smithkline products, including oral care, while negotiations are still under way for capacity on the second machine.

Crucially, while Gresford's existing machines are high-volume two-stage systems, used especially for beverage applications, the new machines will be suitable for wider-mouth containers such as jars. Here, pack sizes can vary between just 50ml and five litres, says Hanratty.

While avoiding specifics, Amcor says the technology is an 'intermediate' design between traditional single-stage and high-output two-stage production. Says Hanratty: "The aim is to diversify beyond beverages. We could also use this as a stepping stone for lower volumes, allowing customers a lower entry cost."

Gresford is by no means the first operation to combine single-stage with two-stage manufacture. Constar in the US says it uses both. A spokesman explains: "The one-step equipment generally runs wide-mouth containers such as peanut butter jars. Here, the wide-mouth opening disadvantages the two-step process and the best economies are realised in one-step."

But Constar notes one drawback of the type of single-stage machines it uses: relatively long changeover times, necessitating careful production planning.

Amcor's Gresford plant produces around 3bn preforms a year, of which one-third are blown in-house.