Otto Hofstetter AG started making moulds for PET preforms in 1977. The first order was placed by the Continental Can Company which had been commissioned by two major American beverage producers to evaluate a capable mould maker. Moulds for PET preforms are now a very important part of the business in Uznach. The technical specifications for preforms and production equipment have changed substantially.

We write the year 1977. Sylvester Stallone is awarded the Oscar for his performance in “Rocky”. A young British band by the name of “Dire Straits” comes for the first time on BBC and Muhammad Ali wins by points against Earnie Shavers in the Madison Square Garden. Not earning quite as much publicity, representatives of the Continental Can Company visit a mould maker in Uznach, Switzerland. The American company is subcontractor to Coke and Pepsi and has received an order to develop a new type of packaging for beverages. For this purpose they have to find a mould maker who is able to design and produce a mould for preforms of the desired quality. Mould makers of the USA and Western Europe have joined the race. And although the owner of the Swiss company doesn’t speak a word of English, the Continental Can Company decides in favour of Otto Hofstetter AG.

First generation of preforms.
So much for the story. The order was for twelve moulds with 16 cavities each, to be built exclusively for the USA. The moulds ran on injection-moulding machines of the German manufacturer “Windsor” and met all specifications of the Continental Can Company as well as Pepsi and Coke right from the start. The majority of the moulds were laid out for the production of preforms for 2-litre bottles. The preform’s wall thickness was four millimetres and its weight 62 grams. The “Windsor” managed two cycles per minute.

Upright progress.
The original bottles had a round base and needed a separately moulded “base cup” to be able to stand upright. It was only natural that Otto Hofstetter AG also built the mould for the base cups. Thanks to the invention of the petaloid base by the Continental Can Company the base cup became obsolete some years later.

New performance with preforms.
38 years have passed since then. Preforms for 2-litre bottles are now made in 96-cavity moulds, they weigh 45.5 grams each and feature a wall section of 3.6 millimetres. The cycle time is normally at 13 seconds.




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