In 1977, Otto Hofstetter AG produced its first injection mould for PET preforms. The customer was the Continental Can Company, which had been commissioned by two well-known American beverage brands to find a capable tool manufacturer. The resulting design was twelve PET moulds with 16 cavities producing preforms for two-liter bottles. The preforms had a wall thickness of four millimetres, weighed 62 grams and were produced with a cycle time of 30 seconds.
Know-how accumulated over decades.
More than four decades later, PET bottles are used around the world and produced in countless variations. Almost one in every seven PET containers produced to date has been made with a preform from Otto Hofstetter AG. And the pioneer toolmaker for PET preforms, Otto Hofstetter AG, has continued to develop and innovate.
The experts at Otto Hofstetter AG have continuously expanded their knowledge of tool design. Our extensive knowledge about the entire PET production process, the materials in demand on the market and the complete product cycle for PET containers all combine to deliver enhanced profits to our clients, the world’s PET producers and fillers.
Our knowledge adds value.
Otto Hofstetter AG makes its extensive knowledge base and its decades of experience available to its customers. It offers a range of services for the production of PET preforms, which, according to the needs of the project partners, can start with the design of the container and extend to monitoring the quality of the preforms coming off the production line. Customers can choose which process steps should benefit from the know-how of the specialists from Switzerland. Experience gained from thousands of projects shows that the earlier we get involved in a project, the greater the possibilities we have to make the process leaner and more efficient, which can decisively influence the weight and quality of the preform, thereby saving valuable time and money.
Safety right from the start.
Otto Hofstetter AG’s full range of services for the production of PET preforms begins with clarifying the customer’s needs. Our experienced engineers can then best support the project with their technical know-how. They can draft detailed preform proposals and optimise them if the customer or the blow moulding machine supplier bring in ideas for refinement. As a further service, Otto Hofstetter AG builds sample moulds and produces test preforms, with the final production conditions simulated as precisely as possible. These test preforms are delivered to the customer for further fine-tuning, be it to determine blowing behaviour, filling or even for consumer tests. If the preform and the blow mould fit perfectly, the way is clear for the construction of the series mould. Preforms are produced on each finished series tool, the quality of which is thoroughly checked. Together with the results of the tests, the optimised injection mould is then delivered to the customer.
Added value at every step.
Otto Hofstetter AG takes customer support very seriously, offering a comprehensive range of services. Here, our advantages are clear: Our total process know-how helps us optimise every step of the preform production line, reducing construction time and saving costly resources.
1)
Our advice can add value at every stage of a project. We have often seen that, depending on the requirements, it may make sense to involve our Swiss specialists when a prototype of the planned PET bottle has been developed. This enables important benchmarks to be set for the future quality of the preforms and the bottle. Information about the desired neck shape, the target weight and, if possible, the bottle design are absolutely essential to the optimal design of the preform.
2)
Technical optimisation demands two distinct skills. On the one hand, our engineers develop a proposal for the required preform based on the targets defined in the preliminary discussions. Then, based on the performance data of the machine on which the preform will be produced, the experts on the Otto Hofstetter AG team calculate the cycle time to be achieved. Preform design and cycle time calculations are transmitted to the customer.
3)
If a preform already exists that a manufacturer wants to produce in the future with a mould from Otto Hofstetter AG, our know-how can also provide value-adding ideas. The preforms and the associated specifications are checked in detail by our toolmakers for possible optimization. It is not uncommon at this stage to find opportunities to improve the quality or efficiency of the preform. For example, for a well-known German distributor, small corrections to the geometry of the preform resulted in a weight reduction of 1.55 grams, which, over the course of a year, meant a savings of around 5000 tons of plastic.
4)
The provisional preform goes to the blow mould ma-chine manufacturer for testing. In this important project step, it can be wise to involve the developer of the preform directly. In this way, no important information is lost and queries
can be clarified directly between the experts.
5)
The final drawings of the preform are produced by Otto Hofstetter AG’s engineers after receiving feedback from the blow moulding machine manufacturer. Every angle, rounding, cone and taper is calculated and defined to the nearest hundredth of a millimetre.
6)
In the next step, in order to sample the preform, the mould inserts are manufactured and built into a standard, pre-existing mould. Depending on the number of samples required, a sampling mould consists of two to 16 cavities. These tests are mostly carried out in the Otto Hofstetter AG Service Centre in Switzerland. The same granulate later used in series production is used and the factory conditions are simulated as closely as possible. Depending on the further course of the tests, the samples’ production run can be a small series or several thousand pieces.
7)
Manufacturing the production mould commences when all tests have been carried out successfully and all target values for quality and performance have been achieved. The production of the tool follows a clearly structured and proven process. This ensures that the project is completed efficiently and within the agreed time frame. The result is a preform mould that has the well-known quality of an Otto Hofstetter AG solution.
8)
After completion, every new injection mould is put through its paces. This can be in the test centre at our headquarters in Uznach or at a cooperating machine manufacturer. The preforms produced during the tests are also carefully checked.
9)
The quality assurance of the preforms involves a three-step process. The geometric dimensions are checked using a high-precision optical measuring device. The preforms are also visually assessed. Every little abnormality or flaw is identified and reported by experienced inspectors. The collected test results are examined. If all quality parameters meet the requirements, the results of the inspection go to the customer together with the finalised mould. These services are available to customers during the entire production period of a preform.
This is how we make sure our customers get the best, most efficient PET mould possible. At Otto Hofstetter AG only one standard applies: complete customer
satisfaction.
