In 1977, Otto Hofstetter AG built the first injection mould for the production of PET preforms. The client was the Continental Can Company, which had the mandate to produce new drinks packaging for Coca-Cola and Pepsi. The order consisted of 12 injection moulds with 16 cavities, many of which were designed to produce preforms for 2-litre bottles.
Quality in all dimensions.
In the meantime, well-known PET producers in Asia, North and South America, Australia, Africa and Europe count on the performance of the Swiss-made tools. To achieve mould availability of more than 95 percent starts with only using high-quality components and having them assembled and checked with great care by highly experienced toolmakers. In addition to uncompromising craftsmanship, to achieve the much-praised performance of the moulds from Uznach requires more. For example, innovative refinements like the OH Xtreme® coating, which enabled a 72-cavity mould to make more than 15 million cycles before its first maintenance. Or OH Xtra® surface treatment, which has reduced average roughness (RA) from 0.2 to 0.3 microns conventionally to only 0.05 to 0.1 microns.
Convincing performance for customers.
As their testimonials confirm, many well-known PET preform manufacturers that Otto Hofstetter AG’s Cavity-Lock mould design has a much longer service life than conventional feed-in designs, and revisions have been needed after 10 million cycles at the earliest. According to the latest reports from producers, this target can even be exceeded. Other feedback praises the compatibility of the moulds, which significantly increases flexibility when producing lower volumes. For example, in Austria, a 48-cavity preform mould for 1.5-litre bottles has been running without a rebuild for 22 years, and, in Indonesia, a 96-cavity mould for 0.6-litre bottles has been in continuous service since 2007. The hot runners are also marathon performers. In Belgium, one of our hot runners has been in daily use since 2014, clocking almost 16 million cycles and counting.
A new chapter.
Recently, Netstal, our long-standing Swiss machine-building partner, has developed the new PET-Line series with integrated lateral robotic removal and post-cooling. In order to continue this Swiss success story, the management of Otto Hofstetter AG decided to build the appropriate side-entry moulds for PET-Line injection units. Thus, our customers can now choose between top- and side-entry layouts, both from Otto Hofstetter AG.
Small twist, same performance.
The move from our proven top-entry to side-entry moulds basically just required a rotation of 90 degrees. For this purpose, some small technical adjustments had to be made in the design. This means that the side-entry moulds include all the quality and features of our top-entry injection moulds. The stack structure is also executed with Cavity-Lock, and the new performance-enhancing options such as OH XCool® and OH Xblow® can also be integrated into the mould. In addition, all end-of-arm-tools (EOATs) are available to match the selected preform. The hot runners are developed and manufactured at Otto Hofstetter AG in Switzerland and comply with all relevant standards.
Impressive test results.
At the beginning of March, a side-entry tool from the Uznach toolmakers was installed in a new PET-Line 4000 for testing purposes at Netstal. The 96-cavity mould was designed for a preform with a 38-millimetre 2-start thread, a weight of 50 grams and a wall thickness of four millimetres. The EOAT cooling ran over four positions, the air cooling over three. After a short break-in run for the mould and some small optimisations, peak values were quickly achieved. With a cycle time of 13.9 seconds and an injection speed of 22.5 grams per second and cavity, Otto Hofstetter AG’s new side-entry mould already exceeded expectations in its first tests.
